ENERGY TRANSFORMATIONS DURING
HORIZONTAL WALKING
BY
FRANCIS G. BENEDICT
AND
HANS MURSCHHAUSER
WASHINGTON, D. C.
PUBLISHED BY THE CARNEGIE INSTITUTION OF WASHINGTON
1915
CARNEGIE INSTITUTION OF WASHINGTON
PUBLICATION No. 231
\
PRESS OF GIBSON BROTHERS, INC.
WASHINGTON, D. C.
CONTENTS.
Page
Introduction 5
Methods of determining the energy transformations during walking 7
Methods of studying the gaseous exchange during walking 8
Fundamental principle of studying the gaseous exchange incidental to walking . . 9
Units of measurement used in walking experiments 10
Previous researches on the gaseous exchange during walking 12
Summary of results of previous observations 21
Methods and apparatus for studies of muscular work 29
Description of apparatus used in this research 31
Universal respiration apparatus 31
Treadmill 34
Accessory apparatus 36
Method of recording the respiration-rate 37
Method of recording the pulse-rate 37
Step counter 38
Method of measuring height to which the body is raised 39
Plan of research 42
General routine of the experiments 44
Standing experiments 44
Sitting experiments 45
Walking and running experiments 46
Experiments with food 46
Subjects 47
Statistics of experiments 48
Discussion of results 61
Basal values 61
Basal metabolism of subject 1 62
Influence of food and body position 65
Basal metabolism of subject II 66
Metabolism in the lying position 66
Metabolism in the sitting position 67
Comparison of the metabolism in the lying and sitting positions 69
Metabolism in various standing positions 70
Influence of food upon metabolism in the standing position 72
Metabolism during walking 76
Walking experiments with subject 1 76
Experiments without food 77
Experiments with food 80
Energy required for the elevation of the body 80
Walking experiments with subject II 81
Experiments without food 82
Experiments with food 87
Influence of the character of diet on the heat-output per unit of work 93
Influence of fatigue upon the heat-output per unit of work 94
Comparison of the heat-output per unit of work during running with
that obtained during walking 96
Analysis of the mechanics of locomotion 98
ILLUSTRATIONS.
Fig. 1. General view of apparatus used for walking experiments 32
2. Schematic outline of universal respiration apparatus 34
3. Treadmill designed by E. H. Metcalf 35
4. Detail of ball bearing for steel tubes on the treadmill 38
5. Step counter 38
6. Apparatus for recording the height to which the body is lifted, and step
counter with connections 40
7. Typical kymograph record showing character of step 41
3
ENERGY TRANSFORMATIONS DURING HORIZONTAL
WALKING.
INTRODUCTION.
This investigation was undertaken after several long conferences
with Professor Zuntz of Berlin and Professor Durig of Vienna, whose
researches on the work of forward progression are classical. The pre-
liminary experiments were made during the sojourn at the Nutrition
Laboratory of Dr. Carl Tigerstedt of Helsingfors. Subsequently data
were acquired by Messrs. H. L. Higgins and L. E. Emmes of the
Laboratory staff. We wish to express our thanks to these gentlemen
and particularly to Dr. Tigerstedt for the data regarding Subject I.
A certain amount of walking on a level inevitably forms a part of
the daily routine of nearly every living person, for even those who are
designated as sedentary in then- habits do a not inconsiderable amount
of walking in the house or in short distances upon the street. To
one who has not computed the actual distance traversed by the
housewife during a day, the sum total of the distance walked is
surprising. Such a control may readily be obtained with a simple
pedometer, for although a pedometer can not be classified as an
instrument of precision and is subject to many errors that are fre-
quently overlooked, nevertheless it shows in a striking manner that
very few individuals close a day of ordinary life without having moved
in forward progression a distance of not less than 2 or 3 kilometers.
Not infrequently this distance is doubled or trebled by those who
would ordinarily assume that they had not taken a particularly long
walk. The personal experience of one of us while writing a report
showed that the walking for a day consisted in going twice to and from
the house, which was 400 meters from the laboratory, i. e., a total
distance of 1,600 meters, and in walking about the laboratory while
engaged in instruction and research. Throughout a period of several
months the pedometer, which was carefully controlled and tested,
showed that the average distance walked per day amounted to 7 miles
(11.27 kilometers).1 Undoubtedly innumerable instances even more
striking than this may be cited, which would show that it is reasonable
to assume that practically all persons do considerable walking during
the course of 24 hours. Inasmuch as there are many individuals whose
habit of life or profession requires a large amount of walking — for
example, those walking to and from business, mail carriers, and espe-
iBenedict, Proc. Am. Phil. Soc., 1910, 49, p. 162.
6 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
cially soldiers — an intimate knowledge of the physiology of walking is
obviously of great importance.
Practically all of the previous researches on the physiology of walking
have been conducted either from a desire to study the conditions inci-
dental to walking done in mountain climbing, the results being of
importance to physicians and those taking regular exercise, or, as in the
case of the classical researches of Zuntz and Schumburg, from a desire
to study the influence of walking on the metabolism, with a view to
applying the results directly to army movements. In the present day,
when special attention is directed towards efficiency, the minimizing
of extraneous muscular movements, and the transportation of material
by hand and leg motion with the least possible expenditure of physical
energy, we may assume that there is every incentive for studying care-
fully the physiology incidental to walking in a horizontal direction.
While from the abstract physiological standpoint a study of all of
the various factors incidental to walking is of great value, perhaps the
most important phase of the investigation is the study of the energy
transformations and the determination of the amount of nutrients in
the food necessary to provide for such activity. The results of such
study are of especial practical value in determining the energy require-
ments of an army engaged in marching a certain distance over a level
country. As previously stated, this thought dominated the study
of Zuntz and Schumburg. A more universal application of the results
may be made by the physician who, if he knows the energy involved in
walking, is able to prescribe more intelligently a definite amount of
exercise for the ambulatory patient. Furthermore, as physical exercise,
particularly walking, is an important factor in weight reduction and
in athletic training, exact information as to the energy required may
be put to practical use in such connection.
Theoretically the movement of 1 kilogram 1 meter would call for no
positive work other than that in overcoming the resistance of the air;
nevertheless a considerable amount of work is required of the human
body as a machine in accomplishing this feat of moving the mass in a
horizontal direction. The apportionment of the total energy output
of the body between that required for the maintenance of the vital
functions and that required for walking is not, however, simple. When
a person is walking, not only is energy required for the external mus-
cular exercise, but a heat production is necessary for the entire main-
tenance of the body activities, including muscular tonus, the work of
circulation, respiratory muscles, and the external work of balancing the
body in an upright position, none of these activities contributing
directly to the work required to move the body in a horizontal direction.
With only a knowledge of the amount of food eaten, it is impossible to
estimate the proportion of food required for the activity of walking and
that for vital maintenance. A closer analysis is therefore essential.
INTRODUCTION.
METHODS OF DETERMINING THE ENERGY TRANSFORMATIONS
DURING WALKING.
It is necessary, first of all, to study the energj^ transformations which
are peculiarly incidental to walking. Thus, in the simplest case, if
the person could walk directly in a vertical direction, a definite amount
of external muscular work would be performed which would be repre-
sented by the product of the weight of the body and the height walked.
In walking in a horizontal direction, theoretically no external work is
performed and there is no change in the potential energy of the body.
We are thus unable to measure the energy output by the kilogram-
meter, the unit most commonly used, or by any of the other ordinary
work units. Consequently we have very little information regarding
the energy output.
It is true that we must not disregard the extremely illuminating
researches of earlier workers, who have attempted to establish a con-
stant, although with wide variations, which would show approximately
the amount of energy required to move 1 kilogram 1 meter in a hori-
zontal direction. These researches will be referred to in a subsequent
section. It is important for us to note, however, that aside from such
methods of calculation as are based upon the constant established by
the earlier physiologists, we have no means of calculating the energy
output required in walking.
A possible method of measurement would be to determine the energy
output directly by having the subject walk inside of a calorimeter.
This has been attempted, although in an imperfect manner, by certain
French investigators, including Him1 and Chauveau,2 who used the
so-called " emission calorimeter" with a tread wheel. In these studies,
however, a large proportion of the work was done in lifting the body,
and hence the amount of forward progression, which is of special interest
to us, is complicated by the very much greater work involved in the
elevation of the body.
Finally, it is possible, owing to the valuable computations and
methods of research established by Zuntz, to study the respiratory
exchange, namely, the carbon-dioxide output and the oxygen intake,
and thus compute indirectly the total calorific output. This last
method has been adopted by all physiologists as the most suitable for
the purpose. Practically all previous research has therefore been
based upon the general principle of determining the total respiratory
exchange both while the subject is walking and during rest when lying,
sitting, or standing, and noting the increment in the carbon-dioxide
output and oxygen intake due to walking.
From the heat of combustion and analysis of pure nutrients, such
as carbohydrate and fat, it has been computed that for each liter of
, Recherches sur 1'equivalent mecanique de la chaleur, Paris, 1858.
2Chaveau, Compt. rend., 1899, 129, p. 249.
8 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
oxygen required in the combustion, there are produced from 4.686 to
5.047 calories. When pure carbohydrate is burned, each liter of oxygen
utilized in the combustion corresponds to 5.047 calories, but when pure
fat is burned each liter of oxygen corresponds to 4.686 calories. Zuntz
and his co-workers have prepared a table showing the calorific equivalent
of the oxygen consumption when fat and carbohydrate are burned.1 This
has been most ingeniously elaborated by Williams, Riche, and Lusk.2
By studying the output of carbon dioxide and the intake of oxygen,
not only is information secured regarding the total oxidation of material,
but also some idea is gained of the character of the combustion by
noting the relationship between the volume of carbon dioxide given off
and the oxygen absorbed. With equal volumes of carbon dioxide and
oxygen, this relationship or ''respiratory quotient" is 1.0 and indicates
that carbohydrate has been exclusively burned. When the respiratory
quotient approximates 0.7 the indication is that fat has exclusively
been burned. By this means, therefore, it is possible to compute with
great accuracy the heat output from the total oxygen consumption and
the respiratory quotient.
In certain earlier researches, and especially prior to the time when
methods were devised by which oxygen absorption could be more
easily determined than formerly, the measurements of the carbon-
dioxide output alone were used, but a much greater error is introduced
into the computations by this method. Unfortunately, of the two
factors, carbon dioxide and oxygen, that which is of the greater sig-
nificance, namely, oxygen, is the more difficult of determination, while
the measurement of the carbon-dioxide excretion is relatively a simple
matter.
METHODS OF STUDYING THE GASEOUS EXCHANGE DURING
WALKING.
Inasmuch as a study of the problem of the energy transformations
during walking demands a careful study of the gaseous exchange, we
find all the methods used based upon this principle. The simplest is
that in which the subject walks inside a closed chamber by means of
which the product of respiration — carbon dioxide — is easily collected.
This method was first employed by Sonden and Tigerstedt3 in the clas-
sical research with their large respiration chamber in the Karolinska
Institute in Stockholm. This chamber had a capacity of 100 cubic
meters and, unlike any respiration chamber previously used, permitted
the subject free movement. When the subject walked back and forth
across the room, a considerable distance could be traversed. At that
time only the carbon-dioxide output was determined with this method.
xZuntz and Schumburg, Physiologic des Marsches, Berlin, 1901, p. 361.
2Williams, Riche, and Lusk, Journ. Biol. Chem., 1912, 12, p. 357.
3Sonden and Tigerstedt, Skand. Archiv f. Physiol., 1895, 6, p. 165.
INTRODUCTION. 9
A second method involves the attachment of certain breathing appli-
ances, either nosepieces or mouthpiece, with an apparatus for meas-
uring the volume of the expired air. When the breathing appliances
have been adjusted, the subject assumes a certain body position and
then walks along a movable path, such as a treadmill. This method
was frequently used by Zuntz and Durig and their co-workers.
A modification of this method is that in which the apparatus for
measuring and sampling the expired air is carried upon the back of the
subject, somewhat as a knapsack would be carried. The subject is
then no longer confined to walking upon a treadmill, but may walk
on level ground anywhere. This method was used extensively by
Zuntz and Durig and their associates and by Douglas. Instead of
having the apparatus carried by the subject, it may be transported
by an assistant walking a suitable distance behind him. The subject
thus breathes through the nose or mouth appliance, but is not obliged
to support the heavy apparatus. This method was employed by Burgi,
Schnyder, and, in certain experiments, by Kolmer and Brezina.
Finally, it is possible to have the gas measuring and sampling appa-
ratus in a fixed position and the subject attached to it by a long tube.
He then walks in a clearly defined path, either back and forth across the
room or in a circle of which the apparatus is the center. This method,
which obviously limits appreciably the distance to be covered and the
general freedom of the subject, has found slight use with certain French
observers, particularly Amar.
FUNDAMENTAL PRINCIPLE OF STUDYING THE GASEOUS EXCHANGE
INCIDENTAL TO WALKING.
The method of superimposition is the only one feasible for these
studies. By this method the gaseous exchange during walking in dif-
ferent positions must be carefully studied by one or more of the methods
previously referred to; subsequently, in order to apportion specifically
the energy transformation due to walking, it is necessary that a certain
part due to the metabolism of maintenance be subtracted from the
result obtained for the total gaseous exchange.
The exact selection of the amount of energy transformed for main-
tenance to be deducted from the total energy transformation has been
a matter of considerable discussion. We have now come to realize that
a human individual may subsist on numerous metabolic levels. The
subject sound asleep, without food in the stomach, has a minimum
metabolism, but is utterly incapable of intellectual or physical activity.
It would obviously be impracticable, if not indeed undesirable, to
deduct this minimum metabolism from the measurement of the total
metabolism and assume that the difference would be wholly due to
the energy transformation due to walking. Even when the subject
is lying awake, we still have a base-line which is far removed from the
10 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
process of walking. To obtain the best expression of the superimposed
energy requirement for forward progression, it is necessary to secure, as
nearly as possible, the energy requirement of the subject in a position
which involves all of the extraneous muscular movements incidental to
the waking condition and in a vertical position. This may be obtained
by deducting the metabolism required for the standing position. And
yet the earlier researches have been most unsatisfactory in the attempts
to measure the metabolism under these conditions.
With the standing position we again have numerous possible varia-
tions. The subject may stand in a completely relaxed position; he
may possibly eliminate in a large part the effort of balancing by leaning
on a staff or lying back slightly out of the vertical against a support ; or he
may stand in a fixed position with rigid muscles, such as that of "atten-
tion." We should, theoretically at least, expect to find a considerable
difference in the metabolism necessary for these various upright positions.
Durig has clearly pointed out1 that there are numerous arguments
against assuming that the metabolism while standing in any one of
these positions can rightly be deducted from that during walking to
obtain the true energy transformation due to the walking, for it is quite
possible that certain of the external muscular movements incidental to
balancing and sustaining the body in an upright position may be greatly
modified, if not indeed dispensed with, in the ordinary motions of for-
ward progression. Consequently, one finds that, in previous researches,
the base-line used almost universally among physiologists has been the
metabolism observed with the subject lying awake without food in the
stomach, i. e., in the post-absorptive condition. The assumption is then
made that the increment of metabolism during walking over that observed
with the subject lying awake is a true measure of the metabolism due to
the muscular exercise of moving the body in a horizontal direction.
UNITS OF MEASUREMENT USED IN WALKING EXPERIMENTS.
While under ordinary conditions the amount of work performed in
any inanimate or animate motions is expressed in terms of foot-pounds,
kilogrammeters, or calories, it is obvious that no one of these units can
be appropriately employed for indicating the energy transformations
during walking. In walking, a given weight is carried through a given
distance. To be sure, there is inevitably a slight lifting of the total
weight of the body at each step due to the anatomical arrangement of
the feet and leg-muscles, but this wreight is again immediately lowered
to the same position, so that, mechanically at least, there is no effective
work accomplished. The only external evidence of performance is that
a given weight is moved forward a given distance.
In this discussion we may for the present appropriately eliminate the
possible effect of wind resistance produced by the body in walking or the
1Durig, Denkschriften d. math.-natur. Klasse d. kaiserl. Akad. d. Wissensch., 1909, 86, p. 267.
INTRODUCTION. 11
external influence of the wind in a direction either favorable or unfav-
orable for forward progression. But in practically all walking done
by man considerable differences exist in the weight moved forward . With
the bather walking on a flat sandy beach we have simply the weight of the
body plus the negligible weight of the bathing-suit. On the other hand,
with a pedestrian taking his " constitutional," we have the weight of the
clothing, amounting to 3 or 4 kilograms, possibly supplemented by the
weight of knapsack, camera, and other accessories. Finally we have the
exaggerated case of the fully equipped trooper carrying knapsack, emer-
gency rations, and a considerable quantity of ammunition. Thus we
have the possible necessity of distinguishing between the movement due
to the lifting of body-weight and that due to lifting inert or dead weight.
The subject is further complicated when we attempt to analyze the
weight of the living organism. The body is made up of bone, muscle,
and fat. Fat may be looked upon as inert body-material, and when
there is an excessive accumulation of fat, as with obese persons, it is
possible that it may be considered in great part as dead weight. It
is thus seen that the problem of studying the physiology of forward
progression involves the question of analyzing the character of the
weight transported. For the present the unit of accomplishment in
the work of forward progression on a horizontal plane must be con-
sidered as the transportation of 1 kilogram 1 meter, i. e., 1 " horizontal
kilogrammeter . "
12 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
PREVIOUS RESEARCHES ON THE GASEOUS EXCHANGE
DURING WALKING.
Before reporting and discussing the results of our own experiments, a
brief abstract is given of all previous research in which the metabolism
during walking has been studied. In thus reviewing the work of other
investigators, it has seemed advisable to record the results on the basis
of the movement of 1 kilogram over 1 meter of level path, i. e., 1 hori-
zontal kilogrammeter, and to compare them in a large summary table
rather than to give them under each research. This is done in table
1 (see pages 22 to 27).
Observations of Smith, 1859. — The earliest attempt to measure the
gaseous metabolism during walking was made by Edward Smith, who,
in his memoirs entitled "Experimental inquiries into the chemical and
other phenomena of respiration and their modifications by various
physical agencies,"1 gives the details of two walking experiments. In
these experiments Smith collected the products of respiration by attach-
ing a mask to the face and forcing the expired air through specially
constructed boxes, containing caustic potash to absorb the carbon
dioxide. The mask had two openings, one for inspired air and the
other for expired air, a valve system providing for the separation of the
two currents of air. A dry gas-meter was attached at the intake point.
The expired air was first passed through a Woulff bottle containing
pumice-stone and sulphuric acid, then into a gutta-percha box contain-
ing a solution of caustic potash, and finally through a second Woulff
bottle containing pumice-stone and sulphuric acid. The walking was
done inside of a room and covered a distance of approximately 10
meters in each direction. All of the precautions incidental to modern
experiments as to recording the barometric temperature and pressure
were taken, and a further factor, which is only too frequently neglected
in modern work, namely, pulse-rate, was also recorded. The subject
carried a spirometer which weighed 7 pounds, but the exact method of
transportation is not clear from Smith's description. Both experiments
were made in one afternoon, with an intermission of an hour. During
the first experiment he walked at the rate of 2 miles an hour and during
the second at the rate of 3 miles an hour. For a base-line he deter-
mined the metabolism at rest without food and in a sitting position.
Smith's values, which are given in English grains, were recomputed
to grams by Sonden and Tigerstedt.2 While walking at the rate of
2 miles an hour, the carbon dioxide per minute was 1.173 grams; at 3
miles an hour, 1.674 grams; and sitting at rest without food, 0.482
gram. The energy per horizontal kilogrammeter computed from these
values is given in table 1, page 22. The results obtained by Smith
have been criticized by Gruber3 and Voit,4 who both consider them
'Smith, Phil. Trans. Roy. Soc., London, 1859, 149, p. 681.
2Sonden and Tigerstedt, Skand. Archiv f. Physiol., 1895, 6, p. 166.
3Gruber, Zeitschr. f. Biol., 1891, 28, p. 470.
4Voit, Hermann's Haudbuch der Physiologic, 1881, 6, p. 201.
PREVIOUS RESEARCHES ON GASEOUS EXCHANGE.
13
somewhat high. Katzensteiri1 likewise considers the values too high
and inexact and regrets that Smith did not state whether the walking
was done on a level or on an incline. Although Smith gives the weight
of the subject and the apparatus in one instance, Katzenstein criticizes
the absence of body-weights for each experiment. Katzenstein's
further criticism, that the carrying of the apparatus by the subject was
a fault in the technique, is of special interest in view of the subsequent
use of a portable gas-meter by Zuntz and his co-workers.
Observations of Gruber, 1891. — The unusual interest in mountaineer-
ing, which is particularly active in Switzerland, has resulted in a large
number of physiological observations upon the effect of high altitudes
on the human body. One of the earliest of the observations, which
included measurements of the gaseous metabolism, was that of Gruber,2
who published the results of a research carried out in the Physiological
Institute at Berne under the direction of Professor Kronecker. Gruber
himself was the subject of the study.
Instead of using a mask with two valves, Gruber employed a tube in
the mouth for expiration, the nose being closed by the fingers of the
left hand. During inspiration the rubber tube leading to the mouth
was tightly closed by the teeth and air was inspired through the nose.
The inspired air was passed into a U-tube containing soda to absorb the
carbon dioxide. A rubber air-cushion, which could be compressed by
the arm of the subject, permitted the accumulation of the excess of air
during the expiration, and during inspiration this air was forced out
through the absorbing vessels by pressure with the arm.
Three experiments are reported in which the subject walked without
other load than the apparatus. The rate of walking in the first
experiment was 80 steps per minute. Two of the three experiments
consisted of 10 minutes of walking followed by 10 minutes of sitting,
Gruber concluding from his results that apparently as much carbon
dioxide is excreted in the 10-minute rest after the short walking-period
as during the walking. He also made three experiments while sitting
in a chair prior to walking and two experiments after walking. On the
basis of the sitting values he contends that with walking on a level
the carbon-dioxide production is twice as great as with sitting. Both
the rest and walking experiments were made 5 or 6 hours after food.
Comparing the results of observations made both in trained and
untrained condition and considering the amount of carbon dioxide
produced during rest as 1, he obtained the following figures:3
Rest.
Walking.
Ascent
(untrained) .
Ascent
(trained) .
Series 1 ...
1
'2.00
4.1
3.3
Series 2 ...
1
1.75
3.05
2.42
Incorrectly stated as 1.89 by Gruber and recalculated by us.
Katzenstein, Archiv f. d. ges. Physiol., 1891, 49, p. 331.
"Gruber, Zeitschr. f. Biol., 1891, 28, p. 466. 3Ibid., p. 490.
14 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
From these data he concludes that the carbon-dioxide production of
a working man is not a function of his work, since the metabolism
decreases with practice.
Observations of Katzenstein, 1891. — In the walking experiments of
Smith and Gruber, only the carbon-dioxide production was deter-
mined, and the first investigations, in which the oxygen consumption
was also measured, were those carried out by Katzenstein1 in Zuntz's
laboratory in Berlin. Employing the Zuntz mouthpiece and valves
for separating the inspired air from the expired air, Katzenstein
sampled and analyzed the expired air, the measurement of the total
amount of air expired being made with a gas-meter. There is consider-
able doubt as to the conditions of the experiments. In certain instances
it is specifically stated that the subjects were in the post-absorptive
state, i. 6., without food for 12 hours, but the general impression is given
that in the majority of instances the experiments were not made with
the subject in the post-absorptive condition. The rate of walking was
from 51 to 92 meters per minute. The criticism was subsequently
raised by Durig2 that the treadmill was not completely level, there
being a slight elevation of somewhat less than 1 degree. To provide
a base-line for these observations, the metabolism of the subject was
measured while he stood quietly upon the treadmill. Observations
were likewise obtained with the subject in a lying position. The author
concludes that the oxygen consumption for the unit of effective work is
greater for small amounts of work than for large amounts, and that the
respiratory quotient during work remains essentially unaltered. The
computation of the values per horizontal kilogrammeter is given in
table 1, page 22.
Observations of Sonden and Tiger stedt, 1895. — The large respiration
chamber in Stockholm afforded sufficient space for experiments in
which the work of walking could be measured.3 The carbon dioxide
alone was determined and with most of the experiments moderate
amounts of food were taken. The body-weight with clothing was
recorded before and after the experiment. The subjects walked
from 3,000 to 5,920 steps per hour without a load. As a base-line the
authors used a value found for three resting periods when the subject
was sitting, these periods being between periods of walking; large
differences are shown in the carbon-dioxide output per hour during the
resting periods. The energy per horizontal kilogrammeter, as com-
puted from the carbon-dioxide output during the walking experiments,
is given in table 1, page 22.
Observations of Schumburg and Zuntz, 1896. — In connection with a
series of experiments made in the Alps, Schumburg and Zuntz carried
Katzenstein, Archiv f. d. ges. Physiol., 1891, 49, p. 330.
2Durig, Denkschrift. d. math.-natur. Masse d. kaiserl. Akad. d. Wissensch., 1909, 85, p. 250.
3Sonden and Tigerstedt, Skand. Archiv f. Physiol., 1895, 8, p. 1.
PREVIOUS RESEARCHES ON GASEOUS EXCHANGE. 15
out a number of observations in Zuntz's laboratory in Berlin, using the
treadmill.1 A dry gas-meter weighing 7 kilograms was employed and
was carried by the subject. In most of the experiments the inspired
and expired air were separated by a valve system and a mouthpiece and
nose-clamp were used. It is interesting to note that in the severe work
of going uphill in this series of experiments, the authors record that the
breathing appliances were very uncomfortable, particularly the nose-
clip. They accordingly trained themselves to inspire through the nose
and expire through the mouth, a procedure which they satisfied them-
selves gave accurate results. To establish a base-line, numerous exper-
iments were made with the subject in a sitting position, these being
carried out in the laboratory in Berlin, in the hotel at Zermatt, and also
in the camp and on the glacier in the mountains. Three walking
experiments were made with Zuntz as subject in a room of the labora-
tory building and two on the treadmill, which was in a practically hori-
zontal position. Two treadmill experiments were also made with
Schumburg as a subject. The energy per horizontal kilogrammeter, as
computed from the difference between the sitting values and the walk-
ing values, is given in table 1, page 22.
Observations of A. Loewy, J. Loewy, and L. Zuntz, 1897. — In connec-
tion with their studies in the Alps, A. Loewy, J. Loewy, and L. Zuntz
made several experiments in Berlin on the treadmill in the Landwirt-
schaftliche Hochschule.2 Two experiments were made with A. Loewy,
three with J. Loewy, and five with L. Zuntz. A 6.6 kilogram dry gas-
meter was carried by the subject on his back and connected with the
Lob valve attached to the mouthpiece. The nose was closed with a
clamp. For the experiments made with A. Loewy, a base-line was used
which was founded upon earlier observations. The resting values for
J. Loewy and L. Zuntz were determined presumably with the subject
sitting. No statement is made as to whether the subjects were in a
post-absorptive condition or not. Certain experiments were also made
at Col d'Olen, in which the subject likewise carried the dry gas-meter,
but for these experiments the resting values were obtained with the
subject in a lying position. The results for the observations with the
subject walking on a level are summarized in table 1, page 22.
Observations of L. Zuntz, 1899. — In his observations regarding the
gaseous-exchange of bicycle-riders, Leo Zuntz included a number of
experiments made on the treadmill in the Landwirtschaftliche Hoch-
schule.3 The statement is made that the treadmill had an inclination
of approximately 1 degree. Of special interest in these observations
is the fact that Leo Zuntz paid particular attention to the influence of
speed upon the gaseous metabolism, varying the rate of walking from
JSchumburg and Zuntz, Archiv f. d. ges. Physiol., 1896, 63, p. 461.
2A. Loewy, J. Loewy, and L. Zuntz, Archiv f. d. ges. Physiol., 1897, 66, p. 477.
3L. Zuntz, Untersuchungen iiber den Gaswechsel und Energieumsatz des Rad ahresHirsch-
wald, Berlin, 1899.
16 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
53.45 meters per minute to 145.53 meters per minute. In the treadmill
experiments the stationary wet gas-meter was used and consequently
the subject was not obliged to carry an excessive load. The author
discusses the absence of wind-resistance and points out that at the
forced speeds, the treadmill ran so irregularly that it was frequently
necessary for him to run two or three steps. The research is especially
worthy of note as representing an attempt to secure unusual accuracy,
although one could wish that the experiments had been made with the
subject in the post-absorptive condition. An abstract of the results
obtained at the different speeds is recorded in table 1, page 22.
Observations of Setschenow and Schaternikow, 1900. — Setschenow and
Schaternikow1 report a research made at the physiological institute of
the University of Moscow, which included six walking experiments,
the length varying from 64 to 75 minutes. Three of these experiments
were preceded by a preliminary period of 6 to 9 minutes in which the
subject stood. Basal values were obtained in two additional experi-
ments with the subject at complete rest. In the walking periods the
subject, who was the fireman of the institution, walked back and forth
in the courtyard, the speed averaging 62.47 meters per minute; the
distance walked in each experiment was usually 4,455 meters. All of
the experiments were made 3 to 4 hours after a light breakfast of white
bread and tea. As the data given are unfortunately insufficient for
computing the values per horizontal kilogrammeter and do not lend
themselves to tabular presentation, this research is not included in
table I.2
Observations of Frentzel and Reach, 1901. — In studying the influence
of an unbalanced diet upon muscular work, Frentzel and Reach made a
number of observations with the subject walking on the Zuntz treadmill
in the level position in the Landwirtschaftliche Hochschule in Berlin.3
The rate of walking varied from 31.39 to 80.15 meters per minute.
The resting metabolism was determined with the subject lying upon a
couch, but both the resting and walking experiments were made with
food in the stomach. Resting experiments were made on 16 days with
subject F and on 12 days with subject R. A considerable number of
resting experiments were made prior to the walking period and on days
other than the walking days. Durig has criticized the experiments
as showing unusually large fluctuations in the energy required per hori-
zontal kilogrammeter. A summary of the results is given in table 1,
page 22.
Observations of Zuntz and Schumburg, 1901. — In their extensive
research on the physiology of walking, Zuntz and Schumburg made
'Setschenow and Schaternikow, Le Physiol. Russe, 1900, 2, p. 44.
2War conditions make it impracticable for me to communicate with my personal friend, Professor
Schaternikow, regarding the figures in this research. As they stand, if a body-weight is assumed
and a resting base-Jine deducted, values representing only about 50 per cent of those found in
other published researches are obtained. — F. G. B.
3Frentzel and Reach, Archiv f. d. ges. Physiol., 1901, 83, p. 477.
PREVIOUS RESEARCHES ON GASEOUS EXCHANGE. 17
numerous observations of the respiratory exchange of two students,
B and P.1 The experiments were made in Zuntz's laboratory and the
treadmill was used. In most of the experiments the subjects carried
the German army equipment with a considerable load, the maximum
weight of the load being 31.5 kilograms. In some of the experiments
they carried no load, and it is these latter experiments with which we
are chiefly concerned. The basal values were obtained with the sub-
ject lying upon a sofa. Both the resting and walking experiments
were made after the subject had taken a light breakfast. The usual
correction for the slight elevation of the treadmill is considered. The
experiments were so adjusted that both subjects could walk at the same
time upon the treadmill and two complete sets of respiration apparatus,
including gas-meters, were employed. The energy per horizontal
kilogrammeter is given in table 1, page 22.
Observations of Durig and Zuntz, 190 4.. — Observations on the metabo-
lism during walking on a horizontal level were carried out in Vienna, Col
d'Olen, and Capanna Margherita by Durig and Zuntz, and their results
were published in 1904.2 The dry gas-meter and the mouthpiece,
valves, and nose-clamp were employed. The resting experiments were
made every morning with the subject in bed, except when a study was
made of the after-effect of work. Some of the resting values used for
experiments with Zuntz as a subject were taken from the published
results of a previous research. Both the resting and walking experi-
ments were without food. After the basal values obtained with the
subject lying in bed had been deducted, the energy per horizontal kilo-
grammeter was computed and is given in table 1, page 22.
Observations of Caspari, 1905. — In his study of vegetarianism, Cas-
pari3 had an opportunity of studying the metabolism of two compet-
itors in a walking-match from Dresden to Berlin, one of whom was a
vegetarian and the other subsisted on a mixed diet. The experiments
were made upon a treadmill in Zuntz's laboratory and presumably the
Zuntz technique was carried out in all details. Striking differences
in the gait of the two subjects were noted. One of the subjects, K. M.,
won the match, proving himself a particularly efficient walker. The
basal values were obtained while the subject was lying in absolute rest.
The walking experiments were made with food, and probably the rest
experiments also, although no statement is given in regard to the food
with the rest experiments. After the basal values had been deducted
from the values found with the treadmill, the energy per horizontal
kilogrammeter was computed and is given in table 1, page 24.
Observations of Zuntz, Loewy, Mutter, and Caspari, 1906. — In con-
nection with the classical research on the physiology of man in high
xZuntz and Schumburg, Studien zu einer Physiologie des Marsches. Hirschwald, Berlin, 1901.
2Durig and Zuntz, Travaux de 1'annee 1903, Laboratoire scientifique international du Monte
Rosa, Turin, 1904, p. 65; also Archiv f. Anat. u. Physiol., Physiol. Abth., 1904, Suppbd., p. 417.
3Caspari, Archiv f. d. ges. Physiol., 1905, 109, p. 473.
18 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
altitudes, which was made in the Alps, Zuntz, Loewy, Miiller, and
Caspari1 carried out a series of resting and horizontal walking experi-
ments in Berlin. The resting experiments were all made with the sub-
ject lying in bed in the morning before taking food. The experiments
on horizontal walking were presumably without food and hence it is
permissible to deduct the basal values directly to compute the energy
per horizontal kilogrammeter. (See table 1, page 24.) The large wet
gas-meter was doubtless employed in the Berlin experiments, together
with the rest of the Zuntz technique. The walking experiments on the
treadmill were as follows: With Waldenburg, 9; with Kolmer, 4; with
Caspari, 5; with Miiller, 6. The especially high values found with
Kolmer in this research are commented upon at length by Durig.2
Observations of Durig, 1906. — In connection with an expedition in the
Alps, Durig and his wife were the subjects of a number of resting and
horizontal walking experiments.3 Both the basal and walking experi-
ments were made with the subject in the post-absorptive condition,
that is, several hours after the taking of food. The dry gas-meter
was used and the Zuntz technique. 18 resting experiments and 8
horizontal walking experiments were made with Durig and 11 resting
experiments and 6 walking experiments with Frau Durig, all of these
being in the mountains. In addition the average value is given for a
number of horizontal walking experiments with Frau Durig in Vienna.
Special comment should be made of the extraordinarily heavy appa-
ratus — 16.5 kilograms — carried by Frau Durig, who weighed but 45.7
kilograms. The basal values have been deducted from the values
obtained in the walking experiments and the energy per horizontal
kilogrammeter has been computed; this is given in table 1, page 24.
Observations of Durig, Kolmer, Rainer, Reichel, and Caspari, 1909.—
The extraordinary care which characterizes all of the researches of
Durig is manifest in his classical contributions on the physiology of man
in the Alps; of particular value are his keen criticisms and summation
of earlier research.4 Indeed, nowhere do we find so sharp a recognition
of all of the fundamental tenets of careful experimentation in gaseous
metabolism, and particularly in the physiology of walking with special
reference to the physiology of man in high altitudes, as in this series
of contributions from Durig's laboratory. The observations were all
made with the portable dry gas-meter which, with the equipment,
weighed 11 kilograms. The experiments were made in the morning,
either without food or after taking a cup of weak tea. 32 observations
were made on a level road 200 meters long in Vienna and 12 observa-
z, Loe.wy, Miiller, and Caspari, Hohenklima und Bergwanderungen in ihrer Wirkung auf
den Menschen, 1 Aufl., Berlin, 1906.
2Durig, Denkschriften d. math.-natur. Kl. d. kaiserl. Akad. der Wissensch., 1909, 86, pp. 253
and 254.
3Durig, Archiv f. d. ges. Physiol., 1906, 113, p. 213.
4Durig, Kolmer, Rainer, Reichel, and Caspari, Denkschrift. d. math.-natur. Kl. d. kaiserl.
\kad. der Wissensch., 1909, 86, p. 242.
PREVIOUS RESEARCHES ON GASEOUS EXCHANGE. 19
tions were made on the Semmering. Durig discusses carefully all of
the factors which should be taken into consideration in experiments of
this nature and in the interpretation of their results. Of especial inter-
est is his discussion of the suitable base-line to be deducted from the
values found in the walking experiments. It should be noted that he
adheres to the basal values found with the subject lying, as he considers
the evidence in regard to the standing position wholly inadequate.
His final computations for the energy required per horizontal kilo-
grammeter are given in table 1, page 24.
Observations of Amar, 1910. — In a research on the metabolism of
Arabs,1 Amar made numerous walking experiments with 15 subjects,
who ranged in weight from 59 to 78 kilograms. The experiments were
not made with the subject in the post-absorptive condition and loads
weighing from 45 to 60 kilograms were carried. The Thiry metallic
valve and a dry gas-meter were used. The author gives a very inade-
quate description of his technique. It appears, however, that Amar
probably calculated the heat output of his subjects from the energy of
the food and obtained an approximate control of his results by com-
puting the heat output from the actual determinations of the oxygen
intake and the calorific value of oxygen. Averages computed from the
individual figures given by the author are included in table 1, page 24.
Observations of Amar, 1911. — In a series of walking experiments
reported in 1911, Amar2 used Thiry respiration valves which were con-
nected with a dry gas-meter. The apparatus was placed upon a table,
which was pushed behind the subject as he walked, and samples were
withdrawn and analyzed, apparently for oxygen alone. The experi-
ments were made in the morning, 10 or 12 hours after the taking of
food. Control experiments were made with the subject standing and
also with the subject sitting, Amar noting an increase in the metabo-
lism during standing as compared with sitting. His computations are
based upon the increase in energy expenditure while walking above
that in a state of repose. Especial attention is given in his discussion
to the variations in the load and the economic value of the rate of
walking. The experiments have been criticized by Brezina and Kol-
mer,3 who protest against the lack of information as to the details of the
experiments and the technique and state that the barometric pressure,
temperature, and carbon-dioxide output were apparently not taken into
consideration. An abstract of Amar's results is given in table 1 , page 24.
Observations of Brezina and Kolmer, 1912. — -A series of walking exper-
iments was made by Brezina and Kolmer in Durig' s laboratory in
Vienna.4 In one set of experiments the subject carried on his back a
1Amar, Le rendement de la machine humaine, Paris, 1910; also, Le moteur humain, Paris,
1914, pp. 493 and 494.
2Amar, Journ. de Physiol. et de Pathol. gen., 1911, 13, p. 212.
3Brezina and Kolmer, Biochem. Zeitachr., 1912, 38, p. 132.
*Ibid, p. 129.
20 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
dry gas-meter and the ordinary equipment was used, including the
mouthpiece and valves. This, with additional weights, made a load
of 11 kilograms. In one set of the experiments in which heavier loads
were used, the gas-meter was carried by the subject, but in later experi-
ments the meter was carried by an assistant who walked behind the sub-
ject. All of the experiments were made on a path near the laboratory
and after the subject had taken a cup of tea with sugar. The authors
maintain that the last heavy meal was taken 12 hours previous to the
experiment, and that the influence of the ingestion of food was there-
fore eliminated. In computing the results, a basal value of 1,083 gram-
calories per minute was assumed for the subject. The authors point
out that this is, to a certain degree, arbitrary. It should be noted that
some of the experiments are considered less accurate than the others,
owing to difficulties with the gas-meter. Special emphasis is laid upon
variations in load and in the rate of walking. In a subsequent paper
Brezina and Reichel1 review the earlier paper of Brezina and Kolmer
and make certain corrections in the values. These corrected values
are used by us in our summation of the results of Brezina and Kolmer
in table 1, pages 24 and 26.
Observations of Douglas, Haldane, Henderson, and Schneider, 1913 —
In connection with researches carried out on Pike's Peak by Douglas,
Haldane, Henderson, and Schneider, a number of observations were
made on Douglas, both at Oxford and on Pike's Peak.2 The special
form of respiration apparatus devised by Douglas was used, consisting
of a mouthpiece and a pair of valves connected by tubing with a large
rubber bag carried on the back of the subject. The experiments were
made with the subject lying in bed, in a standing position, and walking
on a horizontal plane at the rate of 2 to 5 miles an hour. The basal
values were assumed to be those measured when the subject was stand-
ing quiet with the muscles relaxed. Apparently some of the lying
experiments were made with the subject in a post-absorptive condition,
while the standing and walking experiments were made after food had
been taken. No attention was paid to the character or amounts of food
eaten and the possible influence upon the measurements, as the observa-
tions were not made primarily for the purpose of studying the absolute
metabolism. A summary of the results is given in table 1, page 26.
Observations of Brezina and Kolmer, 1914- — To carry out the plan
conceived by Durig of studying the metabolism during walking under
every possible condition and to complete their own earlier experiments,
in which they studied the influence of speed and load during walking
on a horizontal path, Brezina and Kolmer made a second research, in
which they studied the influence of the work of ascent upon the metabo-
VBrezina and Reichel, Biochem. Zeitschr., 1914, 63, p. 170.
"Douglas, Haldane, Henderson, and Schneider, Phil. Trans. Roy. Soc. London, 1913, ser. B,
203, p. 185.
PREVIOUS RESEARCHES ON GASEOUS EXCHANGE. 21
lism.1 Numerous experiments were carried out in the Hoschschule
f. Bodenkultur in Vienna, with the treadmill both horizontal and
inclined, and with and without load. Presumably the wet gas-meter
was used. In the load experiments the subject carried a knapsack
with weights in it. In the 15 experiments with the treadmill horizontal,
the rate of walking ranged from 30.1 to 55.2 meters per minute, the
speed being low to correspond with the rate of walking in the experi-
ments with the treadmill inclined. Brezina himself was the subject.
The experiments were made in the forenoon, 1| hours after the taking
of a cup of sweetened tea. The base-line used was probably the values
obtained with the subject lying down, and the Zuntz method for deter-
mining the respiratory metabolism was employed. The caorlies
required per horizontal kilogrammeter are given in table 1, page 26.
Observations of Galeotti, Barkan, Giuliani, Higgins, Signorelli, and
Viale, 1914. — On an expedition to Col d'Olen on Monte Rosa in 1913
Galeotti, Barkan, Giuliani, Higgins, Signorelli, and Viale made a
number of observations on the gaseous metabolism of four individuals
while the subjects were walking on a level.2 Since basal values were
obtained in only one instance, it was necessary to assume these for the
other subjects. The Douglas bag and the Siebe-Gorman valves were
used, except in one experiment when the Tissot valves were substituted.
Strict attention was given to the use of food, certain tests being specifi-
cally made after breakfast. The experiments which are reported here,
however, were made with the subjects in the post-absorptive condition.
An abstract of the values for the horizontal kilogrammeter is given in
table 1, page 26.
SUMMARY OF RESULTS OF PREVIOUS OBSERVATIONS.
In an attempt to arrange in chronological order a mathematical
expression of the values on a comparable basis, we have gathered
together all of the literature available on horizontal walking and sum-
marized the results of previous researches in table 1. In some of the
work, particularly in the earlier observations, certain assumptions were
essential. These assumptions, which were based upon careful analyses
of all of the experiments, upon deductions drawn from the experience of
this laboratory in metabolism experiments, and upon known and recog-
nized errors in technique are, we believe, justifiable and in all proba-
bility are not greatly in error. The table gives the name of the author
and the date of reporting the results of the research ; the name or initials
of the subjects of the walking experiments; the conditions under which
the experiments were made ; the method of measuring the respiratory
exchange; the kind of walking, i. e., in a room, out of doors, or on a
Brezina and Kolmer, Biochem. Zeitschr., 1914, 65, p. 16.
2Galeotti, Barkan, Giuliani, Higgins, Signorelli, and Viale, Reale Accademia dei Lincei, Rome,
1914, and Arch. d. Fisiol., 1914, 12, p. 277.
22
ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
TABLE 1. — Historical summary of walking
Author, date of publica-
tion, and subject.
Condition during
walking.
Method of measuring respira-
tory exchange.
Kind of walking.
Smith, 1859:
Smith
6 hours after
food (?).
5 to 6 hrs. after
food.
1 With food (?)
>With food
Mask for resting; mouth-
piece for walking; spirome-
ter carried.
Tube in mouth; absorption
apparatus in knapsack car-
ried on breast.
Zuntz and Lehmann
Indoors, 11 yds.
in each direc-
tion.
In room, back
and forth.
Zuntz treadmill. .
In chamber
Gruber, 1891:
Gruber
Katzenstein, 1891:
Kohansky
Krzywy
Wellnitz . .
Respiration chamber
Zimm
Sonden and Tigerstedt,
1895:
F. A. W
G. J
L. B
{Not stated
Zuntz and Geppert; dry gas-
meter on back.
do
(Zuntz treadmill,
do
F ..
Schumburg and Zuntz,
1896:
N. Zuntz
Schumburg
N. Zuntz
J
[.. . .do..
In room.
Zuntz treadmill. .
Small plateau in
front of hotel.
Zuntz treadmill. .
do
A. Loewy, J. Loewy,
and L. Zuntz, 1897:
A. Loewy7 ....
J. Loewy7
L. Zuntz7
I
1A few hours after
light, liquid
breakfast.
Moderate break-
fast.
With food
[ do . .
A. Loewy8
J. Loewy8
L. Zuntz8 ....
I
Zuntz; wet gas-meter near
treadmill.
Zuntz
L. Zuntz, 1899:
L. Zuntz . .
Frentzel and Reach,
1901:
Frentzel
Reach
1 After a light
J breakfast.
Without food (?)..
)
> Zuntz and Geppert. .
do
Zuntz and Schumburg,
1901:
B
Durig and Zuntz, 1904:
Dung11
J
Zuntz and Schumburg; dry
gas-meter on back.
. . . do
Free path, out-
doors (?).
In hut
Durig8
N. Zuntz8 ....
Durig13
N. Zuntz13
J
*The summarized data in this table are based on published material cited on pp. 11 to 21.
2Calculated from the data available, assuming a respiratory quotient of 0.85 and 1,609.35
meters per mile.
'Computed with several necessary assumptions, i. e., length of step, 0.680 meter; number of
steps, 80 per minute for second figure as well as for the first; respiratory quotient, 0.85.
4Values computed by Durig (Denkschrift. d. math.-natur. Kl. Akad. Wissensch., 1909, 86,
p. 242), including correction for angle of ascent as indicated by Katzenstein.
6A11 heat values computed by Durig (loc. cit., p. 256), assuming respiratory quotient of 0.85.
Corresponding figures assuming a quotient of 0.75 were: 0.559, 0.373, 0.515, and 0.358.
SUMMARY OF RESULTS OF PREVIOUS OBSERVATIONS.
23
experiments on horizontal plane.
Resting value.
Average
weight
moved.
Distance per minute.
Heat computed per hori-
zontal kilogrammeter.
Range.
Average.
Range.
Average.
Sitting 6 hrs after food
kilos.
92.08
72.00
\ 55.53
1 58.00
] 75.16
[ 57.30
{ 62.73
1 78.25
| 70.09
[ 68.77
f 80.00
| 88.20
1 80.00
72.60
81.10
80.00
f 72.60
\ 81.10
I 80.30
72.94
f 87.10
1 66.40
/ 67.92
\ 72.93
f1291.80
\ 1273.80
[1282.50
/1274.90
\1278.70
meters.
meters.
/ 53.64
\ 80.46
/ 54.40
\ 54.40
74.48
61.80
63.50
65.05
60.60
50.10
65.10
32.00
51.20
42.00
50.10
62.00
60.90
56.40
67.10
60.54
65.24
56.76
98.67
140.11
66.94
35.92
63.95
34.58
76.50
73.50
99.60
85.56
79.93
84.21
62.86
gm.-caLs.
gm.-cals.
20.407
2.468
3.360
3.356
4.526
4.786
4.554
4.426
5.506
s.337
B.465
6.324
6.678
6.616
6.718
.670
.535
.570
.681
.821
.616
9.554
9.653
91.072
.527
.560
.553
.558
10.527
10.509
.527
.584
.663
.668
.774
Sitting, 5 to 6 hrs. after food . . .
Standing, leaning against tread-
mill; with food (?).
Sitting, with food . .
56.00- 92.00
51.00- 75.00
58.00- 71.00
64.00- 66.00
58.70- 62.40
0.506-0.506
62.20- 67.90
.503- .427
[Sitting
P'Ruhewert'1
47.80- 52.40
61.60- 62.40
59.00- 62.80
54.50- 59.20
61.80- 70.21
59.40- 62.04
63.21- 67.33
f 53.45- 59.35
| 92.41-103.40
[135. 74-145. 53
f 57.80- 80.15
\ 31.39- 39.91
/ 60.28- 66.88
1 31.58- 37.23
70.66- 89.21
58.21- 82.38
95.70-111.50
57.34- 95.42
78.66- 80.66
66.26- 91.59
1 60.03- 66.67
6.606- .803
.635- .705
.511- .560
.446- .636
.651- .724
.759- .877
.548- .712
9.538- .561
9.621- .693
91. 015-1. 168
.442- .626
.511- .620
.507- .596
.464- .676
\ Sitting
. .do..
Lying, without food
"Ruhewert"
Lying, with food
Lying, after light breakfast ....
Lying, without food
.474- .571
.448- .681
.574- .714
.633- .699
.742- .796
do
6Values given by Durig (loc. cit., pp. 248 and 261). Figures for treadmill experiments were
corrected by Durig for angle of ascent.
'Experiments conducted at Berlin. Experiments conducted at Col d'Olen.
9A11 heat values calculated by Durig (loc. cit., p. 270).
10Corrected by authors for slight elevation of treadmill. Values for load experiments may be
found on pages 247, 255, and 278 of the original publication, but not corrected for angle of ascent
nExperiments conducted at Vienna.
12Not given by authors; these weights were accordingly computed from other data which had
been obtained by means of the body weight. "Experiments conducted at Capanna Margherita.
24
ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING
TABLE 1. — Historical summary of walking
Author, date of publica-
tion, and subject.
Condition during
walking.
Method of measuring respira-
tory exchange.
Kind of walking.
Caspari, 1905:
K. M
With food
Zuntz
Zuntz treadmill
J. B
do
do . .
do
Zuntz, Loewy, Miiller,
and Caspari, 1906:
Waldenburg
j
Kolmer
Miiller
> Without food ....
Zuntz and Geppert; presum-
Zuntz treadmill..
Caspari
J
ably wet gas-meter.
Dung, 1906:
Frau D.2 .
]
Frau D.3
[Without food ....
Zuntz and Schumbur"" drv
Free path
Durig3
gas-meter on back.
Durig,5 Kolmer,
Rainer, Reichel, and
Caspari, 1909:
Durig2
fWithout food, or
J after cup of
>Zuntz ; dry gas-meter on back .
Outdoors
Durig6
weak, sweet-
[ ened tea.
do
do .
do
Kolmer2
do
do
do
Rainer2
do
.do..
do
Reichel2
do
do
do
Reichel6
do
do
.do
Amar, 1910:
Arabs
With food
Chauveau valve' dry gas-
Circular path.
Amar, 1911:
S. L
10 to 12 hrs after
meter.
Chauveau valve * dry gas-
outdoors.
Brezina and Kolmer,9
1912:
Brezina
food.
12 hrs. after food,
or at least 2
•j hrs. after cup
meter; apparatus on table
moved with subject.
Dry gas-meter carried by
assistant in first series of
experiments and in last 3
ters in each
direction.
Level path out-
doors involv-
of sweetened
tea.
series; in 2d and 3d series,
subject carried meter.
ing turns.
'Average values as corrected by the authors.
Experiments conducted at Vienna.
Experiments conducted at Sporner Alps.
4Not given by the author, but computed from other data in which the body weight was involved.
There is a possible error of about 2 kilograms in this weight.
8The data from these experiments have been grouped for this summary, with special attention
to place and rate of walking.
Experiments conducted at Semmering.
SUMMARY OF RESULTS OF PREVIOUS OBSERVATIONS.
25
experiments on horizontal plane — Continued.
Resting value.
Average
weight
moved.
Distance per minute.
Heat computed per hori-
zontal kilogrammeter.
Range.
Average.
Range.
Average.
Lvinsr.
kilos.
\ 63.18
\ 63.47
65.35
f 74.08
85.10
87.40
[ 81.95
[457.50
\ 63.38
[ 79.25
I" 76.20
[ 76.10
/ 76.30
\ 76.50
94.20
75.40
100.30
f 95.45
\ 95.45
/113.80
\134.10
f 66.00
\ 73.30
f 70.10
70.90
\ 69.90
70.50
[ 70.50
meters.
134.90-142.90
172.00-182.60
122.20-135.70
44.14- 78.85
37.00- 48.45
73.29- 86.52
67.47- 82.69
meters.
139.40
177.30
131.70
60.20
43.16
81.17
76.76
65.00
71.90
95.44
90.10
116.60
126.00
141.80
152.50
102.20
107.90
49.20
66.30
102.50
47.20
87.20
115.80
129.50
88.20
96.30
103.70
79.20
74.80
59.43
55.06
62.40
88.90
111.20
125 . 20
140.80
gm.-cals.
.952-1.018
1 . 154-1 . 184
.906-1.020
gm.-cals.
.979
1.169
.972
J.636
1.845
^eis
!.643
.604
.668
.641
.539
.628
.735
.854
1.023
0.573
.629
.542
.562
.648
.538
.567
.772
.954
.548
.573
.650
7.308
7.323
8.410
8.422
9.534
.574
.743
.846
.971
do
Lying, without food . . .
Lying without food
66.07- 79.63
88.49- 99.63
72 . 30-102 . 30
116.6
1 126.0
1 141.8
[ 152.5
100.70-103.20
105.40-110.30
f 49.2
62.40- 69.20
[100.00-105. 20
f 47.2
1 76.90- 91.30
| 115.8
129.5
59.30-100.80
93.20- 99.20
103.50-103.90
72.00- 90.00
72.00- 80.40
32.40- 89.83
30.33- 78.08
46.10- 72.20
81.80- 98.60
103.10-115.80
120.10-131.20
140.60-141.00
.629- .691
.620- .660
.517- .559
0.628
.735
.854
1.023
0.566-0.587
.622- .636
0.542
0.535-0.591
.635- .659
0.538
0.533-0.584
0.772
.954
0.510-0.583
.563- .591
.641- .659
.257- .402
.310- .335
.315- .577
.365- .535
.4844- .6033
.5615- .5985
.7266- .7684
.8172- .8777
.9347-1.0070
Lvina .
do
do
do
do
do
"Repos" with food
Standing or sitting
V'Erhaltungsumsatz" of 1083
J gram-calories.
7 Averages computed from results given by the author for 15 different subjects. The results
are grouped for the two loads carried.
8A11 heat values computed from the oxygen increment during walking as given by the author
and with an assumed respiratory quotient of 0.85. Assuming a quotient of 0.75, the results for
the two series are: range 0.307 to 0.562; average, 0.400; range 0.356 to 0.521, average 0.411.
9The results in each of these series have been grouped for this summary according to the rates
of walking, the limit of the first group being set at about 80 meters in agreement with the treat-
ment given the material in the original publications. The values for distance and calories are
given as corrected by Brezina and Reichel.
26
ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
TABLE 1. — Historical summary oj walking
Author, date of publica-
tion, and subject.
Condition during
walking.
Method of measuring respira-
tory exchange.
Kind of walking
Brezina and Kolmer,1
1912 (continued):
Brezina
f 12 hrs. after food,
or at least 2
\ hrs. after cup
Dry gas-meter carried by
assistant in first series of
experiments, and in last 3
Level path out-
\ doors, involv-
Do ...
of sweetened
[ tea.
do
series; in 2d and 3d series,
subject carried meter.
do
.
ing turns.
do
Do
do
do
do
Do
^
. .do
do
do
Do
do .
do
do
Douglas, Haldane, Hen-
derson and Schneider,
1913:
Douglas
With food
Douglas bag
fRoom in labora-
1 tory at Ox-
Do
do
. . .do
] ford ; circular
[ path.
{Railway track,
Pike's Peak,
Do
do
do
back and forth.
{Grass track, Ox-
ford, back and
Brezina and Kolmer,
1914:
Brezina
1 y^ hrs. after cup
of sweetened
Zuntz
forth.
Zuntz treadmill. .
Galeotti, Barkan, Giu-
liani, Higgins, Sig-
norelli, and Viale,
1914:
Barkan . . .
tea.
1
[Douglas bag
Half indoors,
Higgins ....
do
half outdoors,
Signorelli .
> Without food ....
I . do.
• • • • "
with a turn
Viale
do
(all indoors in
[ bad weather.)
xThe results in each of these series have been grouped for this summary according to the rates
of walking, the limit of the first group being set at about 80 meters in agreement with the treat-
ment given the material in the original publications. The values for distance and calories are
given as corrected by Brezina and Reichel.
2The body-weights in all the series with Douglas have been computed from the distance and
the total oxygen and the oxygen per kilogram per meter as given by the authors. The subject's
naked weight at Oxford was about 63.5 kilograms; at Pike's Peak, 60.8 kilograms.
SUMMARY OF RESULTS OF PREVIOUS OBSERVATIONS.
27
experiments on horizontal plane — Continued.
Resting value.
Average
weight
moved.
Distance per minute.
Heat computed per hori-
zontal kilogrammeter.
Range.
Average.
Range.
Average.
kilos.
meters.
meters.
ijm.-cals.
gm.-cals.
81.60
37.40- 73.30
53.10 0.4709-0.5278
x.489
j"Erhaltungsumsatz" of 1083
gram-calories.
80.80
1 81.00
' 80.50
78.20- 84.20
92.80- 94.50
105.7
81.50
93.40
105 . 70
.5040- .5411
.6088- .6213
0.7107
.520
.616
.711
81.00
118.1
118.10
.9281
.928
81.00
125.60-129.00
127.30
0.9626-0.9720
.967
[ 91.20
43.50- 77.70
62.00
.4502- .5716
J.506
do
1 91.30
84.60- 94.90
91 .00
.5651- .5933
.581
1 91.10
104.70-105.10
104.90
.7232- .7982
.761
[ 92.25
115.80-115.80
115.80
.9121- .9122
.912
[103.50
32.80- 74.00
54.80
.4766- .5883
!.529
do
1 103. 60 sfi on- qn fin
88.30 ! .5439- .fU3fi
.594
103 . 20
100.0
100.00
0.7256
.726
[lO.S.OO
111.4
111.40
.9143
.914
do
[112.60
37.00- 76.70
55.00
0.5433-0.6391
'.577
J113.00
78.10- 82.20
80.20
.5450- .6778
.611
[113.00
89.90- 94.70
92.30
.8143- .8796
.847
. .do
/123.00
48.60- 68.90
58.80
.5858- .5884
1.587
\123.00
90.9
90.90
0.7747
.775
' 272.45
352.03- 54.18
353 . 38
30.366 -0.448
3.402
Standing, with food
72.77
73.76
77.25- 82.88
102.73-107.83
81.00
105.95
.440 - .490
.523 - .549
.460
.531
72.73
119.90-121.77
120.97
.638 - .682
.656
72.78
134.65-137.87
136.26
.889 - .907
.898
270.71
351.77- 54.98
353 . 64
3.524 - .607
3.562
do..
70.48
77.52- 81.55
79.66
.568 - .634
.600
70.70
102.73-111.32
108.09
.713 - .862
.789
70.88
112.67-116.15
114.53
.768 - .897
.833
70.89
132.77-132.77
132 . 77
.919 - .964
.942
.
' 272.94
353.12- 54.98
353 . 91
3.547 - .609
3.571
... .do..
72.59
79.13- 84.50
82.88
.588 - .600
.595
73.77
105.42-111.58
108.36
.704 - .873
.776
•
74.36
120.43-126.33
123.38
.770 -1.009
.897
73.42
130.63-139.48
136.26
.978 -1.126
1.066
[ 71.60
31.00- 51.70
46.10
.50 - .56
40.53
"Ruhewert"
1 83.80
51.40- 55.20
53.80
.48 - .56
4 .50
93.00
49.40- 52.40
51.10
.42 - .55
4 .50
[104.00
30.1
30.10
0.51
4 .51
1
{79.30
86.70
0.570 -0.395
60 . 448
f Lying, without food
68.00
65.00
5 .550
69.50
86.70
.374 - .398
5 .386
•
78.50
86.70
5 .375
3It was necessary to convert the distances from miles to meters and to compute the heat from
the oxygen consumption.
4Averages of individual heat values given for the groups in the original publication.
6In computing all heat values for Barkan and Viale, the value for lying without food was
assumed to be represented by 255 c.c. of oxygen; for Signorelli, 225 c.c. of oxygen. In one
experiment with Higgins, a corresponding value of 203 c.c. of carbon dioxide and of 265 c.c. of
oxygen was obtained. The weight of the clothing and the Douglas bag was about 7 kilograms
in each case.
28 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
treadmill; the basal or resting value for the individual subjects; the
total weight of the material moved in a horizontal direction, including
the weight of the body, clothing, apparatus, and any supplementary
weight which the subject may have carried; the distance walked per
minute; and finally, the calories per horizontal kilogrammeter.
The speed of the walking, which is shown by the distance walked per
minute, is a factor of considerable importance; the range and average
are therefore both given. Whenever there is a great difference in the
speed for the same subject, a special line is assigned to it. Wide varia-
tions are shown in the average distance walked per minute in the several
researches, the figures ranging from 32 meters in the Sonden and
Tigerstedt experiments published in 1894 to 177.3 meters in an experi-
ment by Caspari reported in 1905.
As a result of a careful analysis of the earlier literature of Durig and
of Zuntz and his co-workers, the unit adopted for expressing the work
of forward progression is the calories required to move 1 kilogram 1
meter or, as we shall here designate it, the calories per horizontal kilo-
grammeter. The range and average are both given for these values,
but the average values have here the greater significance, and it is the
last column of the table which we shall particularly consider. Examin-
ing these data, we find that they range from 0.308 gram-calorie in the
series of experiments made by Amar and reported in 1910 to 1.169
gram-calories in the experiment by Caspari published in 1905. Con-
sidering the varied technique, there is, on the whole, a rather remark-
able agreement of the values found for the movement of 1 kilogram of
body-weight per meter in a horizontal direction, particularly when we
consider those values obtained at moderate walking speed.
Comparing the data for the average distance walked per minute and
those for the average calories per horizontal kilogrammeter, we find
that the rate of walking has a considerable influence upon the results
and that the higher values are invariably found with the greater speeds,
although the reverse is by no means true. In general, when the rate of
walking does not exceed 80 to 90 meters per minute, the values lie
between 0.3 and 0.7 gram-calorie, with a distinct tendency for them
to approach 0.55 gram-calorie. This value has been especially con-
sidered by Durig in his admirable review of the literature of this
subject. It is clear, then, that we have here to do with an intimate
relationship between the rate of walking and the expenditure of energy
required to move 1 kilogram 1 meter in a horizontal direction, and that
the superimposed load has relatively little influence upon the results.
METHODS AND APPARATUS. 29
METHODS AND APPARATUS FOR STUDIES OF
MUSCULAR WORK.
Judging from the results as published in the earlier literature and
summarized in the preceding section, there is apparently little choice
as to the various methods of study. A large majority of the observa-
tions have been made with the Zuntz respiration apparatus or some of
its modifications; it is obvious that any criticisms applying to this
apparatus affect greatly the averages of the values obtained with it.
While the construction of the Zuntz apparatus and the various types
of valves, particularly the later form of valve used by Durig, is such as
to eliminate resistance as far as possible, nevertheless the employment
of this type of apparatus for studying muscular work is distinctly open
to criticism.
The use of a wet gas-meter of the size ordinarily employed with the
Zuntz respiration apparatus may be seriously objected to for muscular-
work experiments, since in these experiments the volumes of expired
air may exceed 80 or 90 liters per minute. The calibration of such a
meter at the rate of ventilation used in severe-work experiments is
by no means a simple matter, the ordinary method being to allow the
water in a 10-liter spirometer to flow out and draw the air in after it.
On the ordinary Elster gas-meter 10 liters correspond to one or at most
two revolutions of the drum, and the possibilities of error at the begin-
ning and the end in tests of this kind are obvious. Indeed, both Durig
and Zuntz have recognized this difficulty and, to avoid errors in the
measurement of the large volume of air expired from the lungs, have
made experiments with a very large gas-meter formerly used in studies
with horses. If the value obtained for the volume of air be too small
(and the error, if any, would be in this direction), obviously that for the
total metabolism will likewise be too small, and hence the values com-
puted for the horizontal kilogrammeter will be too low.
The importance of knowing the energy requirement of the body for
direct forward progression is so great as to justify further observations
upon it, particularly if an apparatus is used in which an entirely dif-
ferent principle is employed for measuring the metabolism. One of
the main lines of research planned for the Nutrition Laboratory is a
study of muscular work in its various phases. Obviously innumerable
problems, of both physiological and economic importance, can be
studied with suitable apparatus. A special calorimeter has been
constructed in this laboratory for research on muscular work, but it is
not yet ready for actual use. Prior to experimentation with this
calorimeter, it seemed important to make a number of preliminary
studies of the metabolism during muscular work with the universal
respiration apparatus. This apparatus had previously been used in a
study of the metabolism incidental to riding a bicycle ergometer, in
30 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
which it was shown that it was capable of measuring the metabolism
with an oxygen consumption as high as 3 liters per minute.1 Careful
control tests of the apparatus have proved conclusively that, so far as the
mechanical construction is concerned, the measurement of the carbon-
dioxide production and the oxygen consumption is accurate.
As a part of the plan for studying the metabolism during the various
phases of muscular work, a special type of treadmill was devised and
constructed in this laboratory several years previous to the present
research. Certain features of this treadmill, which will be described
subsequently, make it especially applicable for use in experiments with
men. Having, therefore, an exceptionally satisfactory treadmill and
a respiration apparatus capable of measuring the metabolism incidental
to severe muscular work, it was possible, in 1913-14, to make a study
of the metabolism of a subject while he was walking on a level.
As soon as the respiration calorimeter for muscular work is ready for
use, the treadmill will be placed inside this apparatus and certain of
the experiments repeated. The indirect calorimetry computed from
the gaseous exchange as measured by the respiration apparatus can
thus be controlled by direct determinations of the energy output.
This control is of particular importance, since the use of any form of
respiration appliance, such as a mouthpiece or nosepieces, is open to
legitimate criticism in that the use of such artificial methods of breath-
ing, particularly with a very great ventilation of the lungs, may lead to
a disturbance in the mechanics of ventilation, thus causing a distur-
bance in the respiratory exchange. Although the universal respiration
apparatus has been carefully controlled as to the measurement of both
carbon dioxide and oxygen, nevertheless if there is a disturbance in the
mechanics of ventilation, as, for instance, an over-ventilation of the
lungs, there may be a considerable amount of carbon dioxide exhaled
that was not simultaneously produced. The retention of carbon
dioxide by altered respiratory mechanics is also not improbable. By
means of the studies with the respiration calorimeter, therefore, it will
be possible not only to determine the metabolism by direct calorimetry,
but also to obtain the gaseous exchange with free breathing without
the use of either mouth or nose appliance.
It should furthermore be borne in mind that while the method of
computing the calorimetry from the gaseous exchange has, according
to our experience up to the present time, given highly satisfactory
results with muscular repose, there is always the possibility of a dis-
turbance in the character of the metabolism during severe muscular
work and a consequent disturbance in the relationship between the
gaseous exchange and total heat production. It is thus seen that the
final tests with the respiration calorimeter are essential for a complete
understanding of this problem. On the other hand, the previous
Benedict and Cathcart, Carnegie Inst. Wash. Pub. No. 187, 1913.
DESCRIPTION OF APPARATUS. 31
research with the professional bicycle rider, in which the universal res-
piration apparatus was employed, was so successful and the problem of
the metabolism during the work of forward progression is so important
that, pending the completion and testing of the special calorimeter, the
study of this problem with the universal respiration apparatus and the
treadmill has seemed entirely justifiable.
DESCRIPTION OF APPARATUS USED IN THIS RESEARCH.
UNIVERSAL RESPIRATION APPARATUS.
The researches of Zuntz and his co-workers have shown that in walk-
ing at a somewhat high rate of speed and carrying a load, the amount of
muscular exertion required, even on a level path, is very considerable,
approximating that required for bicycle riding under severe stress.
Obviously, therefore, any respiration apparatus used in a study of the
metabolism under these conditions must be capable of accurately
measuring a maximum oxygen consumption per minute of 3,000 c.c.
and a maximum carbon-dioxide production of 2,500 c.c. Fortunately
the modified form of the universal respiration apparatus employed by
Cathcart had already demonstrated its ability to fulfill these conditions.
The form of apparatus used in this later research was therefore essen-
tially that employed for the earlier study.1 A general view of the
apparatus with its relations to the subject and the accessory apparatus
is shown in figure 1.
Since the completion of the research on the bicycle rider, various
minor modifications have been made in the apparatus, chiefly with a
view to facilitating operation and contributing to its accuracy. Certain
other changes were also necessary to adapt it to the type of experiment
planned for this research, namely, walking upon a treadmill at varying
rates of speed. These changes were considered of sufficient importance
for us to give here a schematic outline of the apparatus as actually
employed in the research. (See figure 2.)
As will be seen from the diagram in figure 2, by turning a 3-way
valve N, the subject, breathing through a mouthpiece P, can be con-
nected with the ventilating air-current, which is kept in motion by a
rotary blower. The air leaving the blower is first passed through a
glass Williams bottle which serves as a safety trap against back-suction
of acid. The air is next forced through two Williams bottles, each
having a capacity of 2.5 liters and half filled with sulphuric acid,
which removes the moisture from the air. The ventilating current
is then deflected by means of the 2-way valve V1 into either one of two
xBrezina and Kolmer in a recent paper from Durig'a laboratory (Biochem. Zeitschr., 1914, 65, p.
33) have questioned the accuracy of the respiratory quotients obtained with this apparatus by
Benedict and Cathcart in their study of a bicycle rider. Dung in a private communication says
that the method used by Benedict and Cathcart for obtaining the respiratory quotients was accu-
rate and that the criticisms of Brezina and Kolmer were founded upon an insufficient study of the
results.
32
ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
carbon-dioxide absorbing systems. Each series of absorbers include
two bottles filled with moist soda lime for absorbing the carbon dioxide,
and also a small Williams bottle, containing sulphuric acid to absorb
the moisture given up to the dry air by the soda lime. The air, which
is at this point free from carbon dioxide and water, passes through the
2-way valve Vz, and after being moistened in a small Williams bottle
to a comfortable degree for respiration, it continues until it passes
FIG. 1. — General view of apparatus used for walking experiments, with subject in position.
A, absorption apparatus; B, treadmill; C and D, oxygen supply; E, step counter and
accessory apparatus.
by the opening of the tube connected with the mouthpiece P and into
the tension equalizer. This tension equalizer is a large copper can,
over the top of which is fitted a rubber bathing-cap. From this copper
can the air finally returns to the intake side of the blower, oxygen being
admitted as required from a cylinder of the gas. Thus we have a com-
plete closed-circuit system, with the rubber bathing-cap acting as a
tension equalizer to compensate for changes in the volume of air as the
subject breathes in and out.
DESCRIPTION OF APPARATUS. 33
The algebraic increase in weight of the soda-lime bottles and the
following Williams bottle in the carbon-dioxide absorbing system gives
the weight of the carbon dioxide absorbed during the experimental
period. The volume of oxygen introduced may be determined from
the loss in weight of a small cylinder or, as indicated in figure 1 , meas-
ured by conducting it from a large cylinder through a carefully calibrated
gas-meter which is immersed in water to prevent sudden fluctuations in
temperature. To prove the efficacy of the soda lime as an absorbent,
a part of the air current may be deflected through two petcocks and
passed through a solution of barium hydroxide in a small Erlenmeyer
flask. The slightest trace of carbon dioxide will produce a turbidity
in the solution.
To eliminate the effect of the long dead space between the mouth-
piece, P, and the main ventilating air-pipe, a supplementary pipe E is
connected from a point near the mouthpiece to the main air-pipe. By
this means the air-current may be deflected so that it will pass directly
by the mouthpiece and within a few centimeters of the lips of the sub-
ject. The rubber tubes connecting the subject with the ventilating
system are of sufficient length and flexibility to permit considerable
lateral and vertical head-motion by the subject while walking, this
being essential to his comfort.
In actual experimenting, before the experimental period is begun,
the 3-way valve N is so turned that the subject breathes room air.
Then, at the end of a normal expiration, the 3-way valve is again turned,
connecting the subject with the main ventilating air-current as seen in
the diagram. Immediately afterwards the valve M (which has previ-
ously been open, giving free passage of the air into the metal tee leading
to the tension equalizer) is also turned, thus deflecting the air-current
through the supplementary pipe E, so that it passes near the mouth of
the subject.
Before connecting the subject with the ventilating system, the motor
is started to equalize pressure throughout the system and then stopped.
Sufficient oxygen is next admitted to distend the rubber bathing-cap
until a slight positive pressure is observed on the manometer. On
starting the blower again, the rubber bathing-cap sinks somewhat, due
to the compression of the air in forcing its way through the sulphuric
acid and the various absorbing-vessels. At the first inspiration the
rubber cap sinks down into the can, rising again with each expiration.
As the oxygen is consumed, the height to which the rubber cap fills
decreases and oxygen is admitted to keep the fluctuations of the
bathing-cap to approximately the same range. At the conclusion of
the experiment, the valve M is first turned and shortly afterwards the
valve N is also turned, always at the end of a normal expiration. At
this point the experimental period is concluded so far as the subject is
concerned. The motor is next allowed to run for a minute or two to
34
ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
sweep out completely the carbon dioxide in the system. When the
motor is stopped sufficient oxygen is admitted to bring the tension to
the original point; the volume of air in the system is then exactly the
same as at the beginning. The carbon-dioxide absorbers and the accom-
panying Williams bottle are weighed and a reading taken of the amount
of oxygen which has passed through the gas-meter, the data being used
subsequently for computing the carbon dioxide produced and the
oxygen consumed during the experimental period.
MANOMETER BaOH, MOISTEN ER
HaS04 H2S04 TRAP METER
FIG. 2. — Schematic outline of universal respiration apparatus.
The general course of the ventilating current is shown by arrows. P, mouthpiece; N, 3-way
valve connecting subject with ventilating current; V1 and V2, 2- way valves for carbon-
dioxide absorbing system; M, valve connecting with supplementary pipe E for eliminating
the dead-air space; S, petcock connection for tambour and kymograph for recording the
respiration.
TREADMILL.
In many of the earlier investigations for measuring the carbon-
dioxide output and oxygen consumption of a walking man, the subject
has been obliged to carry a respiration apparatus upon his back or
drag behind him a long tube attached to the breathing appliance.
In other studies the apparatus has been pushed along behind the
subject by an assistant. Obviously none of these methods are suitable
for experiments in which there is rapid movement. Furthermore,
while we have no desire to minimize the value of the Zuntz apparatus—
an apparatus which has contributed largely to our knowledge of the
physiology of man, particularly for high altitudes — it should be said
that the transportation of an unwieldy gas-meter and accessory appa-
ratus by a subject is open to serious objection. It has been shown
DESCRIPTION OF APPARATUS.
35
by Zuntz and his co-workers that a subject may be trained in a rela-
tively short time to carry such an apparatus successfully; nevertheless
its transportation is at best difficult, and the method is more fitted for
studies of that type of walking in which loads would normally be carried
upon the back. Both Zuntz and Durig have shown that they recognize
this fact, as they have made studies in which the gas-meter was not
carried by the subject, and the walking was done upon a treadmill.
Several years previous to our research, Mr. E. H. Metcalf, then a
member of the staff of the Nutrition Laboratory, designed a tread-
mill and had it constructed under his supervision in the machine-shop
of the Laboratory. This treadmill was used for the first time in the
research carried out in 1913-14 and the fact that it satisfactorily sus-
tained a severe test at this time testifies to the designing ability of Mr.
Metcalf and the constructive skill of Mr. W. E. Collins, the mechan-
ician of the Laboratory. A general view of the treadmill and its dispo-
sition with regard to the other apparatus is shown in figure 1. A more
detailed perspective drawing is given in figure 3.
FIG. 3. — Treadmill designed by E. H. Metcalf.
The endless leather belt travels over two wooden pulleys A and B, the actuating mechanism
being an electric motor. The tension on the belt may be adjusted by the bolt and nut C.
A revolution counter is shown at R.
The treadmill is provided with an endless belt, 60 cm. wide, 435
cm. long, and approximately 10 mm. thick. This belt travels over
two wooden pulleys, A and B, having a width of 60 cm. and a
diameter of 41 cm. The pulleys are supported on ball bearings at the
ends of a wooden frame. On the rear pulley is attached a sprocket-
wheel, which connects with the reducing-gear actuated by a one-half
horsepower electric motor. The tension on the belt may be easily
adjusted by means of the screw C, thus preventing the belt from slip-
ping. To support the belt between the pulleys and provide a surface
for the man to walk upon, steel tubes, 46 in number, with an external
diameter of 25 mm. and a length of 61 cm., are set into a steel frame-
work, the distance between the centers of the tubes being 27 mm.
These steel tubes are fitted at each end with annular steel ball bearings.
36 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
The detail of the bearings is given in figure 4, which shows the method
of support on the angle frame of the treadmill. The thick belt thus
rests upon a rolling, frictionless surface throughout the whole length of
the space over which the man is to walk, providing a substantial,
perfectly smooth path for the subject. It is impossible to feel the
numerous steel rolls, as the space between them is so small. The
leather belt gives a particularly satisfactory footing. The speed of the
motor may be modified at will and tests may be made at rates of speed
varying from less than 50 meters per minute, the equivalent of a very
slow walk, to 150 meters per minute, or a rapid walk, if not, indeed,
running.
Since the driving of the treadmill belt is from the rear wheel, all tend-
ency to slip is at this point. Consequently, by counting the revolutions
of the forward wheel, where no slip can possibly take place, we have an
accurate measure of the total distance traveled. Upon the periphery
of the forward wheel are attached two revolution counters (one on
each side)1 which can be read intermittently. One runs continuously;
the other may be connected or disconnected at will. In use, the
subject walks upon the treadmill for several minutes before the experi-
mental period commences. At the exact moment of beginning the
measurements of the respiratory exchange, one of the revolution
counters is put in action, so that the distance covered during the
period is accurately known. It is thus unnecessary to assume con-
stancy in the revolution of the motor or to apportion the distance
walked during the period from the total measurement of the revolutions
of the front wheel during the entire time the subject is walking.
Considering the number of the various bearings and the size of the
apparatus it produces much less noise and vibration than any treadmill
that we have thus far seen. By means of adjusting screws at the for-
ward end of the treadmill, which are not shown in figure 3, any desired
elevation can be readily secured. In this research, however, the tread-
mill was invariably used in a perfectly level position. At the date of
writing (June 1915), after two years of use, the apparatus shows no
signs of wear and gives most satisfactory service.
ACCESSORY APPARATUS.
The universal respiration apparatus and the treadmill provide accu-
rate measurements of the total carbon-dioxide production and the
oxygen consumption and of the distance walked by the subject. In
addition to this, certain observations are important, particularly in
studying the physiology of walking, and it was therefore necessary to
have some means of recording accurately the respiration, the pulse,
the number of steps taken by the subject, and the height to which the
body was raised with each step.
'But one of these (R) is shown in figure 3.
DESCRIPTION OF APPARATUS. 37
METHOD OF RECORDING THE RESPIRATION-RATE.
The rise and fall of the rubber bag or tension equalizer with each
expiration and inspiration can be readily counted by an observer,
thus giving an admirable index of the respiration. As a matter of
fact, during the conduct of a severe-work experiment of this type, the
other observations are so numerous that it is at best very difficult for
an observer to concentrate his attention upon such counting. A
tambour has therefore been connected to the petcock S (see fig. 2)
which is moved by the difference in pressure existing in the connection
between the mouthpiece and the tension equalizer. With each exhala-
tion a slight pressure is exerted upon the tambour which records upon
a kymograph drum. Subsequently an accurate count of the number of
respirations per minute and for the entire experimental period may be
made from the tambour record and that of a time marker.
METHOD OF RECORDING THE PULSE-RATE.
The important relationship between total metabolism and the pulse-
rate, which has been so frequently observed in this Laboratory, made it
desirable to secure records of the pulse-rate of the subject during the
walking periods. The difficulties experienced in securing counts of the
pulse-rate in the earlier research with the bicycle rider have been freely
commented upon in the publication giving the report of that study, and
it was hoped that some graphic method could be found which would give
accurate records of the pulse-rate of a walking man. Unfortunately
such a method was not available at the beginning of our research, and
counts were therefore made at the wrist or with a stethoscope. Even
with a stethoscope at some distance, as employed by Krogh,1 the noise
of the treadmill was such as to make the counting of the pulse-rate
extremely difficult. Various forms of tambours2 were also experimented
with in an attempt to register the pulse graphically, but without result.
Finally, by using body leads and the Bock-Thoma oscillograph or the
Einthoven string galvanometer, we were able to secure graphic records
of the pulse-rate of the subject while he was walking upon the treadmill.
Great difficulty was experienced in such photographic registration
with the delicate oscillograph and string galvanometer, for not only
were there leakages of the 220- volt current used for the motor, but also
a static charge on the rapidly revolving belt. Various devices were
used for obviating these difficulties, such as having the subject wear
rubber-soled shoes and even rubbers over the shoes, but with little
success. Finally a metallic brush was made of a piece of brass tubing,
69 cm. long, to which pieces of brass chain, 7 to 9 cm. long, were
attached at intervals of approximately 1.5 cm. This brush was so
attached to the treadmill that the ends of the chains lay upon the
, Skand. Archiv f. Physiol., 1913, 30, p. 375.
2Bowen, Contributions to Medical Research dedicated to Victor Clarence Vaughan, June 1903,
p. 462, Ann Arbor, Mich.
38
ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
surface of the leather belt. As one end of the chain brush was grounded
to the brass tube, when the ends of the chain dragged over the surface
of the revolving belt the stray electric currents were picked up and
grounded. Satisfactory records could thus be obtained. Unfor-
tunately the conditions of the experimental work in the Laboratory
at that time prevented our freeing a galvanometer and oscillograph
for the particular purpose of determining the pulse-rate; consequently
records could not be regularly secured. Indeed, the few observations
obtained were of so striking a character that we can not adequately
discuss them in this monograph.1
STEP COUNTER.
With a steady electric current, the rate of revolution of the treadmill
per minute is presumably fairly constant and the length of the steps
in ordinary walking is also doubtless approximately the same ; neverthe-
less it is important to show in these tests the exact number of steps
-taken, so as to indicate the distance per step and thus furnish an added
factor for analyzing the mechanics and physiology of walking. To
count the steps automatically was imperative, as even with several
assistants an accurate record of the steps during exceedingly rapid
FIG. 4.
FIG. 5.
FIG. 4. — Detail of ball bearing for steel tubes on the treadmill.
FIG. 5. — Step counter. A pulley A is attached to the extended shaft of a revolution counter;
a small cord passes over this pulley and is protected by a guard C. The shaft automat-
ically stops at B and B'.
walking would be very difficult to obtain. A small device was there-
fore employed which counted automatically each vertical motion of
the body produced in walking.
To a belt about the waist of the subject was attached a cord leading
over two pulleys on the ceiling to a small spring which maintained
a tension on the cord. The general arrangement of this device is shown
in figure 1 and the details in figures 5 and 6. At each step the sub-
ject lifted the body a certain distance and lowered it again. Advan-
tage was taken of this lifting and lowering of the body to raise and lower
a small weight (E, fig. 6) at the end of a cord which rested upon a pulley
(A, fig. 5, and D, fig. 6) on the shaft of a revolution counter (see fig. 5).
'See pp. 85 and 92.
DESCRIPTION OF APPARATUS.
39
Automatic stops, B and B', controlled the distance traveled by the
pulley. At each upward movement of the body the cord was lowered
and the counter pulled in one direction to the stop, the cord simply
slipping over the pulley if the movement continued. As the body
returned to its ordinary position, the weight drew the counter back to
the second stop. In this way each upward movement of the body was
accurately recorded.
Records obtained with this counter of the number of steps taken by
one of our subjects in several walking experiments are given in table 2.
These are compared with the number of steps counted for the same
periods from kymograph records obtained by a method subsequently
described.1 A large number of controls, which were made by counting
the movements of the body from the kymograph records and by obser-
vations of the counter, showed that this step-counter could be relied
upon.
TABLE 2. — Comparison of steps recorded by step-counter with those counted from
kymograph records.
Total number of steps.
Distance
Steps
Date.
Period
(meters)
per
Counted from kymo-
No.
per
minute.
minute
(counter).
Counter
graph record by
recorci.
Observer
Observer
I.
II.
1914
Apr. 24 ....
[1
76.4
78.4
116.2
117.1
1,687
1,452
1,700
1,454
1,704
1,444
Apr. 27
(I
73.5
78.1
114.8
116.0
1,596
1,442
1,588
1,418
1,596
1,400
1
114.5
138.3
1,470
1,472
1,472
May 4 ....
2
109.1
133.9
1,491
1,508
1,516
I 3
102.0
127.8
1,459
1,476
1,458
f 2
106.0
133.1
1,338
1,340
1,356
May 5. ...
J i
\
102.6
126.5
1,402
1,428
1,420
(4 103 . 6
126.3
1,269
1,274
1,262
METHOD OF MEASURING HEIGHT TO WHICH THE BODY IS RAISED.
One factor of the mechanics of walking has hitherto been neglected
for the most part by writers, particularly when studies of the gaseous
metabolism have been made, that is, the height that the body is raised
during the process of walking. At each step the body is raised and
lowered a distance of approximately 25 to 50 mm., and even higher in
running.2 In any careful research on the physiology of walking in
which the efficiency of the body for moving a certain weight a certain
distance forward is studied, it is necessary to note the height of this
upward movement. For this purpose Dr. Carl Tigerstedt used a device
'See p. 40.
2See table 20, p. 98.
40
ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
which, in principle, was much like that used by him in studying; mus-
cular work done with the foot.1
This apparatus, shown in figure 6, consists of a small pointer A,
traveling on a brass block between two upright guides. The cord G,
attached to the pointer, passes over a pulley to the belt of the subject,
as shown in figure 1. The spiral spring F, previously referred to
in the description of the step-counter, keeps a tension upon the cord.
Obviously as the body is raised the tension of the spiral spring draws
the pointer down and as the body is lowered the cord draws the pointer
up. Each upward and downward movement of the body may be
recorded on a rotating kymograph drum, thus giving a graphic record
of the character of each step. A typical record is given in figure 7.
It can be seen that the height to which the body is lifted may be
obtained from the kymograph record by measuring each downward
stroke of the pointer and adding the sum of the
values. Experimental conditions prevented us
from using a kymograph with a rapidly rotating
drum or a long paper kymograph, and the con-
sequent superimposing of the records shown in
figure 7 obviously makes the counting of the
number of steps somewhat difficult; neverthe-
less it is possible and has been done in a number
of instances (see table 2). By measuring several
points in the curve, an approximate average
height of step may easily be obtained; these
averages may then be multiplied by the total
number of steps recorded on the step-counter
and the distance to which the body is raised
computed.
In an attempt to sum up these upward move-
ments by means of some automatic arrangement,
a special form of work adder-wheel was devised
for the purpose. This work adder-wheel, which
is shown as B in figure 6, relied upon the friction
FIG. 6. — Apparatus for recording the height to which the body is
lifted, and step-counter with connections.
The cord G, connected with the body of the subject, passes over a
grooved wheel B attached to the shaft of a revolution-counter
C, a pawl p, preventing backward motion. It then passes
to a pointer A (the marker of Dr. Carl Tigerstedt), tension
being supplied by the light spring F. An upright cord
travels over a grooved pulley on the step-counter D, with the
tension produced by the small weight traveling in a tube E.
The height to which the body is raised at each step is thus
recorded in a dual manner, first, by the excursions of the
pointer A over a kymograph drum and second by the accumu-
lated movement of the wheel B.
'C. Tigerstedt, Skand. Archiv f. Physiol., 1913, 30, p. 299.
FIG. 7. — Typical kymograph record showing character of step.
The upper line shows the admission of oxygen to the apparatus, each section representing 1 liter;
the second line the steps taken by the subject; the third line the respiration; and the lowest line the
time in minutes.
DESCRIPTION OF APPARATUS. 41
of a cord passing over a groove in the wheel to rotate it in one direction
as the body was lifted, a pawl p preventing any backward motion.
When the body returned to the normal position, the cord slipped over
the pulley without producing any movement of the wheel. Each
upward movement of the body accordingly resulted in a forward
motion of the wheel. The work adder-wheel was directly connected
to the shaft of a revolution-counter, and a record of the total move-
ment of the wheel was thus obtained. (See C, fig. 6.) The total dis-
tance the body was raised would theoretically be that found by multi-
plying the number of revolutions of the wheel by its circumference.
At the very rapid rate of walking used in some of these experiments,
great difficulty was experienced in the earlier development of the appa-
ratus in securing an accurate record. The cord would frequently
slip and there was considerable reverse movement, for it was not easy
to find a pawl arrangement which would work perfectly. This reverse
movement or "back-lash" was not overcome until practically the end of
the series of observations; recently, however, a very thin laminated
spring has been used as a pawl, which has practically eliminated this lost
motion. The apparatus as described represents the completed form.
As a matter of fact, in many of our experiments we were unable to use
the records obtained from this wheel. The height to which the body
was raised was therefore determined by the method previously referred
to, i. e., measuring on the kymograph curve the general average dis-
tance to which the body was raised and multiplying this by the record
of the number of steps on the step-counter.
In order to have these measurements of absolute value, the distance
traveled by the pointer on the kymograph or that traveled by the cord
passing over the work adder-wheel must represent exactly the distance
over which the body is elevated or lowered. This assumes that there
is no disturbance in the attachment of the cord to the body and that
the tension of the spring is such as to prevent any diag or inequality
in the movement of the pointer over the drum. As may be seen from
the kymograph curve reproduced in figure 7, the constancy in the
movement of the pointer was very satisfactory. On the other hand,
the method of attaching the cord to the subject was certainly open to
serious criticism. Wire was used for the most part, violin string being
substituted for such portions as passed over the flexible parts, thus
minimizing the tension and the danger of alterations in the length.
There was, however, opportunity for considerable flexibility in the play
of this cord at the point where it was attached to the belt holding up the
trousers of the subject; accordingly, the records obtained with the kymo-
graph and with the work adder- wheel are without doubt invariably some-
what too small and the body was in all instances raised to a higher point
than that indicated in table 2. The expediency of attaching a wire
direct to the body by means of surgeon's plaster was not resorted to,
although the omission was undoubtedly an error in our observations.
42 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
PLAN OF RESEARCH.
While this investigation was undertaken primarily with the object of
studying the metabolism of walking on a level, certain preliminary
observations were necessary, particularly for the purpose of establishing
a base-line for comparison with the metabolism during walking. As
has previously been stated, certain investigators, in studying the
metabolism during walking, have been inclined to employ as a basis
of comparison the metabolism determined with the subject in the lying
position and without food in the stomach, i. e., maintenance metabo-
lism. Many attempts have also been made to study the metabolism
with the subject in the standing or the sitting position, these values
being deducted from the total metabolism obtained with the subject
walking, the increment being considered as due to the work of forward
progression. It was therefore necessary in our research to study the
metabolism not only during walking but also under other conditions,
thus increasing the number of problems to be studied.
A considerable number of experiments were carried out with the
subject standing in different positions, those used being (1) with the
subject standing with the body relaxed, as one would stand quietly
without external support; (2) leaning against a support at the back;
(3) leaning upon a staff; and (4) standing with muscles tense in the
position of "attention." By determining the metabolism in these
various resting or standing attitudes, all conceivable base-lines could
be obtained. Furthermore, it was found that during experiments with
rapid walking there was considerable lateral motion of the arms, as is
the habit with many walkers, particularly professional pedestrians.
Consequently certain experiments were made with the subject standing
and swinging the arms from side to side as in a fast walk, but without
moving the feet. A number of observations were also made of the
metabolism with the subject sitting, with the idea that the values thus
obtained might be used for the basal metabolism. As a matter of
fact, only a few of the sitting experiments were made with the subject
in the post-absorptive condition and the values secured have not been
used for actual comparison purposes.
The main object of the research was, of course, the study of the
metabolism during walking and specifically the study of the increase
in the metabolism due to walking at increasing speeds. In the series
of walking experiments, therefore, the subject was required to walk at
a very slow speed, then at a medium speed, and finally at a very fast
speed. In a few experiments the subject actually ran, thus giving data
for comparing the work of forward progression while the subject was
walking with that while he was running, two entirely distinct methods
of forward progression. Certain observations were also made regard-
ing the effect upon the metabolism of fatigue due to long-continued
PLAN OF KESEAKCH. 43
walking, the subject being required on several days to walk for a con-
siderable length of time.
While, in common with several other investigators, we have believed
that the most sharply defined results can be obtained in experiments
without food, nevertheless the experimental conditions were such as to
make it relatively simple for us to obtain values after the ingestion of
food. With this end in view, we made specific studies of the metabo-
lism under the various conditions of standing, walking at various
speeds, running, and after fatigue, not only when the subject was with-
out food in the stomach but also after food had been taken. The
experiments carried out after food duplicated the experiments with the
subject in the post-absorptive condition; it was therefore possible to
note whether or not there was a summation effect on the metabolism
due to the ingestion of food and to the work.
While in some of the experiments the diet was uncontrolled, in a
number of them it was prescribed. The constituents of the meal
varied widely in these latter experiments, a special protein diet being
supplied on some days, on others a diet containing an excess of fat, and
again a diet with a large proportion of carbohydrate. The results
of these experiments accordingly gave data as to the effect of a special
diet upon the metabolism during walking.
This, in brief, was our plan of research at the beginning of the series
of observations. Incidentally a number of other important physio-
logical details were developed as the research progressed. These will
be taken up specifically in the discussion of the results of the experi-
ments.
44 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
GENERAL ROUTINE OF THE EXPERIMENTS.
It will be seen from the foregoing that the experiments irithis research
fall naturally into four classes: standing experiments, sitting experi-
ments, walking and running experiments, and experiments with food.
From the earlier experience of Cathcart with a subject riding a bicycle,
it seemed inadvisable to attempt the establishment of a standard lest-
ing base-line to be deducted from the total metabolism of the subject
while walking. It was therefore decided that each morning, prior to
the walking experiment, measurements should be made of the standing
resting metabolism; consequently the research included a large number
of standing experiments.
STANDING EXPERIMENTS.
The respiration apparatus used for this research and previously
described was designed more especially for measuring the large amounts
of carbon dioxide exhaled during severe muscular exercise, and was, in
consequence, fitted with two soda-lime bottles, each of which must be
weighed. If only the resting metabolism had been determined, a
slightly different arrangement would have been preferred, with the use
of but one soda-lime bottle, a spirometer form of apparatus being
substituted for the rubber bathing-cap and tension-equalizer. Never-
theless, since the resting metabolism with the subject standing was to be
used primarily as a base-line to be deducted from the greatly increased
metabolism during walking, it was considered that this method of
measuring the metabolism during standing would be sufficiently
satisfactory for the purpose, and hence the standing metabolism was
determined on exactly the same apparatus as that used in the walking
experiments. As a matter of fact, the experiments made by Cathcart,
and more especially those of Carpenter,1 have shown that the tension-
equalizer form of the unit apparatus gives as accurate measurements of
the metabolism during rest as does the spirometer type. In this par-
ticular apparatus, however, we could readily have dispensed with the
second soda-lime bottle.
After arriving at the Laboratory, the subject arranged his clothing
for an ordinary walking experiment and assumed the standing position
on the treadmill, this position being maintained for some time prior to
the actual experimentation. After the effect of the slight exertion of
coming to the Laboratory and of ascending the stairs had passed away,
the mouthpiece was inserted, the noseclip attached, and at the proper
time, i. e., at the end of a normal expiration, the 3-way valve connecting
the subject with the ventilating system of the respiration apparatus
was turned. The experiment was then continued in the usual manner
Carpenter, Carnegie Inst. Wash. Pub. 216, 1915, pp. Ill to 118.
GENERAL ROUTINE OF THE EXPERIMENTS. 45
for approximately 15 minutes. At the end of a normal expiration the
valve was again turned and the experiment was completed. During
the entire experiment oxygen was admitted regularly from a cylinder,
the gas being passed through a carefully calibrated Bohr gas-meter
immersed in water. At the conclusion of the experiment the ventila-
tion was continued for a few minutes to insure the thorough sweeping
out of all the carbon dioxide; finally the tension-equalizer was filled
with oxygen to the same tension that existed at the beginning of the
experiment.
Owing to the greatly increased carbon-dioxide production during
severe muscular work, the ventilating current was so adjusted that
the ventilating pump would cause 80 to 90 liters of air to pass by the
mouth of the subject per minute, thus minimizing the danger of the
rebreathing of the air. Furthermore, by means of the supplementary
valve M (see fig. 2, page 34), the dead space in the rubber tube leading
from the mouthpiece to the main air-pipe was wholly eliminated, for
when the valve N had been turned after the beginning of the experi-
ment, all of the air passed immediately by the mouthpiece. While
this deflection of the air-current was unnecessary in the experiments
with the subject standing, nevertheless it was also used in these experi-
ments in order that the procedure might be the same in both series.
Since it is important to note whether or not the subject remained in
essentially the same degree of muscular repose throughout the standing
experiments, a graphic record was obtained of the degree of movement
by connecting the subject with a cord attached to a movable pointer
traveling over a smoked-paper kymograph. In an ideal experiment
the course of the pointer would be a straight line. While it was impos-
sible for the subject to remain as perfectly quiet as he would when lying
upon a comfortable couch, nevertheless the regularity and constancy
of the muscular repose of the subject from experiment to experiment
was, to say the least, very striking. We are therefore safe in assuming
that in practically no experiment were the irregularities in the metabo-
lism for the standing position attributable to changes in the degree
of muscular repose of the individual, except in those tests in which
special positions while standing were assumed, such as the position of
"attention."
SITTING EXPERIMENTS.
A few sitting experiments were also made with one of the subjects.
These were not used as a base-line, but are recorded simply to show that
an endeavor was made to secure the best possible base-line for deduc-
tion from the total metabolism obtained during walking. The incre-
ment in the metabolism for the sitting position was unfortunately not
studied with sufficient sharpness to make a definite conclusion possible.
46 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
WALKING AND RUNNING EXPERIMENTS.
In the walking and running experiments the routine was essentially
that previously outlined for the standing experiments, save that during
the entire period and for several minutes before the experiment began
the subject was walking upon an electrically driven treadmill which
was kept in motion at a definite rate of speed. These rates of speed
varied from 53 meters per minute to 149 meters per minute. The
flexibility of the mouthpiece and its attendant by-pass made it possible
for the subject to walk with perfect comfort at these varying speeds and
the vertical movement of the body with each step did not interfere in
the slightest with the correct measurement of the gaseous exchange.
With a slow speed, there was no noticeable extraneous muscular effort
other than that of walking; with a high speed the subject made vig-
orous lateral motions of the arms, as is quite common with profes-
sional pedestrians when walking at high speed. As previously noted,
an attempt was made to measure the influence of this lateral motion by
studying the metabolism with the subject standing and swinging the
arms. In a number of the experiments the subject ran, although the
rate of progression was but little higher than in the experiments with
fast walking.
EXPERIMENTS WITH FOOD.
A considerable number of experiments were made after a breakfast
selected by the subject; a few were also made after dinner, the diet being
uncontrolled. In the experiments in which a study was made of the
possible influence of diets containing a preponderance of protein, fat, or
carbohydrate, the first meal of the day was given to the subject at the
Laboratory after a walking experiment in the forenoon in which he
was in the post-absorptive state. This meal consisted of steak, rice,
potatoes, or various fats. A second walking experiment was then made
under otherwise identical conditions. The exact weight of food was
not recorded, since our only aim was to make sure that the body was
plentifully supplied with the special food constituent being studied.
In general, the subject ate all that he possibly could and as a con-
sequence was frequently disinclined to walk in the afternoon.
A careful study of the effect of muscular work upon the urine was
impracticable, hence no analyses of the urine accompany these observa-
tions. Previous tests with one of the subjects have shown, however,
that the accomplishment of a large amount of severe muscular work was
not accompanied by an excessive excretion of nitrogenous products in
the urine.1
'Benedict and Cathcart, Carnegie Inst. Wash. Pub. 187, 1913, p. 98.
SUBJECTS. 47
SUBJECTS.
In this series of observations two subjects were used, both of whom
were more or less trained to severe muscular activity, as one (A. J. O.)
was a semi-professional baseball player and the other (M. A. M.) a
professional bicyclist. The preliminary observations in this research
were carried out by Dr. Carl Tigerstedt with the subject A. J. O. (sub-
ject I), a man of athletic build, who readily adapted himself to the
observations on the treadmill and with the respiration apparatus. He
was 29 years of age, 180 cm. in height, and had a body-weight with
clothing varying from 72.1 kilograms to 74.8 kilograms and without
clothing of 69.7 kilograms. Since in this study one of the prime objects
was to note the energy required to move 1 kilogram of material in the
forward direction 1 meter, i. e., 1 horizontal kilogrammeter, the body-
weight with clothing is of importance in each experiment. These
weights are given in detail in table 13 (page 78).
The major portion of the research was devoted to a study of forward
progression at varying speeds with the subject M. A. M., who had
previously served as the subject of Cathcart in the study of the mus-
cular work of bicycle-riding. This subject, who in this publication is
designated as subject II,1 was 31 years of age, 177 cm. in height, and
had a body-weight with clothing varying from 69.9 to 72.4 kilograms.
The average body-weight without clothing during this series of experi-
ments was 68.3 kilograms. The body-weight with clothing is given for
each experiment in tables 14 and 16 (pages 83 and 88).
'Further data regarding the body measurements, etc., of this subject may be found in the report
of the previous study on muscular work. See Benedict and Cathcart, Carnegie Inst. Wash. Pub.
187, 1913, p. 35.
48
ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
STATISTICS OF EXPERIMENTS.
The data regarding the experimental conditions, the respiratory
exchange, and the mechanics of walking for the experiments with sub-
ject I (A. J. O.) are given in table 3; the data for subject II (M. A. M.)
appear in table 4.
TABLE 3. — Summary of results obtained with subject I in experiments without food, during the
period from Nov. 26, 1913, to Dec. 27, 1913.
[Observations made by Dr. Carl Tigerstedt. Values per minute.]
Date and condition.
Dura-
tion.
Car-
bon
diox-
ide.
Oxy-
gen.
Respi-
ratory
quo-
tient.
Aver-
age
pulse-
rate.
Average
respi-
ration-
rate.
Dis-
tance.
Rais-
ing of
body.
Nov. 26.1
Standing,2 10h 10m a. m. . .
min. sec.
15 17
c.c.
283
c.c.
343
0.82
meters.
meters.
Standing,2 10h 45m a. m. . .
15 45
278
321
.86
18.3
Food about 1 p. m.
Standing, 2h 25m p.m....
15 04
277
341
.81
80
18.0
Standing, 2h 45m p. m ....
15 35
268
328
.82
87
18.4
Walking,3 3h 24m p. m
Nov. 28.
Standing, 10h 29m a. m . . .
15 15
15 07
943
226
1015
284
.93
.80
85
27.9
16.3
75.3
3.57
Standing, llh 03m a. m . . .
15 06
222
291
.76
96
17.2
Standing, llh 30m a. m . . .
15 48
218
279
.78
95
17.7
Nov. 29.
Standing, 9h 16m a. m . . . .
15 18
228
282
.81
91
18.6
Standing, 9h 50m a. m ....
15 19
219
282
.78
94
18.3
Walking,3 10h 22m a. m . . .
Dec 1.
Standing, 9h 30m a. m ....
15 02
15 11
886
222
873
276
1.02
.81
90
25.7
19.0
75.1
3.15
Standing, 9h 57m a. m ....
15 12
217
282
.77
94
19.5
Walking,3 10h 51m a. m. . .
Walking,3 Ilh34ma. m. . .
Dec. 2.
Standing, 8h 54m a. m ....
9 59
9 57
15 28
692
731
234
852
904
290
.81
.81
.81
88
25.4
24.5
19.4
76.0
76.6
3.26
3.36
Standing, 9h 17m a. m ....
15 22
223
289
.77
90
21.1
....
Standing, 10h 15m a. m. . .
15 25
214
280
.77
88
21.5
Walking,3 10h 30m a. m. . .
Walking,3 llh 18m a. m. . .
Dec. 8.
Standing, 9h 10m a. m ....
4 44
10 16
15 07
630
695
226
853
849
286
.74
.82
.79
90
26.8
25.3
19.5
76.2
76.8
3.20
4.62
Standing, 9h 38m a. m
15 07
214
269
.80
99
21.8
Standing, 10h 06m a. m . . .
15 05
209
270
.78
97
21.9
Walking,3 10h 45m a. m . . .
Walking,3 Ilh05ma. m. . .
Walking,3 llh 35m a. m. . .
Standing, llh 56m a. m . . .
10 47
10 17
10 17
13 55
685
701
697
215
845
842
872
270
.81
.83
.80
.80
85
27.3
26.7
25.5
23 0
76.5
77.2
77.5
3.57
3.62
3.68
Standing, 12h 20mp. m. . .
15 09
206
267
.77
89
23 0
'The subject had breakfast at about 7 a. m.
throughout this summary of results, the designation "standing" signifies standing in a
relaxed position unless otherwise specified.
3Subject I walked at a rate of not far from 105 steps per minute throughout the walking series,
except on December 22, 23, and 27. The total distance during the period on Nov. 26 was 1,148
meters; on Nov. 29, 1,129 meters; during the periods on Dec. 1, 1,520 meters; Dec. 2, 1,149
meters; Dec. 3, 2,415 meters. The subject did not walk between periods.
STATISTICS OF EXPERIMENTS.
49
TABLE 3. — Summary of results obtained with subject I in experiments without food, during the
period from Nov. 26, 1913, to Dec. 27, 1913 — Continued.
[Observations made by Dr. Carl Tigerstedt. Values per minute.]
Date and condition.
Dura-
tion.
Car-
bon
diox-
ide.
Oxy-
gen.
Respi-
ratory
quo-
tient.
Aver-
age
pulse-
rate.
Average
respi-
ration-
rate.
Dis-
tance.
Rais-
ing of
body.
Dec. 4.
Standing, 9h 12m a. m . . . .
win. sec
15 02
c.c.
220
c.c.
267
0.82
86
22.5
meters
meters.
Standing, 9h 21m a. m . . . .
15 10
208
269
.77
97
22.8
Standing, 10h 04m a. m . . .
15 10
213
265
.80
88
22.4
Walking,1 10h 35m a. m. . .
Walking,1 Ilh30ma. m. . .
Walking,1 12h 03m p. m . . .
Dec. 5.
Standing, 9h 18m a. m . . .
10 19
10 04
10 06
16 03
690
695
703
239
874
882
857
335
.79
.79
.82
71
100
24.9
26.4
25.2
21.8
77.7
77.7
78.2
3.41
3.68
3.57
Standing, 9h 48m a. m ....
15 08
240
340
.71
110
23.6
Standing, 10h 18m a. m . . .
15 07
230
328
.70
105
24.3
Walking,1 10h 52m a. m . . .
Walking,1 llh 12m a. m . . .
Walking,1 Ilh37ma. m. . .
Dec. 8.
Standing, 9h 17m a.m....
10 03
10 06
10 05
15 01
720
790
761
205
928
925
983
272
.78
.85
.77
.75
89
26.9
27.5
29.9
20.3
75.7
78.2
79.0
3.57
4.10
4.10
Standing, 9h 42m a. m ....
15 06
209
270
.77
91
20.9
Standing, 10h llm a. m. .
15 09
205
271
.76
93
22 4
Walking,2 10h 46m a. m . . .
Walking,2 llh 15m a. m. . .
Walking,2 Ilh41ma. m. . .
Walking,2 12h 07m p. m. . .
Dec. 9?
Standing, 9 a. m
11 57
11 59
12 04
11 54
15 06
692
729
721
722
255
829
889
887
920
357
.84
.82
.81
.78
.71
120
24.7
24.8
23.9
27.2
22.6
76.5
78.6
79.3
79.7
3.52
3.78
4.04
4.15
Standing, 9h 39m a. m ....
15 10
248
345
.72
110
22.8
Standing, 10h 25m a. m . . .
15 35
242
320
.76
105
23.2
Walking,2 Ilh07ma. m. . .
Walking,2 Ilh33ma. m. . .
Walking,2 12h llmp. m. . .
Dec. 15.
Standing, 9h 06m a. m ....
13 54
14 00
14 03
15 OS
792
782
753
233
952
899
891
279
.83
.87
.85
.83
89
23.6
26.9
27.0
21.6
76.0
78.3
79.1
3.68
3.89
4.04
Standing, 9h 37m a. m ....
15 17
212
268
.79
91
22.3
Standing, 10h 04™ a. m .
15 12
220
278
.79
88
22 8
Walking,2 10h 32m a. m . . .
Walking,2 10h 58m a. m . . .
Walking,2 Ilh25ma. m. . .
Walking,2 llh 50m a. m
15 02
15 05
15 02
17 18
808
757
734
727
980
891
875
.82
.85
.84
23.0
26.4
26.2
28 3
74.2
75.6
76.3
76 3
3.68
3.83
3.94
3 99
Dec. 16.
Standing, 9h 17m a. m ....
20 07
220
290
.76
103
21.8
Standing, 9h 48m a. m ....
20 12
221
284
.78
100
22.3
Standing, 10h 17m a. m . . .
20 10
229
283
.81
99
22.4
Walking,2 llh 05m a. m . . .
Walking,2 Ilh37ma. m. . .
Walking,2 12h 19m p. m . . .
20 06
20 00
20 08
758
754
721
882
853
793
.86
.88
.91
23.5
26.2
28.1
75.1
76.7
77.6
3.89
3.99
4.20
Subject I walked at a rate of not far from 105 steps per minute throughout the walking series,
except on December 22, 23, and 27. The total distance walked during the periods on Dec. 4
was 2,374 meters; Dec. 5, 4,303 meters. The subject did not walk between periods.
2The total distance walked on Dec. 8 was 7,363 meters; on Dec. 9, 6,114 meters; Dec. 15, 7,219
meters; Dec. 16, 7,247 meters. The subject walked between periods.
3Previous to the experiment of Dec. 9 the subject took an egg-phosphate.
50
ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
TABLES. — Summary of results obtained with subject I in experiments without food, during the
period from Nov. 26, 1913, to Dec. 27, 1913— Concluded.
[Observations made by Dr. Carl Tigerstedt. Values per minute.]
Date and condition.
Dura-
tion.
Car-
bon
diox-
ide.
Oxy-
gen.
Respi-
ratory
quo-
tient.
Aver-
age
pulse-
rate.
Average
respi-
ration-
rate.
Dis-
tance.
Rais-
ing of
body.
Dec. 17.
min. sec.
c.c.
c.c.
meters.
meters.
Standing, 8h 57m a. m ....
25 00
230
277
0.83
89
20.5
Standing, 9h 32m a. m ....
25 07
221
270
.82
92
21 A
Standing, 10h 07m a. m . . .
25 07
217
266
.82
93
22.1
Walking,1 10h 44m a. m. . .
20 09
695
823
.84
25.3
75.0
3.73
Walking,1 llh 14m a. m. . .
20 07
708
851
.83
. .
24.9
76.4
3.89
Walking,1 Ilh45ma. m. . .
20 16
706
872
.81
26.5
78.1
4.15
Walking,1 12h 18m p. m . . .
20 08
719
905
.79
26.5
78.6
4.15
Dec. 18.
Standing, 9h 03m a. m ....
25 05
238
272
.88
88
21.1
Standing, 9h 54m a. m ....
25 33
230
263
.87
88
21.3
Standing, 10h 34m a. m . . .
•
25 13
220
255
.86
83
21.6
Walking,1 Ilh08ma. m. . .
20 04
726
811
.89
23.9
75.3
3.52
Walking,1 Ilh40ma. m. . .
20 28
740
833
.89
25.2
76.4
3.68
Walking,1 12h 10m p. m . . .
20 04
730
864
.84
27.7
76.7
3.68
Walking,1 12h 39m p. m . . .
20 12
734
867
.85
27.3
76.9
3.73
Dec. 19.
Standing, 9h 43m a. m ....
25 03
238
279
.85
96
22.5
Standing, 10h 16m a. m . . .
25 06
239
282
.85
97
23.3
Standing, 10h 49m a. m . . .
25 06
241
275
.88
100
23.1
Walking,1 llh 25m a. m. . .
20 06
789
869
.91
23.9
76.1
3.83
Walking,1 llh 54m a. m. . .
20 06
772
860
.90
28.1
77.9
3.99
Walking,1 12h 21m p. m. . .
20 10
755
871
.87
29.0
78.3
4.10
Walking,1 12h 52m p. m. ..
10 40
759
872
.87
29.8
78.7
4.20
Dec. 20.
Standing, 8h 55m a. m ....
25 06
237
272
.87
99
23.3
Standing, 9h 29m a. m ....
25 17
271
106
22.5
Standing, 10h 06m a. m . . .
25 10
224
273
.82
106
23.2
Standing, llh 10m a. m . . .
24 56
216
263
.82
100
22.5
Walking,1 Ilh44ma. m. . .
20 04
690
825
.84
26.1
76.2
3.68
Walking,1 12hllmp. m. . .
20 07
735
884
.83
28.5
77.7
4.04
Walking,1 12h 40m p. m. . .
20 02
731
924
.79
30.1
78.6
4.20
Walking,1 lh 02m p. m
19 59
747
934
.80
31.3
78.9
4.25
Dec. 22.
Walking,1 10h 17m a. m. . .
20 15
718
873
.82
27.4
76.3
4.07
Walking,1 10h 47m a. m. . .
20 06
610
790
.77
28.6
65.9
3.17
Walking,1 llh 20m a. m. . .
20 07
641
901
.71
30.2
77.4
4.28
Walking,1 Ilh48ma. m. . .
20 06
600
788
.76
29.7
67.5
3.41
Dec. 23.
Walking,1 9h 25m a. m ....
20 29
695
833
.83
. .
25.7
75.9
3.97
Walking,1 9h 59m a. m ....
20 47
589
740
.80
. .
24.2
66.4
3.07
Walking,1 10h 38m a. m. . .
20 18
694
863
.80
. .
27.2
76.9
4.08
Walking,1 Ilh12ma. m. . .
20 06
602
764
.79
26.0
66.4
3.30
Dec. 27.
Walking,1 9h 56m a. m
21 53
685
846
.81
27.0
78.4
4.06
Walking,1 10h 41m a. m. . .
20 43
563
725
.78
26.9
65.2
3.02
Walking,1 llh 15m a. m. . .
20 52
664
852
.78
28.6
78.6
4.13
Walking,1 Ilh48ma. m. . .
20 11
560
732
.76
29.1
65.1
3.02
Subject I walked at a rate of not far from 105 steps per minute throughout the walking series
except on Dec. 22, 23, and 27. The total distance walked on Dec. 17 was 8,798 meters; Dec. 18,
8,435 meters; Dec. 19, 7,581 meters; Dec. 20, 8,142 meters; Dec. 22, 10,075 meters; Dec. 23,
10,338 meters; Dec. 27, 11,908 meters. The subject walked between periods. The steps per
minute in the last three periods on Dec. 22 were 95, 101, and 95; during the periods on Dec. 23,
105, 94, 103, and 96; on Dec. 27, 106, 94, 103, and 92, respectively.
STATISTICS OF EXPERIMENTS.
51
TABLE 4. — Summary of results in experiments with subject II, during the period from
Mar. 16, 1914, to May 15, 1914.
[Values per minute.]
Date, condition, and time.
Dura-
tion.
Car-
bon
diox
ide.
Oxy
gen.
Respiratory
quotient.
o> .
MS
2?
« £
>3
*4 o
:**
c3 •** !-,
t, a 1
"El
•<
Dis-
tance
Steps
Rais-
ing
of
body.
Mar. 16.
Food, 7h 40m a. m. :
Sitting,1 9h 38m a. m
min. sec
21 26
c.c.
218
c.c.
281
0.77
18 7
meters
meters.
Sitting,1 10h 26m a. m
23 44
203
256
.79
18 3
Standing,2 llh 22m a. m
20 13
217
274
.79
18 7
Standing,2 llh 56m a. m. .
20 14
223
286
.78
20 2
Walking,3 12h 53m p. m .
19 45
672
810
83
26 4
74 3
107
2 88
Food, Ih45m p. m.:
Sitting, 3h 05m p. m
21 28
250
304
.82
19 9
Standing, 3h 52m p. m
18 29
261
319
.82
22 1
Walking,3 4h 30m p. m . . . .
21 27
721
815
88
29 2
75 3
97
3 17
Mar. 17.
Food, 12 noon:
Sitting, 3h 45m p. m
18 36
213
272
.78
18 1
Mar. 18.
Food, 7h 30m a. m. :
Sitting, 9h 08m a. m
20 51
233
286
.82
19 2
Standing, 10 a. m
18 25
244
293
.83
18 2
Walking,4 10h 55m a. m
18 39
699
840
.83
25 1
76 0
98
3 34
Walking,4 llh 35m a. m. . . .
19 19
702
27 0
78 0
105
3 62
Food, 12h 30m p. m.:
Sitting, 3h 09m p. m
21 5
248
297
.84
19 3
Walking,4 3h 54m p. m
Mar. 19.
Food, 7h 30m a. m. :
Sitting, 9h 24m a. m
20 57
18 49
758
242
808
282
.94
.86
67
26.9
18 7
76.3
99
3.75
Standing, 10h 37m a. m
17 29
231
295
.78
75
19.3
Walking,5 1 lh 21m a. m
20 31
720
870
.83
26 9
74 9
99
3 16
Food, 12h 30mp. m.:
Sitting, 2h 18m p. m
18 21
259
322
.80
77
21 0
Standing, 3h 05m p. m
17 5
247
303
.82
86
20 7
Walking,5 3h 50m p. m . . .
18 11
739
833
89
28 1
74 9
96
3 55
Mar. 20.
Without food:
Standing,6 9h 58m a. m
18 48
218
275
.79
71
16 8
Walking,7 10h 51m a. m
17 52
583
725
.80
20 4
92
2 61
Food, 12h 30m p. m.:
Standing,8 3h 56m p. m
16 28
274
318
.86
87
20.3
Walking,7 4h 34m p. m
19 32
602
634
95
22 6
52 7
92
2 3Q
Curing "sitting" periods in this summary the subject sat comfortably in a chair and was as
quiet as possible.
2The designation "standing" signifies standing in a relaxed position unless otherwise specified.
The subject stood as quietly as possible.
3Total distance preliminary to and during period before lunch, 1,633 meters; after lunch,
1,740 meters.
4Total distance before lunch, 4,573 meters, the walking being continuous; after lunch, distance
preliminary to and during period, 1,690 meters.
5Total distance preliminary to and during period before lunch, 1,573 meters; after lunch,
1,462 meters.
6Standing on one leg, right leg relaxed, with hands in pockets. Subject found this more tiring
than standing on both legs.
7Total distance preliminary to and during period before lunch, about 1,057 meters; after lunch
the distance was 1,055 meters. The subject's hands swung loosely at his side as he walked. It
should be stated that this was the case except as otherwise indicated.
8Standing on both legs with hands in pockets.
52
ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
TABLE 4. — Summary of results in experiments with subject II, during the period from
Mar. 16, 1914, to May 15, 191 4~ Continued.
[Values per minute.]
Date, condition, and time.
Dura-
tion.
Car-
bon
diox-
ide.
Oxy-
gen.
Respiratory
quotient.
Average
pulse-rate.
Average
respira-
tion-rate.
Dis-
tance.
Steps.
Rais-
ing
of
body.
Mar. 21.
Food, 7h30raa. m.:
Standing,1 9h 15m a. m
min. sec.
19 27
c.c.
271
c.c.
338
0.80
98
20 7
meters.
meters.
Standing, attention,2 10h 09m
a. m
16 58
249
288
.87
91
21 2
Walking 3 llh 15m a. m
22 2
675
764
.88
22 3
57 9
104
3 11
Food, 12h30mp. m.:
Standing,1 2h 09m p. m
15 44
275
355
.78
96
20 9
Standing, attention,2 2h 48m p.m.
15 5
270
295
.92
94
22 6
Walking,3 3h 32m p. m
20 18
593
699
.85
23 9
52 8
92
2 59
Mar. 23.
Food, 7 a. m.:
Standing, staff,4 9h 50m a. m . . .
16 15
282
333
.84
74
20 5
Walking,5 10h 37™ a. m
19 19
625
689
.91
22 8
57 9
93
2 74
Walking,5 llh 34m a. m .
18 36
670
764
.88
25 2
57 5
99
2 61
Mar. 24.
Without food :
Standing, staff, 9h 07m a. m ....
18 23
217
250
.87
8?
18 8
Standing, support,6 9h 54m a. m.
19 6
196
256
.77
79
17 7
Walking,7 llh 05m a. m
16 13
628
778
.81
21 9
60 6
95
1 09
Food, 12h 15mp. m.:
Standing, staff, lh 56m p. m
16 49
289
356
.81
95
22 1
Standing, support,6 2h 40m p. m.
17 51
254
301
.84
9?
20 7
Walking 7 3h 34m p. m
16 1
734
809
.91
21 3
62 7
101
81
Mar. 25.
Without food:
Sitting, 9h 58m a. m
18 5
192
260
.74
59
18 0
Standing, attention,8 10h 57m
a. m .
14 11
206
265
.78
79
18 7
Walking,9 llh 52m a. m
17 3
570
709
.80
19 8
60 6
92
1.77
Food, 12h30mp. m.:
Sitting 2h 03m p. m
15 15
272
316
.86
73
19 6
Standin" attention 8 2h 38m p m.
13 53
292
309
95
95
20 2
Walking,9 3h 39m p. m . . .
17 33
704
726
.97
24.1
61.1
90
1.50
'Standing with weight on one leg, the other leg relaxed; hands in pockets.
2Standing on both legs, with hands at sides, in tense position; subject stiff and tired after the
period was finished.
3Total distance before lunch, 1,362 meters; after lunch, 1,113 meters.
4Standing relaxed, leaning on long staff, with one hand above the other on the staff.
6Total distance, 2,568 meters, the walking being continuous. During the first of the two periods
subject's hands were upon a support at either side; in the second period his hands were swinging
at his sides.
6Leaning against support. In the morning subject stood with hands in his pockets and was not
sufficiently comfortable; in the afternoon he placed his hands on his back.
'Total distance before lunch, 1,150 meters; after lunch, 1,190 meters. In the first period on
this day a counter was first used to obtain the number of steps and a wheel for measuring the total
height of the raising of the body. Both these devices were generally in use during the remainder
of the series.
'Subject could not wholly secure the erect position desired; at the end of the afternoon period
he was not able to stand longer.
9Total distance before lunch, 1,189 meters; after lunch, 1,295 meters. In both periods, the
subject supported his hands on his legs.
STATISTICS OF EXPERIMENTS.
53
TABLE 4. — Summary of results in experiments with, subject II, during the period from
Mar. 16, 1914, to May 15, 1914— Continued.
[Values per minute.)
Date, condition, and time.
Dura-
tion.
Car-
bon
diox-
ide.
Oxy-
gen.
Respiratory
quotient.
o> .
M.£
03 2
t* i
« %
>~3
^ a
Average
respira-
tion-rate.
Dis-
tance.
Steps.
Rais-
ing
of
body.
Mar. 26.
Without food:
Standin^ staff, 9h 10m a. m ....
min. sec.
17 15
c.c.
223
c.c.
253
0.88
so
18.7
meters.
meters.
Standing support l 9h 49™ a. m .
18 18
201
238
.84
79
19.1
Walkin"- 2 10h 58m a. m.
17 49
605
701
.86
22 0
62.7
99
3 09
Food, 12h30mp. m.:
Standing staff 2 p m
15 53
274
317
.86
94
20 6
Standing support 2h 38m p m
16 11
254
289
.88
93
21 8
Walking 2 3h 35m p. m
18 35
694
738
.94
25.4
60.7
96
2 30
Mar. 27.
Without food:
Sitting, 9h 18m a. m
12 32
195
234
.83
58
17.6
Standing, attention, 10h 03m
a m
15 5
219
272
.80
71
18.9
Walking 3 llh 56m a. m
18 8
544
652
.83
22 8
57.6
95
2 09
Food, 12h45mp. m.:
Standing, attention, 2h 24m p.m .
15 14
294
298
.99
95
22.4
Walking 3 2h 57m p. m
18 25
681
727
.94
27.1
58.6
91
2.15
Mar. 28.
Food, 7h30ma. m.:
Standing support 9*1 40m a. m
13 43
279
304
.92
87
20 7
Standing, support, 10h 15m a. m .
17 43
246
276
.89
81
21.0
Walking,4 llh 30m a. m
16 16
654
702
.93
22.1
59.4
97
2.52
Food, 12h30mp. m.:
Standing support, I'1 44m p. m
16 48
280
314
.89
85
21 0
Walking,4 2h 24™ p. m
17 12
743
759
.98
24.5
59.3
96
2.12
Mar. 30.
Food, 7h 30m a. m. :
Standing, attention, 9h 36m a. m .
15 54
261
271
.96
76
20.2
Standing staff, 10h 15m a. m . . .
14 51
261
296
.88
71
18.9
Walking 8 llh 17m a. m
17 15
658
744
.88
19 2
58 5
100
2 26
Food, 12h45mp. m.:
Standing staff lh 50m p. m
15 8
318
339
94
95
21 3
Walking,5 2h 27m p. m
16 56
681
722
.94
24.8
58.5
92
2.40
Walking B 3h 26m p. m .
15 11
666
709
.94
21.9
57.3
99
2.24
Mar. 31.
Without food:
Standing support, 8h 38m a. m
17 48
214
239
89
77
18 4
Standing relaxed 9h 21m a. m.
16 40
209
260
80
71
17 8
Standing, attention, 10h 02m
am
13 9
233
272
.86
75
19.4
Walking 6 llh 47m a. m
15 59
571
673
.85
21 6
57.2
98
2 01
lLeaning comfortably against support, hands on back.
2Total distance before lunch, 1,286 meters; after lunch, 1,345 meters. Subject held his hands
on his legs as he walked.
3Total distance before lunch, 1,184 meters; after lunch, 1,266 meters. Subject held his hands
at his sides as he walked.
4Total distance before lunch, 1,158 meters; after lunch, 1,210 meters. In the morning, subject
walked with hands held on his legs; in the afternoon his hands were swinging at his sides.
BTotal distance before lunch, 1,198 meters, subject walking with hands swinging. After lunch
distance was 2,229 meters, hands being on support in the first period and swinging at his sides in
the second period. Most of the time between periods he was not walking.
6Total distance before lunch, 1,085 meters; after lunch, 1,020 meters.
54
ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
TABLE 4. — Summary of results in experiments with subject II, during the period from
Mar. 16, 1914, to May 15, 1914— Continued.
[Values per minute.]
Date, condition, and time.
Dura-
tion.
Car-
bon
diox-
ide.
Oxy-
gen.
Respiratory
quotient.
o
M.g
03 g
si
>3
<j a
Average
respira-
tion-rate.
Dis-
tance.
Steps.
Rais-
ing
of
body.
Mar. 31 — Continued.
Food, 1 p. m. :
Walking,1 2h 08m p. m
min. sec.
14 57
c.c.
685
c.c.
705
0 97
23 9
meters.
57 7
99
meters.
1 72
Standing, relaxed, 2h 55m p. m . .
15 36
277
345
.80
89
20 6
Standing, attention, 3h 40m p. m.
11 52
265
326
.81
89
20 7
Apr. 1.
Without food:
Standing, 9h 50m a. m
15 13
213
266
.80
75
17 9
Walking,2 llh 21m a. m
15 57
563
699
81
21 5
59 3
100
2 22
Food, 12 noon:
Standing, lh 42m p. m
16 30
283
319
.89
86
20 2
Apr. 2.
Food, 7h 15ma. m.:
Standing, support, 8h 44m a. m . .
15 30
273
306
.89
89
20 0
Standing, relaxed, 9h 53m a. m . .
12 15
253
281
.90
86
19 7
Standing, attention, 10h 45m
a. m
12 18
248
268
.93
78
18 8
Apr. 3.
Without food:
Sitting, 8h 46m a. m
15 20
219
245
.89
67
19.4
Standing, staff, 9h 26m a. m ....
15 7
224
278
.81
77
19 1
Walking,3 10h 33m a. m
13 43
771
903
85
20 6
76 2
114
2 38
Food, 12h45mp. m.:
Walking,3 lh 28m p. m
14 18
667
686
97
23 4
57 0
100
2 02
Walking 3 2h 28m p. m
14 7
894
938
95
22 2
77 0
110
2 84
Walking,3 3h 35m p. m
14 52
860
895
.96
22 8
78 9
112
3 38
Standing, 4h 28m p. m
16 24
244
293
.83
81
22 0
Apr. 4.
Food, 7h 15ma. m.:
Walking,4 10h llm a. m
15 35
608
651
93
57Cj
20 7
55 1
100
1 91
Walking,4 10h 56m a. m
15 42
573
620
92
679
22 6
56 8
100
1 98
Walking,4 llh 29m a. m
14 18
554
669
.83
21 3
56 2
99
1 87
Food, lh 15mp. m.:
Walking,4 2 p. m
13 57
657
707
.93
23 3
54 4
101
2 05
Walking,4 2h 55m p. m . . . .
15 45
705
755
93
24 6
58 1
101
2 21
Apr. 66
Without food:
Standing, 9h 04m a. m .
16 9
218
246
89
574
19 8
Walking,7 9h 41m a. m
16 11
586
681
86
579
17 3
57 8
104
1 78
Walking,7 10h 22m a. m
15 41
567
668
85
574
20 9
56 8
105
1 83
Walking,7 llh 13m a, m
17 14
553
659
84
577
21 5
56 0
102
1.91
Protein, 12h 55m p. m.:
Standing, lh 24m p. m
13 16
241
296
82
19 2
Walking,7 lh 46m p. m
15 59
631
725
87
B78
19 4
57 5
105
2.21
Walking,7 2h 24m p. m
14 36
641
712
90
21 6
57 2
105
1.94
Walking,7 3h 05m p. m
15 49
617
70S
87
586
23 7
56 3
99
1.81
distance before lunch, 1,085 meters; after lunch, 1,020 meters.
2Total distance preliminary to and during period, 1,164 meters.
3Total distance before lunch, 1,244 meters; after lunch, 7,296 meters. During about 43 minutes
between the first two periods of the afternoon subject was not walking.
4Total distance before lunch, 5,207 meters; after lunch, 4,132 meters. The walking was
continuous.
'Electrocardiograms, were obtained during these periods by means of the string galvanometer.
6On and after Apr. 6, subject's food was prepared and eaten at the Laboratory.
7Total distance before lunch, 6,140 meters; after lunch, 5,433 meters. The walking, as was
usually the case in the days that follow, was continuous.
STATISTICS OF EXPERIMENTS.
55
TABLE 4. — Summary of results in experiments with subject II, during period from
Mar. 16, 1914, to May 15, 1914— Continued.
[Values per minute.]
Date, condition, and time.
Dura-
tion.
Car-
bon
diox-
ide.
Oxy-
gen.
Respiratory
quotient.
to .
M «
S3 g
M i
« £
>~5
«! ft
* ' 6
M£"£
c3 "* i*
K °- C
» S o
> i- V-
^
Dis-
tance.
Steps.
Rais-
ing
of
body.
Apr. 7.
Without food:
Standing, 9h IS™ a. m
min. sec.
14 29
c.c.
214
c.c.
257
0.83
28?i
19 2
meters.
meters.
Walking,1 9h 56m a. m
15 30
606
729
.83
275
20 1
59.6
109
1 98
Walking,1 10h 58m a. m
Standing llh 27m a. m
15 59
14 8
544
198
660
235
.82
.84
279
2PO
22.1
21 4
58.2
105
1.95
Protein, lh 03m p. m.:
Standing, lh 31m p. m
13 23
217
289
.75
288
19 6
Walking,1 2h 07m p. m
16 19
643
732
.88
281
20 4
58.8
107
1 78
Walking J 3 p. m . .
13 36
671
772
.87
288
25 1
58.7
107
1 83
Walking,1 3h 42m p. m
13 59
593
701
.85
24.5
56.9
99
1.82
Apr. 8.
Without food:
Standing, 9h 10m a. m
14 6
204
265
.77
18 4
Walking,3 9h 40m a. m
12 15
761
922
.82
21.0
76.1
121
3.01
Walking,3 10h 14m a. m
14 22
662
826
.80
23 0
77.6
117
2.81
Walking,3 llh Olm a. m .
13 29
660
807
.82
24 4
78.3
113
2 85
Protein, 1 p. m. :
Standing, lh 23m p. m
12 54
230
275
.83
19 1
Walking,3 2h Olm p. m
13 22
785
869
.90
22.6
76.9
120
2.50
Walking,3 2h 44m p. m
13 47
792
892
.89
25.7
78.0
117
3.01
Walking,3 3h 30m p. m
13 1
782
917
.85
25 6
79.2
118
2 70
Apr. 9.
Without food :
Standing, 8h 42ra a. m
14 21
202
228
.89
82
18.7
Walking,4 9h 22m a. m
15 15
590
701
.84
21.0
59.3
107
1 92
Walking,4 10h 07m a. m ....
14 23
546
663
.82
22 5
58.8
105
2 05
Walking,4 10h 47m a. m
14 34
568
697
.81
25 1
59 0
107
1 98
Carbohydrate, 1 p. m.:
Standing, lh 19ra p. m
12 42
245
295
.83
76
19.4
Walking,4 lh 45m p. m
15 32
649
704
.92
22.9
59.4
107
1.95
Walking,4 2h 26m p. m
13 48
646
691
.93
26.2
59.0
106
1 94
Walking,4 3h 14m p. m . ...
15 37
651
715
.91
26 1
58.8
104
1 94
Apr. 10.
Without food:
Standing 8h 54m a. m
13 39
212
257
.83
78
19 3
Walking,5 9h 34m a. m
14 22
795
814
.98
22.6
77.3
120
2.77
Walking,6 10h 57m a. m
12 46
712
841
.85
24.4
78.9
114
3.21
Carbohydrate, 12h 08m p. m.:
Standing, 12h 31™ p. m
13 13
264
301
.88
86
21 1
Walking 5 lh 16m p. m
13 23
879
948
.93
23 1
78 0
118
3 01
Walking 5 lh 50m p. m
14 31
857
926
.93
26 0
79 1
116
3 17
Walking,6 2h 30m p. m
14 25
823
881
.93
26.8
79.7
116
3.35
Apr. 14.
Without food :
Standing, 9b 02m a. m
15 52
223
245
.91
<H
19.0
Walking,6 9h 48m a. m
13 51
630
695
.91
20 7
61 7
104
2 45
Walking 6 10h 22m a. m
14 35
597
666
.90
23 6
62 1
103
2 34
Walking 6 1 lh 06m a. m
14 59
563
672
84
24 4
62 4
102
2 37
1Total distance before lunch, 5,007 meters; after lunch, 6,560 meters.
Electrocardiograms were obtained during these periods by means of the string galvanometer.
3Total distance before lunch, 7,287 meters; after lunch, 7,933 meters.
4Total distance before lunch, 5,868 meters; after lunch, 6,141 meters.
6Total distance before lunch, 8,372 meters; after lunch, 7,221 meters.
6Total distance before lunch, 6,157 meters; after lunch, 6,062 meters.
56
ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
TABLE 4. — Summary of results in experiments with subject II, during the period from
Mar. 16, 1914, to May 15, 1914— Continued.
[Values per minute.]
Date, condition, and time.
Dura-
tion.
Car-
bon
diox-
ide.
Oxy-
gen.
Respiratory
quotient.
eu .
MS
03 oj
st
>3
< a
* d <"
"S-5
03 •— •„
n a i
« £ §
>• (H '+»
<j
Dis-
tance.
Steps.
Rais-
ing
of
body.
Apr. 14 — Continued.
Carbohydrate, 1 p. m.:1
Standing lh 23m p m
ruin. sec.
14 32
c.c.
242
c.c.
295
0.82
QO
19 5
meters.
meters.
Walking 2 lh 59m p. m
14 15
681
674
1.01
23.4
61.2
102
2.38
Walking 2 2h 37m p m
15 36
672
711
.94
25.6
62 0
102
2.20
Walking,2 3h 15m p. m
14 16
671
693
97
25.9
62.2
104
2.27
Apr. 15.
Without food:
Standing 8h 48m a m
15 41
214
252
.85
74
17 7
Walking 3 9h 30m a. m
12 57
818
934
88
22.7
77.2
119
3.33
Walking 3 10h 08m a. m
15 19
696
829
.84
25.7
79.4
115
3.52
Walking 3 10h 53m a. m
14 21
690
837
.82
25.4
80.2
114
3.49
Carbohydrate, 12h 52m p. m.:
Standing lh 14m p m
14 1
267
277
.96
83
20.9
Walking 3 lh 52m p. m
14 40
875
902
97
26.4
78.2
117
3.88
Walking 3 2h 29m p. m
14 54
859
878
.98
28.9
80.1
115
3.72
Walking 3 3h 05m p. m ....
17 40
898
924
.97
28.9
80.6
117
3.88
Apr. 16.
Without food:
Standing 8h 32™ a m
14 55
258
QO
19.5
Walking,4 9h 14m a. m
15 22
568
644
88
21.0
61.9
105
2.38
Walking 4 9h 53m a. m
12 34
544
668
.81
24.4
62.3
106
2.37
Walking 4 10h 36m a. m . .
14 2
553
661
84
25.1
61.8
106
2.20
Fat, Ilh30ma. m.:
Standing 12h 03m p. m
14 10
239
292
.82
98
19.8
Walkin" 4 12h 44m p m
14 13
600
683
.88
23.4
61.6
107
2 49
Walking 4 lh 20m p m
15 31
593
635
.93
25.7
62.3
105
2 48
Walking,4 2h 14m p. m
15 53
611
701
87
26.2
62.2
105
2.24
Walking 4 3h 10m p. m
18 8
586
707
83
25.0
61.9
103
2.21
Apr. 17.
Without food:
Standing 8h 31m a. m
14 22
214
265
81
85
20.9
Walking 5 9h 08m a. m
13 48
773
895
.86
23.8
76.6
118
3 36
Walking 5 9h 50m a m
14 58
672
816
.82
24.6
78.1
117
3 45
Walking 8 10h 37m a m
14 39
693
862
.80
26.8
79.3
117
3 80
Fat, Ilh30m a. m.:
Standing 12h 09m p m
16 18
231
281
.82
QQ
20.5
Walking 5 12h 48m p. m
14 49
715
832
86
23.5
77.6
118
3.96
Walking 6 lh 34m p. m
13 20
735
883
83
26.8
79.5
117
3.78
Walking 5 2h 18m p. m
14 11
799
938
85
27.9
80.0
119
3.85
Walking 5 3h 17m p. m
16 15
721
856
.84
27.2
SO.O
115
3.67
Apr. 21.
Without food:
Standing 10h 25m a. m
13 59
205
242
.85
78
19.1
Walking 6 llh 16m a. m
15 50
562
639
. .88
22.8
60.8
105
2 32
Fat, 12h30mp. m.:
Standing lh 03m p. m
12 33
220
301
.73
91
19.7
Walkin" 6 lh 45m p. m
14 13
590
683
.86
21.8
60.4
104
2.45
Walkino- 6 2h 25m p. m
14 55
624
699
.89
25.2
60.6
104
2 56
Walking 6 3h 10m p. m
14 17
608
705
.86
25.8
60.5
103
2 34
Walking 6 4h Olm p. m
16 12
592
709
.83
25.4
60.5
105
2 23
JSubject did not eat so much as on other days.
2Total distance before lunch, 6,157 meters; after lunch, 6,062 meters.
3Total distance before lunch, 8,306 meters; after lunch, 7,657 meters.
4Total distance before lunch, 6,350 meters; after lunch, 10,547 meters.
5Total distance before lunch, 8,680 meters; after lunch, 13,566 meters.
6Total distance preliminary to and during period before lunch, 1,651 meters; after lunch,
9,494 meters.
STATISTICS OF EXPERIMENTS.
57
TABLE 4. — Summary of results in experiments with subject II, during period from
Mar. 16, 1914, to May 15, 1914— Continued.
[Values per minute. 1
Date, condition, and time.
Dura-
tion.
Car-
bon
diox-
ide.
Oxy-
gen.
Respiratory
quotient.
SI ,
M.2
03 rt
!H I
« £
>3
<4 a
0 d a>
S.SB
Ssg
> t~ -5
<
Dis-
tance.
Steps.
Rais-
ing
of
body.
Apr. 22.
Without food:
Standing, 8h 39m a. m
min. sec.
14 20
c.c.
207
c.c.
251
0.83
84
18.0
meters.
meters.
Walking,1 9h 27m a. m
15 17
687
804
85
23 5
76 8
118
3 33
Walking 1 10h 09m a. m
13 26
655
829
79
26 1
78 6
118
3 44
Walking,1 10h 44m a. m
13 48
647
822
.79
25 7
79 2
115
3 42
Fat, Ilh40ma. m.:
Standing, 12h 14m p. m
14 11
227
299
.76
Q3
20.8
Walking,1 12h 55m p. m .
14 30
725
833
87
26 0
77 3
116
3 86
Walking,1 lh 34m p. m
13 37
729
877
.83
28.7
78 7
118
3 86
Walking,1 2h 20m p. m
13 18
737
877
.84
28 4
79 5
118
3 92
Walking,1 3h Olm p. m
14 03
739
858
86
28 4
79 7
116
3 84
Apr. 23.
Without food :
Standing, 8h 40m a. m
15 57
208
252
.82
74
19 3
Walking,2 9h 34m a. m ....
15 23
561
675
83
20 5
61 1
105
2 53
Walking,2 10h 15m a. m
16 37
528
660
80
24 2
105
2 46
Protein, llh 10m a. m.:
Standing, llh 40m a. m
14 7
223
254
.88
81
20.1
Walking,2 12h 24m p. m
13 0
644
722
.89
19 7
61 2
106
2 74
Walking,2 lh 03m p. m
13 18
607
705
86
24 6
61 6
105
2 57
Walking,2 lh 47m p. m
13 56
606
707
86
25 0
61 6
104
2 48
Walking,2 2h 28m p. m
15 5
605
707
86
24 3
61 7
103
2 63
Apr. 24.
Without food :
Standing, 9h 14m a. m
12 43
198
8?
18.7
Walking,3 9h 55m a. m .
14 31
635
790
80
21 4
76 4
116
3 60
Walking,3 10h 26m a. m
12 24
636
828
77
25 8
78 4
117
3 69
Protein, llh 15m a. m.:
Standing, llh 58m a. m
14 19
219
299
.73
94
20 3
Walking,3 12h 35m p. m
14 21
699
835
.84
22 9
77 0
114
3 74
Walking,3 lh 07m p. m . .
13 9
695
853
81
26 3
78 8
115
3 88
Walking,3 lh 42m p. m
13 54
704
890
79
26 3
80 0
115
3 84
Walking,3 2h 15m p. m
14 0
712
880
81
25 4
80 0
115
3 88
Apr. 25.
Without food:
Standing, 9h 30m a. m
12 59
192
264
.73
79
19.6
Walking,4 10 a. m
13 24
543
665
82
20 2
63 0
105
2 65
Walking4 10h 33m a. m
13 25
531
695
76
23 3
64 0
107
2 69
Carbohydrate, llh 20m a. m.:
Standing, llh 49m a. m
12 21
274
324
.85
83
20 6
Walking,4 12h 25m p. m
14 37
668
708
.94
22 2
63 1
104
2 88
Walking,4 12h 56m p. m
17 17
662
711
.93
24 4
63 8
105
2 70
Walking,4 lh 40m p. m
15 23
688
694
99
25 7
63 7
106
2 85
Walking,4 2h 30m p. m
15 13
641
669
96
25 2
63 3
104
2 64
distance before lunch, 7,548 meters; after lunch, 11,466 meters.
2Total distance before lunch, about 4,300 meters; after lunch, 8,908 meters.
3Total distance before lunch, 3,888 meters; after lunch, 9,414 meters.
4Total distance before lunch, 3,216 meters; after lunch, 9,089 meters.
58
ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
TABLE 4. — Summary of results in experiments with subject II, during period from
Mar. 16, 1914, to May 15, 1914 — Continued.
[Values per minute.)
Date, condition, and time.
Dura-
tion.
Car-
bon
diox-
ide.
Oxy-
gen.
Respiratory
quotient.
<D .
M.S
03 g
£ &
>~3
•< Q
Average
respira-
tion-rate.
Dis-
tance.
Steps.
Rais-
ing
of
body.
Apr. 27.
Without food:
Standing 9h 10m a. m
min. sec.
13 52
c.c.
217
c.c.
245
0.89
77
20 5
meters.
meters.
Walking,1 9h 48m a. m
13 54
681
767
.89
23.3
73.5
115
3.25
Walking,1 10h 20m a. m
12 26
679
821
.83
26.5
78.1
116
3.64
Carbohydrate, llh 10™ a. m.:
Standing, llh 34m a. m
13 50
294
326
.90
75
21.0
Walking,1 12h 12m p. m
14 22
845
854
.99
24.7
77.5
116
3.60
Walking l 12h 45m p. m
13 29
837
797
1.05
27.5
78.9
115
3 56
Walking,1 lh 21m p. m
15 43
886
840
1.05
28 6
79.8
116
3 88
Walking,1 2h 08m p. m
15 32
850
801
1.06
27.6
80.2
116
3.74
Apr. 28.
Without food :
Standing 8h 39m a m
12 30
221
274
.81
8?
19 6
Walking 2 9h 12m a. m
15 53
713
828
.86
23.0
78.2
118
3.41
Walking,2 9h 48m a. m
13 4
699
820
.85
26.4
79.8
116
3.60
Walking 2 10h 26m a m
13 20
680
846
.80
26.1
80.0
116
3 53
Walkin" - llh 07m a m
13 52
689
858
.80
26.5
80 7
118
3 80
Walking,2 llh 51m a. rn
15 20
716
925
.77
27.4
80.4
121
3.33
Walking,2 12h 33m p. m .
14 44
657
854
.77
27.2
80.2
116
3.67
Walking,2 lh 06ra p. m
14 43
682
865
.79
28.1
80.2
119
3.80
Walking,2 lh 49m p m
15 8
659
859
.77
27.8
80.4
116
3.46
Apr. 29.
Carbohydrate, 8h 35m a. m. :
Walking 3 9h 08m a m
14 8
817
864
.95
27.1
76.9
114
3.63
Walking,3 9h 45m a. m
14 26
789
863
.91
27.2
78.2
114
3.56
Walking,3 10h 24m a. m
14 11
817
839
.97
27.8
79.5
114
3.52
Walking,3 llh 04m a. m . .
14 42
797
810
.98
26.9
80.9
117
3.74
Walking,3 llh 40m a. m
14 25
777
823
.94
26.6
81.1
116
3.76
Walking,3 12h 18m p. m
13 42
696
790
.88
27.2
80.9
115
3.29
Walking 3 12h 58m p. m
14 56
704
848
.83
26.9
81.0
120
3.73
Walking,3 lh 35m p. m
15 19
666
830
.80
27.1
81.1
116
3.69
May 4.
Without food :
Walking,4 9h 27m a. m ....
10 38
1183
1377
.86
25.1
114.5
138
6.43
Walking,4 10h 02m a. m
11 9
1052
1175
.90
27.7
109.1
134
6.16
Walking,4 10h 35m a. m
11 26
934
1117
.84
26.9
102.0
128
5.88
Carbohydrate, llh 19m a. m:
Walking,4 12h 02m p. m
10 34
1212
1336
.91
27.1
113.4
134
6.84
Walking 4 12h 43m p. m
11 23
1237
1295
.95
28.6
112.3
131
7.88
Walking,4 lh 16m p. m
10 56
1177
1221
.96
28.6
110.3
128
7.41
distance before lunch, 3,793 meters; after lunch, 10,612 meters.
2Total distance in about 5 hours of continuous walking, 23,697 meters. Pulse-rate of subject
standing during 5 consecutive minutes immediately after walking, 100, 98, 96, 96, and 98 per
minute.
3Total distance in 4 hours and 52 minutes of continuous walking, 22,919 meters. Pulse-rate
during 4 minutes soon after the carbohydrate breakfast averaged 73 per minute with the subject
sitting; during 4 consecutive minutes immediately after walking it was 80, 79, 80, and 79 per
minute, with subject standing.
4Total distance before lunch, 6,949 meters; for about 20 minutes after the first period subject
was not walking. After lunch, the distance was 9,362 meters.
STATISTICS OF EXPERIMENTS.
59
TABLE 4.^Summary of results in experiments with subject II, during the period from
Mar. 16, 1914, to May 15, 1914— "Continued.
[Values per minute.]
Date, condition, and time.
Dura-
tion.
Car-
bon
diox-
ide.
Oxy-
gen.
Respiratory
quotient.
o> .
M.2
ca cj
fc* i
« S
>3
«< &
m i ®
»23
03 •-> h
n 0. L
» S o
> f* '•*>
<!
Dis-
tance.
Steps.
Rais-
ing
of
body.
May 6.
Without food:
Standing, 8h 24m a. m
min. sec
13 7
. c.c.
229
c.c.
277
0.83
83
19.7
meters.
meters.
Walking,1 9h 42m a. m . .
10 3
1011
1124
.90
25.5
106 0
133
4 86
Walking,1 10h llm a. m
11 5
915
1101
.83
28.0
102 6
127
5 82
Walking,1 10h 44m a. m
10 3
909
1151
.79
28.0
103 6
126
6 06
Protein, Ilh31ma. m.:
Walking,1 llh 57™ a. m
9 25
1135
1298
.87
28.8
112.6
133
7 69
Walking,1 12h 30m p. m ....
10 39
1137
1318
.86
29.0
113 7
133
7 83
Walking,1 lh 13m p. m
10 32
1035
1208
.86
28.5
106 0
128
6 40
Walking,1 lh 46m p. m
9 31
1076
1307
.82
29.2
111.3
129
7 76
May 6.
Without food:
Walking,2 9h 08m a. m
8 55
1902
2068
.92
31.1
140 7
149
9 76
Walking,2 10h 31m a. m
9 30
1848
2125
.87
33.4
139 6
148
8 90
Walking,2 llh 15m a. m
8 12
1796
2279
.79
35.1
142 9
152
8 79
Carbohydrate, Ilh40ma. m.:
Walking,2 12h 45ra p. m .
8 36
2058
2147
.96
35.5
143 0
145
7 82
May 10.
Without food:
Standing, 8h 34m a. m
11 5
215
246
.87
74
18.4
Walking,3 9h 44m a. m .
8 22
2017
2232
.90
32.8
145 5
153
5 37
Walking,3 10h 47m a. m
8 14
2101
2384
.88
38.6
146.8
157
6 59
Walking,3 llh 33ra a. m
9 2
2006
2234
.90
37.1
146.6
154
8 02
Protein, 12h 15m p. m.:
Walking,3 12h 43m p. m . .
8 14
2017
2244
.90
36.0
146 5
157
7 83
Walking,3 lh 20m p. m .
8 15
2020
2249
.90
40.1
146 9
156
8 28
May 11.
Without food :
Standing, 8h 37m a. m
12 47
259
278
.93
85
20.9
Standing, swinging arms,4
9h 16m a. m
10 52
455
516
.88
20.9
Running,5 10h Olm a. m
8 19
1850
1886
.98
35.7
146 6
184
13 45
Running,5 10h 49m a. m
8 55
1755
1938
.91
36 8
146 7
183
13 89
Running,5 llh 35m a. m
8 24
1793
1964
.91
37.9
148.3
181
14 80
Carbohydrate, 12 noon:
Running,5 12h 44m p. m
8 23
1795
1910
.94
36.6
148.7
181
13 95
JTotal distance before lunch, 8,126 meters; after lunch, 9,193 meters. During about 40
minutes of the intervals between periods in the afternoon, subject was not walking but sitting.
2Total distance before lunch, 5,571 meters; after lunch, 1,543 meters. Subject perspired very
much with this rate of walking and worked with arms and hands much more than at the other
speeds. For about 1 hour and 40 minutes of the intervals between periods in the morning he was
not walking.
'Total distance before lunch, 6,307 meters; after lunch, 3,468 meters. During about 1 hour and
20 minutes of the intervals between periods in the morning and about 25 minutes in the afternoon,
subject was sitting or walking a little in the room.
4The subject swung his arms as vigorously as in the fastest walking.
6Total distance before lunch, 5,595 meters; after lunch, 1,729 meters. In running, the subject
held arms up in front of body and the only movement of the arms was that of the swaying body.
During about 1 hour and 10 minutes of the intervals between periods in the morning subject was
not running.
60
ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
TABLE 4 — Summary of results in experiments with subject II, during period from
Mar. 16, 1914, to May 15, 1914— Concluded.
[Values per minute.]
Date, condition, and time.
Dura-
tion.
Car-
bon
diox-
ide.
Oxy-
gen.
Respiratory
quotient.
« (0
2«
c3 f-
* i
D OG
51
££.8
C3 •- g
•* a A
££§
> >. '43
<!
Dis-
tance.
Steps.
Rais-
ing
of
body.
May 12.
Without food:
Standing, 9h Olm a. m
min. sec.
13 15
c.c.
226
c.c.
293
0.77
8?
20 4
meters.
meters.
Running,1 9h 45m a. m . . . .
8 19
1983
2194
.90
34 9
147 1
191
15 40
Running,1 10h 44m a. m
8 55
1758
1843
.95
37 8
148 4
183
14 09
Running l llh 38™ a. m
8 28
1723
2011
.86
39 2
148 1
182
15 40
Running l 12h 26m p. m
10 12
1752
2050
85
39 2
148 1
184
14 64
Running,1 lh 10m p. m
10 6
1734
2080
.83
40 8
148 7
176
15 37
May 13.
Without food:
Standing 10h 20m a. m .
12 27
213
257
83
79
20 2
Walking 2 llh 08m a. m
13 30
711
851
.84
25 9
82 6
117
3 76
Walking,2 llh 47m a. m
12 49
734
942
.78
27.9
89 7
120
4 51
Walking,2 12h 31m p. m
12 1
639
826
.77
27 0
80 1
112
3 29
Walking2 lh 16m p. m .
13 10
597
789
.76
25 4
76 6
106
2 84
Walking,2 2h 18m p. m
12 29
757
998
74
28 0
93 3
117
5 25
Walking,2 3h 06m p. m
13 2
753
980
.77
28.5
91.9
118
5.15
May 14.
Without food:
Standinf 8h 32m a. m
13 53
209
257
81
80
20 0
Walking,3 9h 33m a. m
7 41
2046
2281
.90
38.6
146.4
153
7.59
Running,3 10h 28m a. m . . .
7 58
1997
2272
88
37.5
146.5
168
15.44
Running,3 1 lh 20m a.m..
8 51
1646
1867
.88
38 3
147.2
183
12.47
Running,3 llh 58m a. m
9 2
1625
1900
.86
38 8
147 6
182
12.34
Running3 12h 35™ p. m . .
9 41
1701
1982
86
40 1
148 1
183
11 09
May 15.
Without food:
Standing, swinging arms,4
8h 52m a m
12 8
554
643
86
22 3
Running,5 9h 57m a. m
9 40
1735
1967
88
38 6
144.7
182
12.48
Running 5 10h 37m a. m
8 45
1727
1978
87
37 3
148.4
183
12.14
Running 5 llh 21m a. m
8 20
1647
1947
85
38 9
147 7
184
13.13
xThe total distance was 10,111 meters. During 2 5 hours of the intervals between periods
subject was sitting or walking a little in the room.
2Total distance, 21,724 meters, the walking being continuous.
3Total distance, walking and running, 9,432 meters. During about 2 hours and 11 minutes of
the intervals between periods, subject was sitting or standing.
4Subject swung his arms as vigorously as in the fastest walking.
5Total distance, 5,711 meters. During about 58 minutes of the intervals between periods,
subject was not running or walking.
DISCUSSION OF RESULTS. 61
DISCUSSION OF RESULTS.
BASAL VALUES.
In any study of walking in a horizontal direction, two main prob-
lems present themselves: first, the variations in the energy requirement
of different individuals for walking varying distances at varying
velocities, and second, the actual energy requirement for transporting
the body-weight or a superimposed load in a horizontal direction, i. e.,
the calorie output per horizontal kilogrammeter.
As has already been noted, the mechanical processes incidental
to walking, even at a moderate pace, usually involve some extraneous
muscular movements apparently not directly connected with the motion
of forward progression, such as the more or less vigorous swinging of
the arms and a not inconsiderable raising of the body-weight with each
step. Since these extraneous muscular movements do not necessarily
have an effective value in transporting the body-weight or the super-
imposed load in a horizontal direction, the problem of finding the
calorie requirement for such transportation of weight becomes an
exceedingly complicated one.
If the principle of the deduction of basal values for determining the
energy required to move 1 kilogram 1 meter in a horizontal direction
may be legitimately employed, and this has been the method adopted
by all investigators, it becomes an important point as to what should
properly be considered as the basal maintenance metabolism in experi-
ments when the subject is walking in a horizontal direction. As will
be seen by reference to the summary of previous researches given in
table 1, investigators have varied considerably in their usage in this
respect. Certain members of the Zuntz school have almost invariably
employed the resting (lying) metabolism obtained with the subject in
the post-absorptive condition. The values found with the subject
sitting or stancling quietly have also been used as a basis in determining
the metabolism due to the muscular activity of walking. Still another
basal value which may be considered is that found when the subject is
standing and moving his arms in a manner similar to that employed in
more or less rapid walking. Finally it may even be possible to use
the metabolism determined during slow walking for a basal value to
be deducted from the metabolism found while the subject was walking
at a rapid rate. The validity of this assumption will be examined later.
Bearing in mind the experience of Benedict and Cathcart in attempt-
ing to secure a suitable base-line for their bicycle rider, we considered
it desirable to study our subjects in varying positions. The positions
selected have been outlined in a preceding section. Since we were to
make a large number of observations upon each subject, we concluded
that the period of adjustment to the type of the experiment would be so
short that a moderately constant value could be found in the standing
62 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
position, and hence the greater part of our control data was obtained
in experiments with the subject standing in a relaxed position.
Although values for comparison are available for other standing posi-
tions and for the subject sitting, no studies were made by us with the
subject in complete muscular repose, i. e., lying upon a couch, in the
post-absorptive condition.
Obviously it is first necessary to examine the data thus secured to
determine the suitable basal values to be deducted from the total
metabolism while walking, such a critical examination being of funda-
mental importance. Since the total metabolism is made up of that for
maintenance, i. e., the basal value plus that for forward progression,
it is evident that the larger the value deducted for maintenance — as,
for instance, the value obtained with the subject standing as com-
pared with the subject lying on a couch — the smaller will be the result
obtained for the energy requirement for the work of forward pro-
gression.
BASAL METABOLISM OF SUBJECT I.
As a result of a consideration of the experimental experience of
others, it was decided that in the preliminary observations in this
investigation, which were made with subject I by Dr. Carl Tigerstedt,
the basal value selected should be that necessary for maintenance
while the subject was standing quietly without support. Accordingly,
during November and December 1913 many observations were made
of the subject in this position. Subsequently it appeared that more
information was desirable with regard to the normal increment in
metabolism due to a change from the lying position to the standing
position, but as a study of this phase of the question was wholly
incidental to the main problem of the metabolism during forward
progression, the experimental routine did not permit such observations.
We have, however, the results of a study made in December 1914 by
Mr. H. L. Higgins, of the Laboratory staff, upon the lying and standing
metabolism of subject I, which were kindly supplied us for comparison
with our values. Unfortunately the data thus obtained are more or
less fragmentary and must therefore be considered as only subsidiary
to the results of the larger investigation.
The Thiry valves and Tissot spirometer and mouthpiece were used in
this study, both the resting metabolism and the standing metabolism
being observed with the subject in the post-absorptive condition. We
have no data as to the influence of food upon the resting metabolism
of this subject. The results obtained by Mr. Higgins are recorded in
table 5. These values are typical of a large number secured by this
observer in another research with subject I, who shows a remarkably
uniform basal resting metabolism. As will be seen from the table, the
heat output per minute of this individual in the lying position was on
December 2 and 5, 1914, 1.23 and 1.22 calories respectively.
DISCUSSION OF RESULTS.
63
The values found by Dr. Carl Tigerstedt for subject I in the standing
position, which was the only position used by Dr. Tigerstedt in deter-
mining the basal metabolism of this subject, are given in table 6. Since
the walking experiments were made in the morning and in the afternoon
and with and without food, the basal values were also obtained in both
the post-absorptive condition and after the taking of food. The appa-
ratus used for determining the respiratory exchange was the same as
that employed for the walking experiments.
TABLE 5. — Metabolism of subject I in the lying and standing positions in experiments without
food, on Dec. 2 and Dec. 5, 1914.
[Observations made by Mr. H. L. Higgins with Thiry valves and Tissot spirometer.
Values per minute.]
Date and time.
Dura-
tion.
Carbon
dioxide.
Oxygen.
Heat
output
(com-
puted).
Pulse-
rate.
Respira-
tion-rate.
Dec. 2.
Lying, 8h 53m a. m
mins.
10
c.c.
210
c.c.
249
cals.
62
22 0
Standing, 9h 13m a. m
8
230
297
84
Standing 9h 29m a. m . . .
8
224
287
85
25 7
Lying 10h 15m a. m .
10
208
256
61
24 8
Lying 10h 35m a m
10
196
262
61
24 1
Average, Iving
205
256
1.23
61
23 6
Average, standing . .
227
292
1 39
84
25 7
Dec. 5.
Lying, 9h 02m a. m
10
219
246
62
23 4
Standing, 9h 27m a. m
8
220
269
95
25 8
Standing, 9h 44m a. m
8
217
268
90
26 4
Lying 10h 25m a. m
9
221
249
57
24 8
Average lying . .
220
248
1 22
60
24 1
Average standing
219
269
1 29
93
95 i
As will be seen from table 6, the average post-absorptive values are
reasonably constant throughout the entire period from November 28
to December 20. A striking exception is shown oh December 5, when
the average carbon-dioxide excretion was 236 c.c. per minute and the
oxygen consumption 334 c.c. per minute. The protocols for this
experiment show that "there was no sleep the night before, but much
alcohol." The pulse-rate was especially high on this particular day.
The general average for the observations without food shows a carbon-
dioxide excretion of 223 c.c. per minute and an oxygen consumption of
280 c.c. per minute. This corresponds to a heat output of 1.34 calories
per minute. The pulse-rate of this man was extremely high, averaging
94 beats per minute; the average respiration rate was 21.2 per minute.
All of these experiments were made with subject I standing with
muscles relaxed. The general uniformity of the data shows that for
the most part the subject must have assumed a standing position with
a relatively constant muscle strain, although variations are found in
64
ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
the experiments without food from 1.28 to 1.57 calories per minute.
Excluding the extraordinarily high value of December 5, which is at
least in part explained by the alcoholic excesses of the preceding night,
the uniformity in the average values is for the most part striking. It
is also of interest to note that the average value obtained for all of the
standing experiments without food during December 1913, i. e., 1.34
calories, is the same as that of the average of two standing experiments
made by Mr. Higgins in December 1914. (See table 5.) It will be
seen, therefore, that for manj^ purposes an average basal value may be
used for this subject with propriety and that it may be assumed that
when standing quietly and in the post-absorptive condition, his average
heat output would correspond to 1.34 calories per minute.
TABLE 6. — Metabolism of subject I in the standing position.
[Observations made by Dr. Carl Tigerstedt. Average values per minute.]
Date.
Carbon
dioxide.
Oxygen.
Heat-
output
(com-
puted).
Pulse-
rate.
Respira-
tion-rate.
1913.
Without food :
Nov. 28 ....
c.c.
222
c.c.
285
cals.
1.36
92
17.1
29
224
282
1 35
93
18.5
Dec 1
220
279
1 34
92
19.3
2
224
286
1.37
89
20.7
3
214
272
1.30
92
21.8
4
214
267
1.28
90
22.6
5
236
334
1.57
105
23.2
8
206
271
1.29
91
21.2
15
222
275
1.32
89
22.2
16
223
286
1 37
101
22 2
17
223
271
1.31
91
21.3
18
229
263
1.29
86
21.3
19
239
279
1.36
98
23.0
20
226
270
1.31
103
22.9
Average, without food ....
223
280
1.34
94
21.2
After breakfast:
Nov. 26
281
332
1.61
Dec. 9
248
341
1.61
112
22.9
After dinner:
Nov. 26 .
273
335
1.61
84
18.2
Average, with food .
267
336
1.61
98
19.8
When the superimposed factor in a metabolism experiment is suf-
ficiently great to increase the metabolism several hundred per cent, as
is especially the case in muscular-work experiments, the use of a pre-
viously established average basal value is least liable to objection.
Although with this particular subject we may assume that we have a
fairly well-established basal value, as a matter of fact, to eliminate
possible wide variations we rarely used this average figure and the
absolutely determined basal value for each day, which was usually
available, was given the preference.
DISCUSSION OF RESULTS. 65
INFLUENCE OF FOOD AND BODY POSITION.
In this preliminary study of subject I, we have two main factors to be
considered, namely, the influence of food and of body position.
Influence of food. — We have only three experiments in which obser-
vations were made of the standing metabolism of subject I after the
ingestion of food. Singularly enough, the average on each of these
three days shows that the heat output after the ingestion of food when
measured with the subject in the standing position was the same in all
of the experiments, i. e., 1.61 calories. (See table 6.) As we have no
basal value without food which was determined on these three days, we
must be content to note that the average basal value of 1.34 calories was
increased 0.27 calorie per minute as the result of the ingestion of food,
an increment of approximately 20 per cent. It is thus clear that prior
to the actual walking tests after meals, the subject has a noticeably
larger basal metabolism than prior to the walking experiments in the
morning in the post-absorptive condition. The intelligent use of these
basal values after food is a subject of subsequent discussion.
Influence of position. — In his experiments with subject I in December
1914, Mr. Higgins also obtained data regarding the metabolism of this
subject in the standing position. Any comparison of these values with
those obtained by us a year earlier for the same position would be a
violation of a fundamental principle in the computation of metabo-
lism experiments, notwithstanding the facts that the difference in the
body weight is but 2 kilograms and that the values obtained for the
metabolism in both cases were extraordinarily constant. Neverthe-
less, in the hope of throwing some light on the probable increment in
the metabolism to be expected from this man, when standing, we
have included in table 5 (page 63) Mr. Higgins's results of December
1914 for the standing position.
The observations on December 2 show an average heat output for the
standing position of 1.39 calories per minute, but three days later
(December 5) , when the conditions were apparently identical, the heat
output was but 1.29 calories per minute. Using the average values for
the resting (lying) metabolism on the same days, we note an increase in
the heat output on December 2 from 1 .23 calories to 1 .39 calories and
on December 5 from 1.22 calories to 1.29 calories, the average increase
being from 1.225 calories to 1.34 calories. This is equivalent to an
average increment of 0.115 calorie, or approximately 9 per cent, due to
the changing of the position from lying to standing. Since the average
value of 1.225 calories for the metabolism in the lying position is true
not only for the two days referred to but also for an extensive series of
experiments made by Mr. Higgins on this subject in 1914, and since
the average of the two standing experiments made by the same observer
is identical with the average of the long series of standing experiments
made one year previous by Dr. Tigerstedt, we may properly maintain
66
ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
that with this subject a change in the body position from lying to
standing is accompanied by an increase of approximately 9 per cent
in the total metabolism.
BASAL METABOLISM OF SUBJECT II.
With the beginning of the prolonged research on the professional
athlete subject II (the bicycle-riding subject M. A. M. of Benedict and
Cathcart), we planned definitely to secure much more extended data
as to the metabolism during various standing positions, to supplement
the preliminary data obtained with subject I by observations made on
subject II after the ingestion of food, and to determine in addition
the metabolism of the subject in the sitting position. These studies
were wholly incidental to the main problem of studying the motion
of forward progression and were made primarily with a view to illum-
inating the possible selection of the most advantageous and the most
scientifically sound base-lines. At the time the observations were made,
we were not certain of their ultimate use in the final computations, so
they may properly be considered as a study of the metabolism in the
standing and sitting positions, with and without food.
METABOLISM IN THE LYING POSITION.
The observation of the post-absorptive metabolism of this subject in
the lying position was confined to one experiment which was made
through the kindness of Mr. L. E. Emmes, of the Laboratory staff,
but a large number of basal values for this position were also available
as a result of the previous study of the subject by Cathcart. The
results obtained in the experiment made by Mr. Emmes and an average
value for the results obtained by Cathcart are given in table 7.
TABLE 7. — Metabolism of subject II in the lying position in experiments without food.
[Observations made by Mr. L. E. Emmes. Values per minute.]
Date and time.
Carbon dioxide.
Oxygen.
Heat-
output
(com-
puted).
Pulse-
rate.
Respira-
tion-rate.
Total.
Per kilo-
gram.
Total.
Per kilo-
gram.
Apr. 18, 1914 :L
8h 24m a. m
c.c.
198
186
196
193
c.c.
c.c.
226
229
229
232
c.c.
cals.
57
56
58
56
15.5
15.5
16.5
16.3
8 54 a. m
9 17 a. m
9 48 a. m
Average
193
205
2.86
3.12
229
242
3.39
3.67
1.11
1.17
57
63
15.9
20.0
Dec. 7, 1911, to Apr. 16, 19122
lThe duration of each period on April 18 was about 15 minutes and 3 seconds.
2Average of experiments made by Benedict and Cathcart. See Carnegie Inst. Wash. Pub. 187,
1913, p. 78.
DISCUSSION OF RESULTS.
67
The four periods of the respiration experiment made on April 18,
1914, by Mr. Emmes show an excellent agreement which is character-
istic of this subject. Although his nude body-weight was 1.6 kilograms
greater than at the time of the study of Cathcart, being 67.5 kilograms
on April 18, 1914, and averaging 65.9 kilograms during the previous
research, the heat output per minute was but 1.11 calories per kilogram
per minute as compared to the average of the earlier observations of
1.17 calories per kilogram per minute. While it is possible that direct
averaging in this instance is a mathematically unsound procedure, we
may state that the resting basal heat output of subject II in the post-
absorptive state may be considered to be, in round numbers, 1.14
calories.
METABOLISM IN THE SITTING POSITION.
In a further effort to secure all possible data for establishing various
scientifically sound base-lines, we made a special study of the metabo-
lism of subject II while he sat comfortably in a chair. Three observa-
tions were made with the subject in the post-absorptive condition,
four after a light breakfast, and five after a heavier midday meal.
The data are sufficiently extended to permit their classification accord-
ing to the character of the meal and such a classification is used in
presenting the results of the study of the sitting metabolism in table 8.
TABLE 8. — Metabolism of subject II in the sitting position.
[Values per minute.]
Date.
Carbon
dioxide.
Oxygen.
Heat-
output
(com-
puted) .
Pulse-
rate.
Respira-
tion-rate.
1914
Without food :
Mar. 25
c.c.
192
c.c.
260
cols.
1.23
59
18.0
27
195
234
1.13
58
17.6
Apr. 3
219
245
1.20
67
19.4
Average
202
246
1.19
61
18.3
After light meal:
Mar. 16
218
281
1.34
18.7
16
203
256
1.23
18 3
18
233
286
1.38
19.2
19
242
282
1.37
67
18.7
Average . .
224
276
1.33
18 7
After heavy meal:
Mar 16
250
304
1.47
19 9
17
213
272
1.30
18.1
18
248
297
1.44
19.3
19
259
322
1.55
77
21.0
25
272
316
1 54
73
19.6
Average
248
302
1 46
19 6
68
ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
With subject I no such classification could properly be made and,
indeed, the observations after the ingestion of food were but few in
number.
The metabolism with and without food are further compared in
table 9, to which is added the actual increase in the units of measure-
ment commonly employed for the various factors and the percentage
increase. From this table we see that as the result of a light meal the
carbon dioxide was increased 10.9 per cent, the oxygen consumption
12.2 per cent, and the heat output 11.8 per cent. After the heavy meal,
the percentage increase was essentially the same for all three factors,
i. e., 22.8 per cent. This percentage increment in the metabolism of
subject II after a heavy meal is almost identical with that noted for
subject I in the few experiments made with him.
TABLE 9. — Metabolism of subject II in the sitting position with and tvithout food.
[Average values per minute.]
Condition.
Carbon
dioxide.
Oxygen.
Heat output
(computed).
Pulse-rate.
Respira-
tion-rate.
Without food
c.c.
202
c.c.
246
cals.
1.19
61
18 3
After light meal
224
276
1.33
!67
18 7
Increase with food ....
After heavy meal . .
r 22
\ 10.9 p. ct.
248
\ 30
1 12. 2 p. ct.
302
( ^
\11.8 p. ct.
1 46
( 6
1 9 . 8 p. ct,
175
19 6
Increase with food ....
(48
\ 22. 8 p. ct,
/ 56
1 22 . 8 p. ct.
r .27
[22 . 7 p. ct.
(14
\ 23. Op. ct.
JThe pulse-rate was obtained in only one of the four periods after the light meal; in but two of
the five periods after the heavy meal. (See table 8.)
One serious objection to this type of comparison, however, and an
objection that measurably lessens the mathematical value of the incre-
ment due to food, is the fact that the periods after the midday meal
followed the walking experiment in the morning, in which there was
considerable muscular activity. As a matter of fact, the long-con-
tinued walking experiments, in which the walking was done at a rapid
rate and the muscular activity was very severe, were not carried out
until later in the spring of 1914, and hence in all probability we have
not here to consider any great after-effect of the muscular activity of
the morning which persisted throughout the experiment in the after-
noon. Nevertheless, it is quite possible that at least a part of the
excess metabolism after the midday or "heavy" meal may be explained
by the fact that the subject had done considerable walking in the fore-
noon, while no such muscular activity preceded the after-breakfast
experiments.
Of special significance here is the apparent striking relationship
between the percentage increment in the total metabolism and the
percentage increment in the pulse-rate. The increase in the heat-
DISCUSSION OF RESULTS. 69
output after a light meal was 12 per cent and that in the pulse-rate
10 per cent, while after a heavy meal the increase in the heat output
was 22.7 per cent and in the pulse-rate 23 per cent. This Laboratory
has frequently emphasized in its publications the important relation-
ship between the pulse-rate and the metabolism, the statements usually
implying that an increase in the pulse-rate is simultaneous with an
increase in the metabolism. Recently, in publishing the results of
observations on a man who fasted 31 days,1 it was pointed out in com-
paring the metabolism of the subject asleep and awake that the incre-
ment in the pulse-rate for the subject awake was directly proportional
to the percentage increase in the metabolism. While it is by no means
maintained that the increment in the pulse-rate for subject II was in
direct proportion to the increase in the metabolism, it is of special
interest to point out this second striking percentage relationship
between the pulse increment and the metabolism increment, for such a
quantitative relationship, if not partaking of the nature of a physio-
logical law, at least serves to emphasize in a striking manner the im-
portance of records of the pulse-rate in all metabolism experiments.
Occasion is here taken to note that a common error is found with
writers who misapply the measurements of the pulse-rate in attempting
to compare the pulse-rate of one person with that of another. Our
experience in this Laboratory points to no relationship between the pulse-
rate of two individuals, although the records for a single individual are
frequently surprisingly proportional to the metabolism.
COMPARISON OF THE METABOLISM IN THE LYING AND SITTING POSITIONS.
Although observations were made of the metabolism of subject II
in the post-absorptive condition for both the sitting and the lying posi-
tions, unfortunately the studies of the metabolism in the lying position
were made some three weeks later than those of the metabolism in the
sitting position, hence a comparison of the results is not free from criti-
cism. If, however, we compare the average values found for the
metabolism in the lying position on April 18, 1914 (see table 7), with
the average of the values for the metabolism in the sitting position
obtained on March 25 and 27 and April 3, 1914 (see table 8), we find a
percentage increase in the carbon-dioxide output with the subject sit-
ting over that with the subject in the lying position of 4.7 per cent, in
the oxygen consumption of 7.4 per cent, in the heat production of 7.2
per cent, and in the pulse-rate of 7.0 per cent. According to these incom-
plete data, therefore, the increase in the metabolism with the subject
sitting over that with the subject in the lying position is approximately
7 per cent.2 We may also note here the agreement between the incre-
ment in the pulse-rate and that of the total metabolism.
Benedict, Carnegie last. Wash. Pub. 203, 1915, p. 351.
2See, also, Emmes and Riche, Am. Journ. Physiol., 1911, 27, p. 406.
70 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
METABOLISM IN VARIOUS STANDING POSITIONS.
With subject I no attempt was made to vary the character of the
standing experiment, but with subject II numerous observations were
made both with and without food and with the subject standing in
various positions. A large majority of the experiments, i. e., 53 experi-
ments, were made when the subject was standing quietly in a relaxed
position. Eight experiments were made with the subject standing in a
relaxed position, but resting the hands upon a staff. Eight experiments
were made with the subject leaning against a support, and finally 10
experiments were carried out with the man standing in the position
of "attention." Since later we noted that there was considerable
extraneous muscular activity incidental to walking at a rapid rate,
which consisted for the most part of vigorous arm-motion, two experi-
ments were made on May 11 and 15 in which the post-absorptive
metabolism was measured with the subject standing still but moving
his arms vigorously, simulating as nearly as possible the movement of
the arms in rapid walking.
The results of the standing experiments with the subject in the post-
absorptive condition will first be considered and are given in table 10.
Since our interest is chiefly with the total heat-output, we may properly
compare the metabolism in the various standing positions upon this
basis.
When the subject stood in a relaxed position, his heat output varied
from the very low value of 1.12 calories to 1.40 calories per minute, the
average value being 1.25 calories per minute. When he stood in a
relaxed position, but with his hands resting upon a staff, the average
heat-output was essentially the same as in the first position, namely,
1.26 calories per minute; but when he leaned against a support there
was a perceptible diminution in the heat-output, which then averaged
but 1.18 calories per minute. It is, however, somewhat irregular to
compare an average value for the relaxed position obtained from 26
experiments with the average values for other positions obtained from
only 3 experiments ; the slight changes in the metabolic level shown by
these averages are therefore probably without significance. Essen-
tially the same may be said of a comparison of the values obtained for
the relaxed position with those obtained for the position of attention
when the heat output increased only to 1.30 calories. Our general
impression was that this subject did not maintain, to any great degree,
a rigid position of " attention." From the foregoing comparison it is
clear that the experimental evidence does not warrant the deduction
that there is a measurable difference in the metabolism for any of the
various standing positions in which the metabolism was studied, such
as standing in a relaxed position, with the hands on a staff, with the
subject leaning against a support, or standing in the position of
"attention."
DISCUSSION OF RESULTS.
71
When instead of the muscular repose of these standing positions the
subject swings his arms vigorously, as would be done in rapid walking,
we note a great increase in the metabolism. Unfortunately there is
not a particularly satisfactory agreement in the values obtained for the
two experiments under these conditions, for on May 11 the heat-output
per minute was 2.53 calories, or essentially 100 per cent greater than
when the subject stood quietly, while on May 15 the metabolism was
3.13 calories or approximately 150 per cent greater than the metab-
olism of the subject when standing at rest.
TABLE 10. — Metabolism of subject II standing in different positions in experiments without food.
[Values per minute.]
Date.
^i
o
•3
gl
X!
u
a
U
Oxygen.
Heat-output
(computed).
<D
•*3
?
<a
a>
3
PL,
Date.
X
_o
•3
-i ®
%3
42
*-«
e3
O
Oxygen.
Heat-output
(computed).
6
+3
a
i
<D
to
(5
1914
Standing, relaxed:
Mar 20
c.c.
218
c.c.
275
cals.
1 32
71
1914
Standing, staff:
Mar. 24
c.c.
217
c.c.
250
cals.
1 22
82
31
209
260
1 25
71
26. . .
223
253
1 24
80
Apr 1
213
266
1.28
75
Apr. 3
224
278
1.34
77
f\
218
94fi
1 ?1
74
[214
257
1 24
8°,
Average
221
260
1.26
80
7
<
on
8
[iys
204
2oo
265
. 14
1.26
yu
9
202
228
1.12
82
Standing, support:
10
212
257
1 24
78
Mar. 24
196
256
1 22
79
14
223
245
1 21
94
26
201
238
1.15
79
15
214
252
1.23
74
31
214
239
1.17
77
16
958
1 9fU
90
17
214
265
1.28
85
Average
204
244
1.18
78
91
onr;
9.4.9
I 1C
78
22
207
251
1.21
84
23 . .
208
252
1.22
74
Standing, attention:
24
198
1.15
8?,
Mar. 25
206
265
1.27
79,
25
192
264
1 24
79
27
219
272
1.31
71
27
217
245
1.20
77
31
233
272
1.33
75
00
991
974
1 V>
82
May 5
229
277
1 34
83
Average
219
270
1.30
73
i n
91 <%
94fi
1 90
74.
11
259
278
1.38
85
12
226
293
1.40
8?,
Standing, swinging
13
213
257
1.24
79
arms :2
14
209
257
1.24
80
May 11
455
516
2.53
15
554
643
3 13
Average
214
258
1.25
80
lfrhe average respiratory quotient of 0.83 is assumed in computing heat-output on this day.
2The subject stood swinging his hands and arms as vigorously as in the most rapid walking.
In the subsequent computations several basal values may be em-
ployed. The most obvious are those obtained with the subject in the
lying position and, as has already been seen, we have the results of two
series of measurements which were made with an interval of approxi-
mately two years. We have also used the value obtained with the
subject in the standing position. With subject I, three periods with
72
ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
the subject standing almost invariably preceded the periods when the
subject walked on the treadmill, but with subject II only one standing
period preceded the walking periods. With subject II, therefore,
instead of using the daily values found for the standing position, we have
employed the average value found for the whole series of experiments,
i. e., 1.25 calories per minute. Special use will be made of the values
found while the subject stood swinging his arms.
INFLUENCE OF FOOD UPON METABOLISM IN THE STANDING POSITION.
The experiments in which the subject was studied after the ingestion
of food varied not only in the character of the food taken, but in the
amount of food, the influence of both a light and a heavy meal being
observed.
INFLUENCE OF A LIGHT MEAL.
As we have seen from the data given in the historical summary table
(table 1), it has been the custom of several investigators to make
walking experiments after the subject had taken a moderate amount of
food. We felt it important, therefore, to make observations under
these conditions, since they would give information as to how long the
TABLE 1 1 . — Metabolism of subject II standing in different positions after a light meal.
[Values per minute.]
Date.
X
o
-3
I1
d
O
Oxygen.
Heat-output
(computed).
o5
-»j
!
o>
to
1
Date.
«
o
•3
_ 6
%3
JZ
r-i
o3
0
Oxygen.
Heat-output
(computed).
0)
-*j
?
j
fS
1914
Standing, relaxed:
Mar. 16
c.c.
(217
c.c.
274
cats.
1.31
1914
Standing, support:
Mar. 28
c.c.
f279
c.c.
304
cals.
1.50
87
18 ... .
[223
224
286
293
1.37
1 42
Apr. 2
\246
273
276
306
1.36
1 50
81
89
19
231
295
1 41
•7*.
21
271
338
1.62
98
Average
266
295
1 45
86
Anr 2
21S
281
1 38
8fi
Average
240
295
1 42
Mar. 21
249
288
1 41
91
Qn
Ofil
971
1 '^
7fi
Apr. 2 .
248
268
1 33
78
Mar. 23
282
333
1 62
74
Average . .
253
276
1 37
82
*?0
2fi1
9QA
1 4^
71
Average . .
272
315
1 54
73
periods
253
294
1 43
82
ingestion of food influences metabolism when accompanied by muscular
activity. With subject II the first meal of the day was usually a mod-
erately light meal; accordingly on certain days he was permitted to
eat breakfast before coming to the Laboratory for the experiments.
The results of the standing experiments after the morning meal are
given in table 11. When the subject was standing in a relaxed posi-
DISCUSSION OF RESULTS. 73
tion, the heat output averaged 1.42 calories per minute, this being an
average value for 6 experiments. But two experiments were made with
the subject standing with his hands resting on a staff, the average
results being 1.54 calories, or somewhat higher than the average for
the previous position. When standing in a relaxed position but
leaning against a support, the subject had an average heat-output for
three experiments of 1 .45 calories per minute, while the same number of
experiments with the subject in the position of "attention" gave
an average heat-output of 1.37 calories. Obviously variations in the
kinds and amounts of food must to a certain extent affect not only the
individual values for the different days, but also the average values for
the several groups ; nevertheless the general statement made in consid-
ering the standing experiments with the subject in the post-absorptive
condition, namely, that the metabolism was essentially the same for all
of the four standing positions in which the metabolism was studied, also
holds true here.
Averaging all of the values obtained in the standing experiments
after the ingestion of a light meal, we find that the carbon dioxide per
minute was 253 c.c., the oxygen consumption 294 c.c., and the heat-
output 1.43 calories per minute. With the exception of the walking
experiment on April 29, when a heavy carbohydrate breakfast was
given as a control, the average value of 1.43 calories has been used as
a basal value in calculating the increase in the heat-output during
walking for all experiments after breakfast. For the walking experi-
ment of April 29, the average basal value used for the computation of
the increment due to walking was that obtained from the standing
experiments of April 25 and 27 after a carbohydrate lunch had been
taken (see table 12), this being the most logical value available for the
purpose.
INFLUENCE OF A HEAVY MEAL.
At noon subject II usually took a heavy meal and frequently returned
to the Laboratory for a walking experiment in the afternoon. During
April 1914 the character of the noon meal was controlled on several
days. On 5 days he was given a meal of which the constituents were
excessively high in protein; on 6 days the meal was particularly rich
in carbohydrates; and on 4 days it was especially rich in fat. No
attempt was made to control the amount eaten, although the statement
was made that the " subject ate all that he could."
The values for all of the measurements made in the various standing
positions after this noon meal are given in table 12. Comparing first
the results obtained in the several standing positions and excluding
the days with special diets, we find that the heat-output averages
1.56 calories when the subject stood in a relaxed position, 1.65 calories
when he stood with the hands resting upon a staff, 1.47 calories when
he leaned upon a support, and 1.52 calories when he stood in a position
74
ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
of " attention." All of these values were obtained after a heavy meal,
with the diet uncontrolled. Recognizing again the probable influence
of the preceding meal upon the individual values, we see, nevertheless,
that the evidence points towards a practically constant metabolism
independent of the variations in the standing position under approxi-
mately similar conditions.
TABLE 12.— Metabolism of subject II standing in different positions after a heavy meal.
[Values per minute.]
Date and conditions
of experiments.
M
o
•B
a
o
Oxygen.
Heat-output
(computed).
Pulse-rate.
Date and conditions
of experiments.
i
-8
Jl
(H
03
0
Oxygen.
Heat-output
(computed).
Is
J2
1914
Diet uncontrolled:
Standing, relaxed:
Mar. 16. ...
c.c.
261
c.c.
319
cals.
1.54
1914
Diet controlled:
Standing, relaxed :
Protein —
c.c.
c.c.
cals.
19 .
247
303
1 46
86
Apr 6
241
296
1 43
20
274
318
1 55
87
7
217
289
1 37
21
275
355
1 70
96
8
230
275
1 33
31
277
345
1.66
89
23
223
254
1 24
81
Apr. 1
283
319
1.57
86
24
219
299
1 41
94
Q
244
9QQ
1 42
81
.
OOfi
000
1 °.fi
RS
266
°,99
1 ^fi
88
...
Standing, staff:
Carbohydrate —
Apr. 9. ...
245
295
1.43
76
Mar. 24
289
356
1 71
95
10
264
301
1 47
86
26
274
317
1 55
94
14
242
295
1 42
90
30
318
339
1.69
95
15
267
277
1 38
83
974
°,94
1 KO
00
Average
294
337
1.65
95
27
294
326
'l 61
75
Standing, support:
Average
264
303
1.48
82
M-ir 94
9<yi
Qf)1
i 4«
99
26.
254
289
1 42
93
Fat —
28
280
314
1 54
85
Apr 16
239
292
1 41
98
i 7
901
9X1
1 '^fi
on
Average
263
301
1.47
90
21
220
301
1 42
91
99
997
oqq
1 49
Q'3
Mar. 21
270
295
1.46
94
Average
229
293
1 40
95
25
292
309
1 54
95
27
294
298
1 50
95
31
265
326
1 57
89
Average
280
307
1 52
93
Average of all
periods
274
317
1 55
91
During the observations made with the specially controlled diets, the
subject stood in the relaxed position, without leaning upon a staff or
against a support. These show an average value of 1.36 calories for
the protein diet, 1.48 calories for the carbohydrate diet, and 1.40
calories for the fat diet, values not strikingly unlike those found on the
days with an uncontrolled diet. We may then with propriety average
DISCUSSION OF RESULTS. 75
the results obtained for the four groups of experiments in the relaxed
position, i. e., one group with an uncontrolled diet and three with con-
trolled diets, and state that after the midday meal our subject showed
with considerable constancy an average heat-output of 1.45 calories
per minute.
From the values obtained in the experiments with the subject stand-
ing after a heavy meal, basal values were computed for use in calculat-
ing the increment due to walking under the same conditions of diet.
Considering first the results obtained with an uncontrolled diet, we
averaged the values determined with the subject standing in the four
positions, i. e., relaxed and unsupported, relaxed with the hands resting
upon a staff, relaxed and leaning against a support, and the position of
"attention." The averages found were 274 c.c. for the carbon-dioxide
production, 317 c.c. for the oxygen consumption, and 1.55 calories for
the heat-output. These averages were used for basal values in calculat-
ing the increase in the metabolism due to walking for all of the experi-
ments following a heavy meal with an uncontrolled diet.
The average value found on the days with a diet rich in protein,
namely, 1.36 calories, was used as a base-line for the walking experi-
ments on May 5 and 10, as the standing metabolism was not determined
on those days after the protein meal. A heavy protein meal was also
taken on April 6, 7, 23, and 24, and both the standing metabolism and
the metabolism during walking were determined. The standing values
for the individual days were therefore used as the basal values for com-
puting the increment due to walking.
The average value for the carbohydrate days was not used as a basal
value for any of the walking experiments. For the walking experi-
ments following the midday meal on May 4, 6, and 11, an average of
the values obtained on April 25 and 27, i. e., 1.59 calories, was used as
a base-line in the computations, as the diets were considered to be more
nearly comparable on those days. As has previously been stated, this
basal value was also used for the walking experiment following the
carbohydrate breakfast on April 29. For the experiments on April 9,
10, 14, 15, 25, and 27, the standing metabolism determined for that
day was used as a basal value for the respective walking experiments
which were subsequently made on that day.
On days when the diet was excessively rich in fat, the standing
metabolism was always determined before the walking experiment and
the values found were used as base-lines for the individual days, no use
being made of the average value.
CONCLUSIONS REGARDING INFLUENCE OF FOOD UPON THE STANDING METABOLISM.
The average value for the metabolism in the standing experiments
without food, as shown in table 10, was approximately 1.25 calories.
After the light morning meal, the metabolism was 1.43 calories (see
76 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
table 11) and after the heavy noon meal 1.45 calories. There was,
therefore, an average increment of approximately 0.2 calorie or 16 per
cent, due to the ingestion of the food. This value is strikingly in agree-
ment with that found with subject I, and we may accordingly state
that the basal metabolism of both subjects used in the research was
increased approximately 16 per cent by the ingestion of the kinds and
amounts of food consumed. This has an important bearing upon the
subsequent calculations, for it is obviously impossible to make an intelli-
gent comparison of the standing values obtained with individuals in the
post-absorptive condition with those obtained after the ingestion of food.
Finally, it should not be forgotten that a part, at least, of the incre-
ment ascribed here to the ingestion of food, particularly after the noon
meal, may be due to a slight after-effect of the muscular activity of
walking in the forenoon experimental periods. On the other hand,
there is such a close agreement between the increment in the metabolism
after the light meal, which was invariably taken before the morning
walking periods, and the increment in the metabolism after the midday
meal, that it would imply that the influence of the morning work must
have been extremely small.
METABOLISM DURING WALKING.
The preliminary study of the mechanics of position incidental to
walking was obviously only for the purpose of throwing light upon the
various mechanical processes involved in walking and the metabolism
essential thereto. The primary purpose of the research was to study
the actual metabolism during the motion of forward progression.
WALKING EXPERIMENTS WITH SUBJECT I.
The first series of walking experiments was made by Dr. Tigerstedt
with subject I in the month of December 1913. These experiments
were all carried out under practically the same conditions, — that is,
following two or three periods when the subject stood in a relaxed
position during which time the basal standing metabolism was meas-
ured. The body-weight of the subject was a practically constant
factor, as it did not alter materially throughout the month. An
attempt was made to maintain an essentially constant speed of the
treadmill, the rate averaging not far from 76 meters per minute. In a
few of the experiments, the speed was lowered to about 65 meters per
minute, but in no instance did it exceed 80 meters per minute. Under
these conditions we may consider that the study was based upon a
constant speed and that accordingly all values are strictly comparable
so far as the velocity is concerned. The walking experiments con-
sisted of two or three and occasionally four periods per day. On two
days walking experiments were made after the ingestion of food.
DISCUSSION OF RESULTS. 77
The results of all of the walking experiments with subject I are given
in abstract in table 13. Inasmuch as the experience of previous
investigators has shown that the variations in velocity play an impor-
tant role in the total energy transformations, we have recorded here
the distance per minute which the subject walked and have likewise
computed the number of horizontal kilogrammeters by multiplying
the distance per minute by the body-weight. From the kymograph
records it was possible to find the average height to which the body was
raised at each step by obtaining the average height of each recorded
movement; by multiplying this average height by the number of steps,
the total distance that the body was moved in a vertical direction could
be computed with reasonable accuracy, thus giving a component
for the analysis of the various factors involved in walking. The
measurements of the distance that the body was elevated per minute
are recorded in column d.
The total heat-output was calculated from the gaseous exchange not
only for the walking periods but also for the standing periods preceding
the walking; these values are recorded in column e. The increase due
to walking was obtained by difference and the energy required to move
1 kilogram 1 meter in a forward direction, i. e., 1 horizontal kilo-
grammeter, is recorded in gram-calories in column g. These latter
values are obviously the most important result of this study.
EXPERIMENTS WITHOUT FOOD.
Considering first the values without food, it will be seen that the
heat-output per horizontal kilogrammeter varies from a minimum of
0.446 gram-calorie to a maximum of 0.637 gram-calorie, but the large
majority of the values lie close to the average value of 0.507 gram-
calorie. A general inspection of these results shows indications of a
periodicity or rhythm in the efficiency of this subject in walking. Thus,
low values are found on December 2 and 3, which are followed by a
group of high values continuing until December 22, while the last
three experimental days that the subject was without food give dis-
tinctly lower values than those found in the preceding group. There
is not, however, sufficient regularity in this rhythm to indicate the
effect of training of the subject or in the use of the treadmill. To be
sure, the first value, that of November 29, is considerably higher than
the average and it is probably fair to assume that the high value of
0.637 gram-calorie found on December 15 was more or less accidental.
On the other hand, we see no reason why these values should be rejected
and the figures are sufficiently numerous to make it immaterial whether
or not these or any other particular values are discarded so far as the
influence upon the general average is concerned. While it may appear
that the low values found on the last three days would imply the effect
of training, it should be stated at the outset that this subject was a
78
ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
TABLE 13. — Increase in heat-output during walking in experiments with subject I.
[Observations made by Dr. Carl Tigerstedt.]
Date and condi-
tions of experi-
ments.
(a)
Body-
weight
with
clothing.
(&)
Distance
per
minute.
(c)
Horizontal
kilogram-
meters.
(0X6).
(d)
Raising
of body
per
minute.1
Heat-output (computed).
(e)
Total,
per
minute.
Increase over standing.
(/)
Total.
(a)
Per horizontal,
kilogrammeter
(/-c).
1913
Without food.
Nov. 29 :
Standing2. . .
Walking ....
Dec. 1:
kilos.
72.50
meters.
75.1
76.0
76.6
76.2
76.8
76.5
77.2
77.5
77.7
77.7
78.2
75.7
78.2
79.0
76.5
78.6
79.3
79.7
74.2
75.6
76.3
76.3
75.1
76.7
77.6
75.0
76.4
78.1
78.6
meters.
3.15
3.26
3.36
3.20
4.62
3.57
3.62
3.68
3.41
3.68
3.57
3.57
4.10
4.10
3.52
3.78
4.04
4.15
3.68
3.83
3.94
3.99
3.89
3.99
4.20
3.73
3.89
4.15
4.15
cols.
1.35
4.41
1.34
4.10
4.35
1.37
4.03
4.10
1.30
4.07
4.07
4.19
1.28
4.19
4.22
4.14
1.57
4.43
4.50
4.68
1.29
4.02
4.29
4.27
4.39
1.32
4.73
4.33
4.24
4.20
1.37
4.30
4.18
3.91
1.31
3.99
4.12
4.20
4.33
caZs.
3.06
2.76
3.01
2.66
2.73
2.77
2.77
2.89
2.91
2.94
2.86
2.86
2.93
3.11
2.73
3.00
2.98
3.10
3.41
3.01
2.92
2.88
2.93
2.81
2.54
2.68
2.81
2.89
3.02
gm.-cal.
0.562
.500
.541
.477
.486
.497
.493
.512
.513
.518
.501
.521
.517
.543
.493
.528
.520
.538
.637
.552
.531
.524
.541
.509
.454
.491
.505
.508
.528
5,445
Walking. . . .
Dec. 2:
Standing
72.60
5,518
5,561
Walking ....
Dec. 3:
73.12
5,572
5,616
Walking ....
Dec. 4:
Standing
72.80
5,569
5,620
5,642
Walking. . . .
Dec. 5:3
Standing
73.01
5,673
5,673
5,709
Walking ....
Dec. 8:
Standing
72.51
5,489
5,670
5,728
Walking ....
Dec. 15:
Standing
72.33
5,533
5,685
5,736
5,765
Walking ....
Dec. 16:
Standing
72.10
5,350
5,451
5,501
5,501
Walking. . . .
Dec. 17:
Standing
72.05
5,411
5,526
5,591
Walking ....
72.82
5,462
5,563
5,687
5,724
1Computed from the average elevation of the body per step as obtained from the kymograph
records and the steps per minute. See table 3 for information regarding number of steps.
2Usually three periods with the subject standing preceded the walking experiment.
3"No sleep but much alcohol" on the night preceding the experiment of Dec. 5.
DISCUSSION OF RESULTS.
79
TABLE 13. — Increase in heat output during walking in experiments with subject I — Continued.
[Observations made by Dr. Carl Tigerstedt.]
Date and condi-
tions of experi-
ments.
(a)
Body-
weight
with
clothing.
(b)
Distance
per
minute.
(c)
Horizonta
1 •!
kilogram-
meters.
(0X6).
(d)
Raising
of body
per
minute.1
Heat-output (computed).
(e)
Total
per
minute.
Increase over standing.
(/)
Total.
(a)
Per horizontal
kilogrammeter.
C/-*-c).
1913
Without food —
Continued.
Dec. 18:
Standing
kilos.
meters.
75.3
76.4
76.7
76.9
76.1
77.9
78.3
78.7
76.2
77.7
78.6
78.9
76.3
65.9
77.4
67.5
75.9
66.4
76.9
66.4
78.4
65.2
78.6
65.1
meters.
3.52
3.68
3.68
3.73
3 . 83
3.99
4.10
4.20
3.68
4.04
4.20
4.25
4.07
3.17
4.28
3.41
3.97
3.07
4.08
3.30
4.06
3.02
4.13
3.02
cals.
1.29
3.98
4.09
4.19
4.22
1.36
4.29
4.23
4.26
4.26
1.31
4.00
4.28
4.43
4.48
21.34
4.21
3.76
4.23
3.74
21 . 34
4.03
3.55
4.14
3.66
21.34
4.07
3.46
4.07
3.48
cals.
2.69
2.80
2.90
2.93
2.93
2.87
2.90
2.90
2.69
2.97
3.12
3.17
2.87
2.42
2.89
2.40
2.69
2.21
2.80
2.32
2.73
2.12
2.73
2.14
gm .-cal.
.478
.490
.506
.510
.519
.497
.499
.497
.475
.514
.534
.541
.510
.498
.506
.482
.481
.451
.494
.474
.477
.446
.476
.451
Walking. . . .
Dec. 19:
Standing
74.76
5,629
5,712
5,734
5,749
Walking ....
Dec. 20:
Standing
74.17
5,644
5,778
5,808
5,837
Walking ....
Dec. 22:
Standing ....
74.31
5,662
5,774
5,841
5,863
Walking. . . .
Dec. 23:
Standing ....
73.77
5,629
4,861
5,710
4,979
Walking ....
Dec. 27:
Standing
73.75
5,598
4,897
5,671
4,897
Walking ....
Average. . .
With food.
Nov. 26:
Standing ....
72.96
5,720
4,757
5,735
4 , 750
73.10
75.9
3.78
2.81
.507
75.3
76.0
78.3
79.1
3.57
3.68
3.89
4.04
1.61
5.03
1.61
4.61
4.39
4.33
3.42
3.00
2.78
2.72
!e20
.546
.491
.475
Walking ....
Dec. 9:
Standing
73.30
5,519
Walking ....
72 . 33
5,497
5,663
5,721
Computed from the average elevation of the body per step as obtained from the kymograph
records and the steps per minute. See table 3 for information regarding number of steps.
2Average of "standing" values obtained in experiments without food, Nov. 29-Dec. 20.
80 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
trained athlete, and although not particularly careful of himself, when
out of training, he was nevertheless in reasonably good condition. The
fact that alcoholic excesses preceded the experiment on December 5
shows, of itself, that the subject was not in strict training. Indeed, it
was impossible for us to control him outside of the Laboratory.
In considering the values without food, it is of interest to note the
variations in the standing metabolism in their relation to the total
increase due to walking. While we find from the values given in table
6 that the average heat-output for this man without food was 1.34
calories per minute, it will be seen here that the variations ranged from
1.28 calories per minute on December 4 to 1.57 calories on December 5.
The latter date was the day following the alcoholic excesses and it may
be noted that this increase in the basal metabolism continued through-
out the walking periods, as the three highest values for the heat-output
during walking were found on this day. On the other hand, when the
high basal metabolism is deducted, the gram-calories per horizontal
kilogrammeter are essentially the same as the average value.
EXPERIMENTS WITH FOOD.
On the two days in which experiments were made with subject I
after the ingestion of food, the standing or basal metabolism was per-
ceptibly higher than in the experiments without food. The total
metabolism during walking was likewise higher in all of the experi-
mental periods. On the other hand, when the standing or basal metab-
olism is deducted, we find that the gram-calories per horizontal kilo-
grammeter were, in the second experiment, quite within the normal
limits. We can find no explanation for the high value obtained on the
first day. The fact that the high basal metabolism due to food per-
sisted through the walking period is of special interest, as it shows that
the muscular activity incidental to the amount and rate of walking in
these experiments resulted in a metabolism which was superimposed
upon the increased metabolism due to the ingestion of food. In
general, we may say that when this subject walked on a level plane,
the energy required over and above maintenance to move 1 kilogram
over a distance of 1 meter, i. e., 1 horizontal kilogrammeter, was in
round numbers 0.5 gram-calorie. The correlation between these
results and those obtained with subject II and the earlier observations
of Benedict and Cathcart may properly be deferred until the discussion
of the experiments with subject II.
ENERGY REQUIRED FOR THE ELEVATION OF THE BODY.
In walking at the average speed of 75.9 meters per minute, we find,
from the records obtained with Dr. Tigerstedt's tracing pointer and
by counting the number of steps, that the total distance per minute that
the subject raised his body in a vertical direction amounted, on the
average, to 3.78 meters per minute. With an average body-weight of
DISCUSSION OF RESULTS. 81
73.1 kilograms, this would correspond to a work equivalent of 276.32
kilogrammeters or 0.65 large calorie per minute. Since the total
increase over the standing metabolism due to walking averaged 2.81
large calories per minute, it is seen that approximately 23 per cent of the
energy required for the work of forward progression was employed in
raising the body in a vertical direction.
These experiments give no data regarding the amount of energy
required to lower the body after being raised at each step. Various
assumptions are found for this in the literature, ranging from one-
quarter to three-quarters of the work done in the elevation of the body,
but it is obviously out of place to attempt such gross interpretations
of the results.
In conclusion, then, we may say that when walking in a horizontal
direction at the rate of 76 meters per minute, a man with a body-weight of
73 kilograms produces 2.81 calories per minute above his standing basal
metabolism, of which 0.65 calorie or 23 per cent is required to raise the
body through a distance of approximately 4 meters per minute. It is
thus apparent at the outset that a very important factor in the energy
consumption while walking in a horizontal direction may be the type of
step employed. Unfortunately our observations were not made upon a
sufficient number of persons to permit a complete discussion of this point.
WALKING EXPERIMENTS WITH SUBJECT II.
Subject II, who was a professional athlete, though not in continuous
training, had exercised excessively in bicycle riding and had been the
subject in Cathcart's research on the muscular work of bicycle riding.
He had done a considerable amount of walking when in training, but
was not an especially well-trained walker and certainly could not be
classed as a professional pedestrian. On the other hand, he performed
all of the tests on the treadmill at even the highest speeds with perfect
ease and was at no time unduly distressed.
The walking experiments with this subject covered a period of
approximately two months, i. e., from March 16 to May 15, 1914.
About 40 per cent of the experiments were made without food; the
remainder of the experiments followed either the breakfast or the mid-
day meal, the diet in some cases being controlled. The speed of rota-
tion of the treadmill varied during the experiments without food from
56.0 meters per minute to 146.8 meters per minute and in a few experi-
ments, with the subject running, it increased to 148.7 meters per
minute. The greater part of the experiments were made with a speed
between 56.0 and 93.3 meters per minute.
In computing the energy per horizontal kilogrammeter, we have the
same problem to consider that was met with in the case of subject I,
namely, the selection of a suitable base-line. As the tests with sub-
ject II were more varied than those with the first subject, at least
82 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
three base-lines are possible, if not indeed permissible. These are, (1)
the average resting value with the subject standing in a relaxed posi-
tion, without support, which was obtained in 25 experimental days from
March 20 to May 14, 1914, this value being 1.25 calories per minute;
(2) the average resting, lying value of 51 experiments in 1911-12 by
Benedict and Cathcart, this being 1.17 calories per minute, referred to
here as lying value I ; and (3) the resting lying basal value found as an
average of four experimental periods on April 18, 1914, namely, 1.11
calories per minute, referred to here as lying value II. The subject in
all these experiments was without food.
EXPERIMENTS WITHOUT FOOD.
All of the experiments without food for subject II have been brought
together in table 14 and are arranged chronologically, the only dis-
turbance in this order being for the experiment on May 13. The change
in position for the experiment of May 13 was made to bring the results
more nearly in the order of the increasing velocity of walking. The
heat-output per horizontal kilogrammeter for each experiment has been
computed in gram calories on the three base-lines previously cited.
The results using a basal value obtained with the subject standing in a
relaxed position are given in column g; those with an average basal
value obtained by Benedict and Cathcart in their experiments between
December 7, 1911, and April 16, 1912 (lying value I), are given in col-
umn h; and those with a basal value obtained from the special experi-
ment made by Mr. L. E. Emmes on April 18, 1914 (lying value II),
are given in column i. Inasmuch as the values for the subject standing
relaxed were determined specifically for this research, and hence in
this particular, at least, are more appropriate than the other basal
values used, we shall lay great stress in our discussion upon the incre-
ments computed from this base-line.
A general inspection of the values in column g shows that there is
a tendency towards constancy until May 4, at which time the rate of
walking first exceeded 100 meters per minute. Considering the
experiments when the speed was below 100 meters per minute, we
find 57 periods with speeds ranging from 56 to 93.3 meters inclusive,
the average speed being 71.5 meters per minute and the energy require-
ment for one horizontal kilogrammeter averaging 0.493 gram-calorie.
An inspection of the table shows considerable variation above and
below these average figures in isolated cases as, for instance, on April
15, when in one period the heat output per horizontal kilogrammeter
was 0.603 gram-calorie. On the other hand the value of 0.555 gram-
calorie is exceeded but six times and the individual values fall below
0.45 gram-calorie likewise only six times out of the 57 periods. It is
thus clear that the value 0.493 gram-calorie is distinctly representative
of the heat requirements for moving 1 kilogram 1 meter at speeds
ranging from 56 to 93.3 meters per minute.
DISCUSSION OF RESULTS.
83
TABLE 14. — Increase in heat-output during walking in experiments with subject II without food.
(a)
(&)
(c)
(d)
Heat-output (computed).
(\
/ f\
Increase per kilogram-
Date and condi-
tions of experi-
ments.
Body-
weight
with
cloth-
ing.
Dis-
tance
per
minute.
Horizon-
tal kilo-
gram-
meters
(0X6).
Raising
of body
per
minute.
e)
Total
per
minute.
(J)
Increase
above
standing
relaxed.
meter (gram-calorie.)
to)
Above
standing
relaxed
(A)
Above
lying,
I.
W
Above
lying,
II.
1914
Standing, re-
kilos.
meters.
meters.
cals.
cals.
gm.-cal.
gm.-cal.
gm.-cal.
laxed^
1.25
1.17
T vine II3
1.11
Walking :
Mar 20
72 A
/4\
2.61
3.48
2.23
1VA dl * £J\J • •
24. .
72.0
60.6
4,363
1.09
3.74
2.49
0.571
0.589
0.603
25. .
72.0
60.6
4,363
1.77
3.40
2.15
.493
.511
.525
26..
72.0
62.7
4,514
3.09
3.42
2.17
.481
.498
.512
27..
72.0
57.6
4,147
2.09
3.15
1.90
.458
.477
.492
31. .
72.0
57.2
4,118
2.01
3.27
2.02
.491
.510
.525
Apr. 1 . .
72.0
59.3
4,269
2.22
3.36
2.11
.494
.513
.527
3. .
72.0
76.2
5,486
2.38
4.39
3.14
.572
.587
.598
6. .
72.0
57.8
4,161
1.78
3.32
2.07
.498
.517
.531
56.8
4,090
1.83
3.25
2.00
.489
.509
.523
56.0
4,032
1.91
3.20
1.95
.484
.503
.518
7. .
72.0
59.6
4,291
1.98
3.53
2.28
.531
.550
.564
58.2
4,190
1.95
3.19
1.94
.463
.482
.496
8..
72.0
76.1
5,479
3.01
4.45
3.20
.584
.599
.610
77.6 5,587
2.81
3.97
2.72
.487
.501
.512
78.3 5,637
2.85
3.89
2.64
.468
.483
.493
9..
72.0
59.3 4,269
1.92
3.40
2.15
.504
.522
.536
58.8 4,233
2.05
3.20
1.95
.461
.480
.494
59.0 1 4,248
1.98
3.36
2.11
.497
.516
.530
10. .
72.0
77.3
5,566
2.77
4.09
2.84
.510
.525
.535
78.9
5,681
3.21
4.09
2.84
.500
.514
.525
14. .
71.9
61.7
4,436
2.45
3.43
2.18
.491
.509
.523
62.1
4,465
2.34
3.28
2.03
.455
.473
.486
62.4
4,487
2.37
3.26
2.01
.448
.466
.479
15. .
71.5
77.2
5,520
3.33
4.58
3.33
.603
.618
.629
79.4
5,677
3.52
4.02
2.77
.488
.502
.513
80.2
5,734
3.49
4.04
2.79
.487
.501
.511
16. .
71.5
61.9
4,426
2.38
3.16
1.91
.432
.450
.463
62.3
4,454
2.37
3.22
1.97
.442
.460
.474
61.8
4,419
2.20
3.21
1.96
.444
.462
.475
17. .
71.5
76.6
5,477
3.36
4.36
3.11
.568
.582
.593
78.1
5,584
3.45
3.94
2.69
.482
.496
.507
79.3
5,670
3.80
4.14
2.89
.510
.524
.534
21. .
70.5
60.8
4,287
2.32
3.13
1.88
.439
.457
.471
22..
70.5
76.8
5,415
3.33
3.91
2.66
.491
.506
.517
78.6
5,542
3.44
3.97
2.72
.491
.505
.516
79.2
5,584
3.42
3.94
2.69
.482
.496
.507
23..
70.5
61.1
4,308
2.53
3.27
2.02
.469
.487
.501
(5)
2.46
3.17
1.92
Average of periods "standing, relaxed" as shown in table 10, p. 71.
2Average of results with this subject from Dec. 7, 1911 to Apr. 16, 1912. (See table 91, Bene-
dict and Cathcart, Carnegie Inst. Wash. Pub. 187, 1913, p. 78.)
3Determined during four periods of an experiment on Apr. 18, 1914, the subject being without
food.
^Probably at the rate of about 57 meters per minute.
8Probably at the rate of about 61 meters per minute.
84
ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
TABLE 14 — Increase in heat-output during walking in experiments with subject II
without food — Continued.
(a)
(b)
(c)
(d)
Heat-output (computed).
/r\
Increase per kilogram-
Date and condi-
tions of experi-
ments.
Body-
weight
with
cloth-
ing.
Dis-
tance
per
minute.
Horizon-
tal kilo-
gram-
meters
(oXb).
Raising
of body
per
minute.
Total
per
minute.
\J )
Increase
above
standing
relaxed.
meter (gram-calorie).
(a)
Above
standing
relaxed
(h)
Above
lying,
O)
Above
lying,
(f+c).
I.
II.
1914
Walking —
Continued;
kilos.
meters.
meters.
cols.
cals.
gm.-cal.
gm.-cal.
gm.-cal.
Apr. 24 . .
70.5
76.4
5,386
3.60
3.79
2.54
.472
.486
.498
78.4
5,527
3.69
3.94
2.69
.487
.501
.512
25. .
69.9
63.0
4,404
2.65
3.21
1.96
.445
.463
.477
64.0
4,474
2.69
3.30
2.05
.458
.476
.489
27. .
70.5
73.5
5,182
3.25
3.77
2.52
.486
.502
.513
78.1
5,506
3.64
3.97
2.72
.494
.509
.519
28. .
70.5
78.2
5,513
3.41
4.04
2.79
.506
.521
.531
79.8
5,626
3.60
3.99
2.74
.487
.501
.512
80.0
5,640
3.53
4.06
2.81
.498
.512
.523
80.7
5,689
3.80
4.12
2.87
.504
.519
.529
80.4
5,668
3.33
4.40
3.15
.556
.570
.580
80.2
5,654
3.67
4.07
2.82
.499
.513
.524
80.2
5,654
3.80
4.14
2.89
.511
.525
.536
80.4
5,668
3.46
4.09
2.84
.501
.515
.526
May 13..
71.5
82.6
5,906
3.76
4.13
2.88
.488
.501
.511
89.7
6,414
4.51
4.50
3.25
.507
.519
.529
80.1
5,727
3.29
3.94
2.69
.470
.484
.494
76.6
5,477
2.84
3.75
2.50
.456
.471
.482
93.3
6,671
5.25
4.72
3.47
.520
.532
.541
91.9
6,571
5.15
4.67
3.42
.520
.533
.542
4. .
71.7
114.5
8,210
6.43
6.71
5.46
.665
.675
.682
109.1
7,823
6.16
5.79
4.54
.580
.591
.598
102.0
7,313
5.88
5.42
4.17
.570
.581
.589
5..
71.7
106.0
7,601
4.86
5.54
4.29
.564
.575
.583
102.6
7,356
5.82
5.33
4.08
. 555
.566
.574
103.6
7,428
6.06
5.51
4.26
.574
.584
.592
6. .
71.7
140.7
10,088
9.76
10.23
8.98
.890
.898
.904
139.6
10,009
8.90
10.38
9.13
.912
.920
.926
142.9
10,246
8.79
10.91
9.66
.943
.951
.956
10..
72.3
145.5
10,519
5.37
10.99
9.74
.926
.934
.939
146.8
10,613
5.81
11.68
10.43
.983
.990
.996
146.6
10,598
8.02
11.00
9.75
.920
.928
.933
Running:
May 11. .
72.0
146.6
10,554
13.45
9.47
8.22
.779
.786
.792
146.7
10,562
13.89
9.57
8.32
.788
.795
.801
148.3
10,677
14.80
9.69
8.44
.790
.798
.804
12. .
72.0
147.1
10,591
15.40
10.80
9.55
.902
.909
.915
148.4
10,684
14.09
9.19
7.94
.743
.751
.756
148.1
10,663
15.40
9.80
8.55
.802
.809
.815
148.1
10,663
14.74
9.97
8.72
.818
.825
.831
148.7
10,706
15.37
10.06
8.81
.823
.830
.836
Walking :
May 14. .
71.5
146.4
10,467
7.59
11.23
9.98
.953
.961
.967
Running :
May 14
146.5
10,474
15.44
11.13
9.88
.943
.951
.957
147.2
10,524
12.47
9.15
7.90
.751
.758
.764
147.6
10,553
12.34
9.26
8.01
.759
.767
.772
148.1
10,588
11.09
9.66
8.41
.794
.802
.808
15..
71.0
144.7
10,273
12.48
9.64
8.39
.817
.824
.830
148.4
10,536
12.14
9.67
8.42
.799
.807
.812
147.7
10,486
13.13
9.47
8.22
.784
.792
.797
DISCUSSION OF RESULTS. 85
In two of the walking experiments without food, those of April 6
and 7, we were able to obtain electrocardiograms of the pulse of this
sub j ect and the results are recorded in table 4 (pp. 54 and 55) . In previous
researches a striking uniformity has been found in the changes of the
metabolism and the pulse-rate, amounting at times to a distinct
percentage relationship between them. Such a uniformity was noted
by Benedict and Cathcart in their study of a bicycle rider when the
metabolism and pulse-rate during riding were compared with the
values obtained in the lying or sitting position. In this research, on
the contrary, the pulse-rate in the experiments of April 6 and 7 showed
a distinct lowering when the subject changed from the standing posi-
tion to walking, particularly in the experiment on April 7, notwith-
standing the fact that the total metabolism during walking increased
from 100 to 200 per cent above the basal metabolism of standing.
This lowering of the pulse-rate was so positive that it is difficult to
believe that any error was made in the measurements. Furthermore,
in the fourth period of the experiment on April 7, we find that the pulse-
rate with the subject standing after walking increased materially over
that during walking. The evidence thus implies that when standing
still upon the treadmill, this subject had a much higher pulse-rate than
when he was walking at a slow speed. These records are entirely
contrary to our previous experience but the lowered pulse-rate during
walking has been confirmed by Professor H. Monmouth Smith, of the
Laboratory staff, in similar experiments with three other subjects, thus
establishing the fact. Further experimenting is now in progress and
the results will be incorporated in a subsequent report.
INFLUENCE OF VELOCITY.
On all days subsequent to May 4, with the single exception of May
13, the speed of walking exceeded 100 meters per minute. At this
higher speed there was a distinctly higher energy requirement per
horizontal kilogrammeter. Thus, we have six periods when the rate
of walking was from 102 to 114.5 meters per minute and averaged 106.3
meters per minute. At this speed the average heat-output per hori-
zontal kilogrammeter was 0.585 gram-calorie, a material increase over
0.493 gram-calorie, the average heat-output for the lower speed. A
further grouping of the experiments is permissible when the speed
ranged from 139.6 to 148.7 meters per minute, as with this higher
speed a considerable increase is shown in the heat requirement per unit
of work. Some of the experiments in this group show that when the
subject ran instead of walked, the heat-output per horizontal kilo-
grammeter was lowered, although the rate of progression was prac-
tically the same; accordingly we may not advantageously draw average
values. In the two walking experiments on May 6 and 10 the speed
averaged 143.7 meters per minute and the heat per horizontal kilo-
grammeter 0.929 gram-calorie. In the first period of the experiment
86 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
of May 14 the subject walked at the rate of 146.4 meters per minute,
with a heat-output of 0.953 gram-calorie per horizontal kilogrammeter.
In the four following periods the subject ran, although the speed
per minute was approximately the same as that in the walking period.
Nevertheless, the average heat-output per unit of work was materially
less, i. e., 0.812 gram-calorie.
It is thus apparent that the velocity had a very considerable influ-
ence upon the heat per unit of work when the subject was walking.
This confirms the earlier contention of Durig and his associates that the
heat required to move 1 kilogram 1 meter increases with the speed.
Furthermore, the method of progression, i. e., walking or running, had
likewise a very considerable influence on the heat per unit of work.
Both of these factors require subsequent elaboration.
COMPARISON OF THE HEAT PER UNIT OF WORK AS COMPUTED FROM DIFFERENT BASE-LINES.
The last three columns of table 14 permit the comparison of the heat
per unit of work, i. e., per horizontal kilogrammeter, as computed
from the three base-lines. Instead of using the individual values hi
table 14, however, this comparison can better be made by using only
the average figures for the several groups presented in the foregoing
discussion on the influence of velocity. To find exactly the differ-
ences due to the selection of the base-line, we have therefore brought
together in table 15 a general average for all of the experiments without
food, both walking and running. The walking experiments are
divided into three groups, according to the speed at which the subject
walked. Thus we have 57 periods when the subject walked at a slow
rate ranging from 56 to 93.3 meters and averaging 71.5 meters, 6 periods
with a medium speed averaging 106.3 meters per minute, and 7 periods
with a high speed averaging 144.1 meters per minute. During the
running experiments, the speed averaged 147.5 meters per minute.
The values showing the heat-output per unit of work done, using the
Benedict and Cathcart basal value (lying I), are given in column 6,
those for which the basal value of April 18, 1914, was employed (lying II)
in column c, and those calculated from the basal value found with the
subject standing in the relaxed position are given in column d.
With the large amounts of heat involved in the walking experiments
the relatively slight differences appearing in these three base-lines
should not have a very great effect. It is obvious, moreover, that the
greater the amount of work done in walking, the less will be the per-
centage change due to the selection of the base-line. Thus we note that
the heat per unit of work done at the slow speed is lower when the
standing basal value is employed than it is when the lying value II
(that of April 18, 1914) is used, the difference between the two averages
being approximately 6 per cent. With the increase in the work
involved in walking at the moderate speed, the difference due to the
selection of the basal value becomes considerably less, i. e., 3 per cent,
DISCUSSION OF RESULTS.
87
and finally with the large heat production incidental to walking at the
rate of 144.1 meters per minute, the difference between the calculations
with the two base-lines becomes approximately only 1.5 per cent. This
small difference likewise holds in the running experiments. The values
computed from the Benedict and Cathcart base-line show the same
general characteristics, although the difference between the two results
is smaller than with the basal value of April 18, 1914.
It thus appears that as the total amount of work increases it becomes
less important which of the three base-lines is used. For slow and
moderate speeds a possible difference of 3 to 6 per cent in the average
value of the heat per unit of work may be expected, while with the
highest speed this difference decreases to from 1 to 1.5 per cent. The
TABLE 15.-
-Comparison of heat-output during walking and running as referred to basal values
for the lying and standing positions.
[Experiments with subject II without food.]
Heat (computed) per hori-
Average
zontal kilogrammeter
distance
(gram-calorie).
Number of
per
|
periods.
minute
(meters)
Above
lying I1
Above
lying II1
Above
standing
relaxed1
(a)
(b)
(c)
W
Walking :
57
71 5
0.509
0.521
0.493
6
106 3
.595
.603
.585
7
144.1
.940
.946
.932
Running:
15
147.5
.814
.819
.806
table 14, p. 83, for explanation of basal values used.
importance of the selection of a basal value is therefore greatest when
the amount of walking to be performed is smallest, i. e., when the sub-
ject is walking at moderate speed. This is somewhat unfortunate, for
a large proportion of walking for exercise, for the carrying of burdens,
and in marching is usually done at a moderate speed. Since, however,
the basal values obtained with the subject standing in the relaxed
position were daily and accurately determined, and since there is such
a high degree of constancy in the standing relaxed values, we consider
that they may be properly used as the basal values for these compu-
tations. The figures obtained per unit of work on this basis may there-
fore be considered to represent the increased metabolism necessary to
move 1 kilogram 1 meter in a horizontal direction.
EXPERIMENTS WITH FOOD.
A large number of experiments following the ingestion of food were
made with subject II. The results of all these experiments are pre-
sented in table 16, the data being grouped arbitrarily according to the
preceding meal and especially according to the character of the diet.
88
ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
TABLE 16. — Increase in heat-output during walking in experiments with subject II
with food.
Diet and date.
Condition.
(a)
Body-
weight
with
cloth-
ing.
(6)
Dis-
tance
per
minute.
(c)
Horizon-
tal kilo-
gram-
meters
(aXb).
(d)
Raising
of body
per
minute.
Heat-output (computed).
(e)
Total
per
minute.
Increase over
standing.
(/)
Total.
(ff)
Per
horizon-
tal kilo-
gram-
meter
(/-5-c).
1914
Breakfast.
Not controlled:
Mar. 16. .
18
Standing1.
kilos.
meters.
meters.
2.88
3.34
3.62
3.16
3.11
2.74
2.61
2.52
2.26
1.91
1.98
1.87
3.63
3.56
3.52
3.74
3.76
3.29
3.73
3.69
3.17
3.75
3.55
2.39
2.59
.81
1.50
2.30
2.15
2.12
2.40
2.24
1.72
2.02
2.84
3.38
2.05
2.21
cah.
'1.43
3.92
4.06
4.09
4.21
3.74
3.40
3.74
3.48
3.65
3.23
3.07
3.24
21.59
4.31
4.26
4.20
4.07
4.09
3.87
4.10
3.98
31.55
3.99
4.02
4.09
3.16
3.40
3.99
3.64
3.67
3.62
3.81
3.59
3.53
3.53
3.44
4.68
4.47
3.51
3.74
cals.
2.49
2.63
2.66
2.78
2.31
1.97
2.31
2.05
2.22
1.80
1.64
1.81
gm.-cal.
0.463
.478
.471
.513
.551
.470
.555
.479
.527
.454
.401
.447
Walking . . .
do
72.4
72.4
72.4
72.4
72.4
72.0
72.0
72.0
74.3
76.0
78.0
74.9
57.9
57.9
57.5
59.4
58.5
55.1
56.8
56.2
5,379
5,502
5,647
5,423
4,192
4,192
4,163
4,277
4,212
3,967
4,090
4,046
19
do . ...
21
do. .
23
do.
28.
do
30
do
Apr. 4
. . do.
Controlled :
Carbohydrate :
Apr. 29 . .
Lunch.
Not controlled:
Mar. 16. .
18..
19
Standing2. .
Walking . . .
Standing3. .
70.9
76.9
78.2
79.5
80.9
81.1
80.9
81.0
81.1
5,452
5,544
5,637
5,736
5,750
5,736
5,743
5,750
2.72
2.67
2.61
2.48
2.50
2.28
2.51
2.39
.499
.482
.463
.432
.435
.397
.437
.416
Walking . . .
.... do
do.
72.4
72.4
72.4
72.4
72.4
72.0
72.0
72.0
72.0
72.0
72.0
72.0
72.0
72.0
75.3
76.3
74.9
52.7
52.8
62.7
61.1
60.7
58.6
59.3
58.5
57.3
57.7
57.0
77.0
78.9
54.4
58.1
5,452
5,524
5,423
3,815
3,823
4,514
4,399
4,370
4,219
4,270
4,212
4,126
4,154
4,104
5,544
5,681
3,917
4,183
2.44
2.47
2.54
1.61
1.85
2.44
2.09
2.12
2.07
2.26
2.04
1.98
1.98
1.89
3.13
2.92
1.96
2.19
.448
.447
.468
.422
.484
.541
.475
.485
.491
.529
.484
.480
.477
.461
.565
.514
.500
.524
20
do.
21.
do
24
... do
25
. . do . .
26
do.
27
do.
28
do.
30
do.
31. .
do
Apr. 3. .
do. . . .
4. .
do.. ..
^Average of all periods with subject standing after a light meal (breakfast). See table 11, p. 72.
2Standing, relaxed. Average of values obtained with similar diet on Apr. 25 and Apr. 27. See
table 12, p. 74.
3Average of results obtained for all positions standing after lunch, diet not controlled. See
table 12, p. 74.
DISCUSSION OF RESULTS.
89
TABLE 16. — Increase in heat-output during walking in experiments with subject II
with food — Continued.
Diet and date.
Condition.
(a)
Body-
weight
with
cloth-
ing.
(6)
Dis-
tance
per
minute
(c)
Horizon-
tal kilo-
gram-
meters
(0X6).
(d)
Raising
of body
per
minute
Heat-output (computed).
(e)
Total
per
minute
Increase over
standing.
(/)
Total.
(0)
Per
horizon-
tal kilo-
gram-
meter
(/-c).
1914
Lunch — Cont'd.
Controlled :
Protein :
Apr. 6 . .
7. .
8. .
23. .
24. .
May 5. .
May 10. .
Carbohydrate:
Apr. 9 . .
Apr. 10. .
14. .
15. .
Standing . .
kilos.
meters.
meters.
2.21
1.94
1.81
1.78
1.83
1.82
2.50
3.01
2.70
2.74
2.57
2.48
2.63
3.74
3.88
3.84
3.88
7.69
7.83
6.40
7.76
7.83
8.28
1.95
1.94
1.94
3.01
3.17
3.35
2.38
2.20
2.27
3.88
3.72
3.88
cals.
1.43
3.54
3.51
3.46
1.37
3.59
3.77
3.41
1.33
4.28
4.38
4.46
1.24
3.55
3.44
3.45
3.45
1.41
4.05
4.11
4.26
4.24
11.36
6.34
6.43
5.89
6.31
4.36
11.05
11.07
1.43
3.48
3.43
3.53
1.47
4.70
4.59
4.37
1.42
3.40
3.54
3.47
1.38
4.52
4.41
4.63
cals.
gm.-cal.
Walking . . .
Standing
72.0
57.5
57.2
56.3
4,140
4,118
4,054
2.11
2.08
2.03
2.22
2.40
2.04
2.95
3.05
3.13
2.31
2.20
2.21
2.21
2.64
2.70
2.85
2.83
4.98
5.07
4.53
4.95
.510
.505
.501
.524
.568
.498
.533
.543
.549
.535
.507
.509
.508
.486
.486
.505
.502
.617
.622
.596
.620
Walking . . .
Standing .
72.0
58.8
58.7
56.9
4,234
4,226
4,097
Walking . . .
Standing . .
72.0
76.9
78.0
79.2
5,536
5,616
5,702
Walking . . .
Standing . .
70.5
61.2
61.6
61.6
61.7
4,315
4,343
4,343
4,350
Walking . . .
Standing1.
70.5
77.0
78.8
80.0
80.0
5,428
5,555
5,640
5,640
Walking . . .
Standing1.
71.7
112.6
113.7
106.0
111.3
8,073
8,152
7,600
7,980
Walking . . .
Standing . .
72.3
146.5
146.9
10,592
10,621
9.69
9.71
.915
.914
Walking . . .
Standing . .
Walking . . .
Standing
72.0
72.0
59.4
59.0
58.8
78.0
79.1
79.7
4,277
4,248
4,234
2.05
2.00
2.10
.479
.471
.496
5,616
5,695
5,738
3.23
3.12
2.90
.575
.548
.505
Walking . . .
Standing . .
71.9
61.2
62.0
62.2
4,400
4,458
4,472
1.98
2.12
2.05
.450
.476
.458
Walking . . .
71.5
78.2
80.1
80.6
5,591
5,727
5,763
3.14
3.03
3.25
.562
.529
.564
Standing, relaxed; average obtained on 5 days with protein diet (table 12).
90
ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
TABLE 16. — Increase in heat-output during walking in experiments with subject II
with food — Continued.
(a)
(6)
(c)
(d)
Heat-output (computed) .
Increase over
standing.
Diet and date.
Condition.
Body-
weight
with
Dis-
tance
Horizon-
tal kilo-
gram-
Raising
of body
(e)
Total
(/)
(9)
Per
cloth-
ing.
per
minute.
meters
(0X6).
per
minute.
per
minute.
Total.
horizon-
tal kilo-
gram-
meter
1914
Lunch — Cont'd.
Carbohydrate —
cont'd.
kilos.
meters.
meters.
cals.
cals.
gm.-cal.
Apr. 25 . .
Standing
1.58
Walking . . .
69.9
63.1
4,411
2.88
3.52
1.94
.440
63.8
4,460
2.70
3.53
1.95
.437
63.7
4,453
2.85
3.49
1.91
.429
63.3
4,425
2.64
3.34
1.76
.398
27. .
Standing
1.61
Walking . . .
70.5
77.5
5,464
3.60
4.30
2.69
.492
....
78.9
5,562
3.56
4.02
2.41
.433
....
79.8
5,626
3.88
4.24
2.63
.467
80.2
5,654
3.74
4.04
2.43
.430
Mav 4
Standing1
lj gg
iv JL C*^ ^ . .
Walking . . .
71.7
113.4
8,131
6.84
6.59
5.00
.615
....
112.3
8,052
7.88
6.46
4.87
.605
110.3
7,909
7.41
6.10
4.51
.570
6. .
Standing1. .
H.59
Walking . . .
71.7
143.0
10,253
7.82
10.73
9.14
.891
11. .
Standing1
^.59
Running. . .
72.0
148.7
10,706
13.95
9.50
7.91
.739
Fat:
Apr. 16 . .
Standing
1.41
Walking . . .
71.5
61.6
4,405
2.49
3.35
1.94
.440
62.3
4,455
2.48
3.15
1.74
.391
62.2
4,447
2.24
3.43
2.02
.454
61.9
4,426
2.21
3.42
2.01
.454
17. .
Standing
1.36
Walking . . .
71.5
77.6
5,548
3.96
4.06
2.70
.487
....
79.5
5,684
3.78
4.27
2.91
.512
....
80.0
5,720
3.85
4.56
3.20
.559
80.0
5,720
3.67
4.15
2.79
.488
21. .
Standin^
1.42
Walking . . .
70.5
60.4
4,258
2.45
3.33
1.91
.449
....
60.6
4,272
2.56
3.43
2.01
.471
60.5
4,265
2.34
3.44
2.02
.474
60.5
4,265
2.23
3.43
2.01
.471
22. .
Standin"
1.42
Walking . . .
70.5
77.3
5,450
3.86
4.07
2.65
.486
78.7
5,548
3.86
4.24
2.82
.508
....
79.5
5,604
3.92
4.25
2.83
.505
....
79.7
5,619
3.84
4.18
2.76
.491
Standing, relaxed.
See table 12, p. 74.
Average of values obtained with similar diet on Apr. 25 and Apr. 27.
DISCUSSION OF RESULTS. 91
As we have already seen from the discussion in an earlier section,1
the metabolism in the standing relaxed position after the ingestion of
food was considerably greater than that obtained when the subject was
without food, this being due to the katabolic stimuli of the foodstuffs.
Of most importance, however, is the question whether the increment due
to walking is superimposed upon the increased katabolism due to food
or whether this increment is lessened by the fact that the body is
previously stimulated to a greater katabolic activity. With a view to
studying the influence of variations in the intensity of the pre-walking
stimulation, certain of the diets were so controlled as to consist in
large part of one of the three principal food constituents, i. e., protein,
fat, or carbohydrate. With the experimental conditions and the impos-
sibility of controlling the subject's diet while he was outside of the
laboratory, it was impracticable to make a thorough study of this par-
ticular phase of the problem. Our data do not therefore present a
conclusive statement as to the influence of the special protein, fat, or
carbohydrate diets, but merely contribute to the interesting question
as to whether or not the increase in the katabolism following the inges-
tion of food persists during increased muscular activity or if there be a
summation effect under these conditions.
Since we have seen not only from the work of previous investigators,
but from tables 14 and 15, that there is a marked influence upon the
heat per unit of work as the result of an increase in velocity, particu-
larly when the velocity is above 95 meters per minute, it seems prefer-
able to consider the data presented in table 16 from this point of view.
As in the experiments with this subject when no food was taken, here
again we find that in the greater number of the experiments the speed
varied from 52.7 to 81.1 meters per minute, there being but 7 periods at
speeds ranging from 106 to 113.7 meters per minute, and but 4 periods
with a speed over 140 meters per minute.
Considering first the experiments at the lower speed, we find that
91 periods are available for study. The average velocity during these
periods was 68.2 meters per minute and the heat per unit of work done,
i. e., per horizontal kilogrammeter, was 0.486 gram-calorie. It will be
seen from the table that the standing basal value for the total heat-
output per minute in the experiments with food ranged from 1.24 to
1.61 calories per minute, averaging considerably above those obtained
when the subject was standing in the post-absorptive condition. On
the other hand, since the average value per unit of work done in 57
periods without food was 0.493 gram-calorie and the average of 91
periods with food was 0.486 gram-calorie, it is clear that the increase
over the basal metabolism was the same in both instances; in other
words, the increment due to the work of forward progression was
lSee p. 75.
92 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
constant, irrespective of whether the subject was with or without food,
this being true for subject II with the rate of speed varying from 52.7
to 93.3 meters per minute.
At moderate speeds above 100, we have seven periods with food in
which the velocity varied from 106 to 113.7 meters per minute, the
average speed being 1 1 1 .4 meters per minute, and the average output of
heat per unit of work done 0.606 gram-calorie. Certain difficulties
appear when an attempt is made to compare the results of these
periods with food with periods without food. First, the speed per
minute without food was 106.3 meters and that with food 111.4 meters,
this being a perceptible increase. Second, but few periods are available
for comparison either with or without food, there being but 7 for the
former and 6 for the latter. If we make such a comparison, however,
we find that with food the heat per unit of work is 0.606 gram-calorie,
while that without food was only 0.585 gram-calorie. It is probably
not possible to attribute this increase in the heat-output per unit of
work solely to the increase of 5 per cent in the speed, and we can only
state that with speeds averaging 111.4 meters per minute the increase
in the heat per horizontal kilogrammeter with food is perceptibly
greater than that with food at a speed of 68.2 meters per minute.
The comparison becomes even more difficult when we consider the
experiments with the highest speeds, namely, those of 140 meters per
minute and over. Here we have but 4 periods with food, with the
speed ranging from 143 to 148.7 meters per minute and an average
speed of 146.3 meters per minute. The comparison is still further
complicated by the fact that in one of these four periods the subject
was running. The average heat-output per unit of work done for the
three walking periods was 0.907 gram-calorie and the value found for
the one period with the subject running was 0.739 gram-calorie, a
value much less than that obtained with the subject walking.
We may thus say that all of the observations made after the taking
of food are completely in accord with those made when no food was
taken, i. e., an increase in the energy per unit of work done as the speed
increased and a considerably less energy per unit of work done when
the subject was running as compared with that when he was walking.
An analysis of the processes of running and walking and the character
of the steps is necessary to interpret these differences intelligently.1
Electrocardiograms of the pulse-rate were obtained in a few of the
experiments following the ingestion of food, namely, those of April 4,
6, and 7.2 These records show the same discrepancy between the pulse-
rate and the metabolism as was found in the experiments without food.3
'See p. 98. 2See table 4, pp. 54 and 55. 3See p. 85.
DISCUSSION OF RESULTS.
93
INFLUENCE OF THE CHARACTER OF DIET ON THE HEAT-OUTPUT PER UNIT
OF WORK.
While from the general observations of the metabolism with and
without food the inference was properly drawn that there was no
material increase in the heat-output per unit of work in the food
periods, nevertheless certain of the experiments permit a more detailed
examination of this point since a reasonably satisfactory grouping of
the results may be made upon the basis of the character of the diet.
The experimental plan as originally outlined called for a series of
walking experiments at each of the three standard speeds with diets
containing a preponderance of each of the three principal nutrients.
The average figures representing the heat per unit of work with the
three diets and the three speeds are collected in table 17. In this table
the average speed for the different groups is given, as the speed per
minute, especially with the low speed, was not exactly the same for the
three diets. Only the walking experiments are considered in this
connection, none of the running experiments being included.
TABLE 17 — Influen:
~4 character of diet on the heat-output per horizontal kilogrammeter during
walking experiments with subject II.
Character of diet.
Low speed.
Moderate speed.
High speed.
Meters.
Gm.-cal.
Meters.
Gm.-cal.
Meters.
Gm.-cal.
Carbohydrate .
73.2
67.1
70.1
0.471
.516
.478
112.0
110.9
0.597
.614
143.0
146.7
0.891
.915
Protein
Fat
Aside from the generally increasing value of the heat per unit of
work as the speed increases, which is clearly shown in table 17, we
note, in comparing the values obtained with the different diets, a dis-
tinctly higher, although not striking, increase in the heat per unit of
work with the protein diet as compared with the carbohydrate diet,
this increase being approximately 9 per cent at the low speed and 3 per
cent at the moderate and high speeds. With the fat diet the com-
parison was made only with the low speed, and we find that the heat-
output per unit of work was essentially the same as that with the car-
bohydrate diet and measurably less than was obtained with the protein
diet. The general impression derived from the comparison of all the
experiments with subjects I and II was that the heat per unit of work
was practically independent of the taking of food. It appears from the
foregoing discussion, however, that this conclusion should be slightly
modified when diets containing large quantities of protein are con-
sidered, for the data in table 17 indicate that with such a diet a slightly
higher heat-output per unit of work may be expected.
94 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
INFLUENCE OF FATIGUE UPON THE HEAT-OUTPUT PER UNIT OF WORK.
Many of our experiments were made with a sufficient number of con-
secutive walking periods to permit a study of the heat per unit of work
done under conditions of accumulated work. The average length of
the walking period was 14 minutes. The distance traveled in a period
in the prolonged walking experiments varied from 800 to 1,200 meters,
and the subject walked not only during the experimental periods, when
the gaseous metabolism was being measured, but also between these
periods. When, therefore, the experiment consisted of four or more
experimental periods, it will be seen that the continuous walking would
amount frequently to several kilometers, thus providing conditions for
studying the effect of fatigue. In relatively few of these experiments,
however, was there substantial evidence of extreme fatigue.
The results of the observations in which there were four or more
periods of continuous walking are brought together in table 18. The
data given show the total distance walked by the subject prior to the
beginning of each experimental period1 and both the distance walked
per minute and the heat-output per unit of work performed during the
period. On two days, April 28 and 29, 1914, there were eight walking
periods; the total distance traversed each day in continuous walking
was approximately 23 kilometers. Throughout both experiments the
distance per minute remained essentially constant at about 80 meters;
we thus have ideal conditions for studying the influence of fatigue
resulting from continuous walking. On April 28, when the subject was
without food, there was no essential difference in the unit of work done
as the experiment progressed, although there were variations from
period to period. On the next day, a similar experiment was made
after food had been taken. The average heat per unit of work done
on this day was considerably less than that on April 28 and a general
tendency was also shown for the heat per unit of work done to decrease
as the work progressed. Inspection of the values found for another
experiment of 6 periods on May 13, when the subject was without food,
shows more or less fluctuation in the values obtained for the heat per
unit of work done, but there is no uniformity in the changes and,
indeed, the values are somewhat greater in the last periods than in the
earlier periods. With the experiments having only four periods, in
which the total distance walked prior to the last period ranged from
8 to 12 kilometers, we find that on certain days there was a tendency
for the heat per unit of work to decrease as the walking progressed and
on other days to increase, but in the majority of the experiments there
was no regularity in the variations.
From the data given in table 18, we may conclude that there may be
noticeable differences in the absolute heat per unit of work done on
different days, a point particularly brought out in the experiments of
'For total distance walked, see table 4, pp. 56 to 60.
DISCUSSION OF RESULTS.
95
April 28 and April 29. Nevertheless, there is no definitely uniform
influence of prolonged walking upon the efficiency for horizontal
movement shown by this subject and the heat per unit of work after he
had walked 20 kilometers is as liable to be lower than the initial value
as it is to be higher. In other words, in this series of experiments, the
measured metabolism agrees perfectly with the subjective impression
that there was not a sufficient degree of fatigue to affect the comfort
TABLE 18. — Heat-output per unit of work during prolonged walking in experiments with subject II .
Distance walked.
Heat
(com-
Distance walked.
Heat
(com-
puted)
puted)
Date.
Total to
beginning
of period.1
Per
minute
during
period.
per hori-
zontal
kilo-
gram-
meter.2
Date.
Total to
beginning
of period.1
Per
minute
during
period.
per hori-
zontal
kilo-
gram-
meter.2
1914
1914
Without food :
meters.
meters.
gm.-cal.
With food :
meters.
meters.
gm .-cat.
Apr. 28 ...
382
78.2
0.506
Apr. 29. .
650
76.9
0.499
3,322
79.8
.487
3,519
78.2
.482
6,316
80.0
.498
6,585
79.5
.463
9,538
80.7
.504
9,699
80.9
.432
13,062
80.4
.556
12,615
81.1
.435
16,416
80.2
.499
15,547
80.9
.397
19,033
80.2
.511
18,662
81.0
.437
22,479
80.4
.501
21,676
81.1
.416
May 13. ..
521
82.6
.488
Apr. 22 . .
368
77.3
.486
3,993
89.7
.507
3,452
78.7
.508
7,737
80.1
.470
7,067
79.5
.505
11,391
76.6
.456
10,345
79.7
.491
16,413
93.3
.520
Apr. 23 . .
348
61.2
.535
20,527
91.9
.520
2,723
61.6
.507
With food :
5,512
61.6
.509
Apr. 16. ..
303
61.6
.440
7,976
61.7
.508
2,557
62.3
.391
Apr. 24. .
354
77.0
.486
5,901
62.2
.454
2,879
78.8
.486
9,424
61.9
.454
5,541
80.0
.505
Apr. 17. ..
507
77.6
.487
8,295
80.0
.502
3,945
79.5
.512
Apr. 25 . .
323
63.1
.440
7,572
80.0
.559
2,330
63.8
.437
12,266
80.0
.488
5,122
63.7
.429
Apr. 21...
307
60.4
.449
8,125
63.3
.398
2,658
60.6
.471
Apr. 27..
372
77.5
.492
5,374
60.5
.474
2,905
78.9
.433
8,515
60.5
.471
5,693
79.8
.467
9,366
80.2
.430
xFor total distance walked, see table 4, pp. 56 to 60.
2Calculated for each period from the increment above values obtained with the subject standing
relaxed. See tables 14 and 16, pp. 83 and 88.
of the subject or his metabolism and that at the' speed used throughout
these tests, namely, 80 meters per minute, walking may be done for
many kilometers without affecting the efficiency of the body for loco-
motion in a forward direction.
The stamina of the subject and his capacity for excessive work was
severely tested in the earlier research on prolonged bicycle riding, in
96 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
which it was demonstrated that this subject had ridden the equivalent of
100 miles over average roads on an empty stomach; but in this research
it was impracticable to carry out prolonged endurance tests at high
rates of speed. Indeed, at the highest speed, i. e., 140 kilometers per
minute, it is very certain that the subject would have run instead of
walked, as distances as great as 20 or more kilometers are rarely covered
rapidly by walking, but usually by running. On the other hand, a
speed of 80 meters per minute represents an average rapidity of motion
when long-distance walking is to be done and hence the values obtained
at this speed have a much greater practical use than would values
secured with the subject walking at a higher speed.
COMPARISON OF THE HEAT-OUTPUT PER UNIT OF WORK DURING RUNNING
WITH THAT OBTAINED DURING WALKING.
The striking difference between the heat per unit of work observed
when the subject was running and that obtained when he was walking
has already been noted in table 15 (see p. 87), the figures showing that
considerably less energy per unit of work was required for moving the
body forward in running than in walking under the experimental
conditions. The values obtained when the subject was moving
forward at the rate of approximately 144 meters per minute give the
only data for a direct comparison, no running experiments being made
at the lower rates of walking. At this speed, the value computed for
walking (using the standing basal value) is 0.932 gram-calorie and for
running 0.806 gram-calorie. That these are not accidental figures
is shown by the fact that the first value is the average of 7 reasonably
agreeing periods and the second value is the average of 15 well agreeing
periods; in other words, we deal here with a positive difference of
approximately 15 per cent. It thus becomes important to analyze,
if possible, the mechanical movements incidental to walking, and par-
ticularly rapid walking, to find the reason for this discrepancy.
Traveling at the speed of 144 meters per minute, the ordinary
individual without load generally runs rather than walks. On the
other hand, in transporting heavy material as, for example, military
accouterments and trappings, running would be wholly impracticable
and walking must be resorted to. It has been noted, especially in
observations of professional walkers, that in rapid walking there is
commonly very great extraneous arm movement, the arms being
violently swung back and forth with each step. In the belief that this
unusual extraneous muscular movement results in a large energy
transformation which does not directly contribute to the forward pro-
gression, the study previously referred to was made in which the energy
requirement of subject II was observed while he stood and swung his
arms violently as in rapid walking. These values have already been
discussed in connection with the standing resting values,1 when it was
'See table 10 and p. 71.
DISCUSSION OF RESULTS.
97
found that in one experiment the heat-output per minute was 2.53
calories and in the other 3.13 calories per minute, or an average heat-
output of 2.83 calories per minute as compared with 1.25 calories per
minute, the average of the basal values obtained with the subject
standing relaxed. It will therefore be seen that when the arms were
swung violently, the metabolism was increased 126 per cent.
It is accordingly important for us to eliminate, if possible, the influ-
ence of this extraneous arm motion. To this end we have computed in
table 19 the heat-output per unit of work during rapid walking, using
TABLE 19. — Increase in heat-output during fast walking in experiments with subject II.
[Basal value, standing swinging arms.1]
Heat-output (computed).
Date.
Body-
weight
m4-l*
Distance
per
Total
Increase due to walking.
witn
clothing.
minute.
per
minute.
Total.
Per horizontal
kilograrnmeter.
1914
Without food :
kilos.
meters.
cols.
cals.
gm.-cal.
May 6 ....
71.7
140.7
10.23
7.40
0.734
139.6
10.38
7.55
.754
142.9
10.91
8.08
.789
10
72.3
145.5
10.99
8.16
.776
146.8
11.68
8.85
.834
146.6
11.00
8.17
.771
14
71.5
146.4
11.23
8.40
.803
Average
780
With food :
|
Protein —
May 10 ....
72.3
146.5
11.05
8.11
.766
146.9
11.07
8.13
.765
Carbohydrate —
May 6 ....
71.7
143.0
10.73
7.56
.737
Average
.756
'The subject stood without food swinging his arms violently as in the most rapid walking.
(See table 10, p. 71.) In computing the results for walking without food, the average value
(2.83 cals.) is used; for walking with food the increment (2.83 — 1.25=1.58 cals.) due to swinging
the arms is added to the value obtained for "standing, relaxed" with the respective diets.
2.83 calories as the base-line, i. e., the average value found with the
subject standing and swinging his arms violently. Under these condi-
tions we find a marked depression in the heat-output per unit of work as
compared with that computed with a base-line obtained with the sub-
ject standing in a relaxed position. In the experiments without food,
this averaged with the high speeds, 0.932 gram-calorie,1 but with the
new basal value, it averages 0.780 gram-calorie. This value compares
favorably with the value of 0.806 gram-calorie1 found in the 15 periods
with the subject running, being some 3 per cent less.
'See table 15, p. 87.
98 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING.
In the experiments with food there is likewise a great decrease in the
heat production per unit of work when this new base-line is used.
Averaging the result of one period of fast walking after food on May 6
and those of the two periods on May 10, we find that the heat per unit
of work is 0.756 gram-calorie as compared with 0.907 gram-calorie,1
which is the average heat-output per unit of work as computed with the
basal value found with the subject standing relaxed. The average
of 0.756 gram-calorie agrees very closely with the value of 0.739 gram-
calorie found in the experiment of May 11, 1914, when the subject was
running after the taking of food.1
It would thus appear that the apparent disadvantage in walking a
given distance at a speed of approximately 144 meters per minute as
compared with running is due to the type of walking commonly
employed by professional pedestrians and used by subject II, the extra-
neous movements of the arm playing an important role.
ANALYSIS OF THE MECHANICS OF LOCOMOTION.
The experimental data obtained in this research permit the compari-
son of several important factors in the mechanics of locomotion as we
have accurate records of the distance walked per minute, the number
of steps per minute and the height to which the body was raised per
TABLE 20. — Mechanics of locomotion in walking experiments with subject II.
Speed.
(a)
Average
raising of
body per
minute.
(b)
Average
distance
per
minute.
(c)
Average
number
of steps
per
minute.
(d)
Length
of step
(b + c).
(e)
Raising
of body
per
step
(o-5-c).
Walking :
Low
meters.
2 88
meters.
69 3
108.2
cm.
64 0
cm.
2.66
Medium
6.69
109.0
130.9
83.3
5.11
High
7.90
144.5
152.4
94.8
5.18
Running
13.76
147.6
181.9
81.1
7.56
minute. These values for the varying conditions of walking and run-
ning and with and without food appear in several of the preceding
tables2 and have been used as the basis for computing the values com-
pared in table 20. In this table the average values are given for the
height to which the body was raised both per minute and per step, the
distance walked or run per minute, the number of steps per minute, and
the length of the step. The comparisons are made for the values
obtained with the subject walking at low, medium, and high rates of
speed, and with the subject running, the rate of progression for the
latter being approximately the same as in walking at high speed.
JSee table 16.
2See tables 4, 13, 14, and 16.
DISCUSSION OF RESULTS. 99
At the low speed the subject walked 69.3 meters per minute, and took
108.2 steps per minute, the average length of the step being 64.0 cm.
With an increase in speed we note an increase not only in the number of
steps per minute, but likewise in the length of the step, the number
of steps per minute for the fast walking being 152.4 and the length of
the step 94.8 cm. When we consider the height to which the body was
raised, we find that the average height per minute was greatly increased
as the speed increased, that obtained at the medium rate being more
than twice the value secured with the low speed, i. e., an increase from
2.88 meters to 6.69 meters. When the average values obtained at the
medium and fast speeds are compared, we find that although the
average distance walked per minute increased from 109.0 meters to
144.5 meters and the number of steps taken per minute from 130.9
to 152.4, the increment in the distance over which the body was raised
was but 1.21 meters.
Of special interest in this connection is the extraordinary influence of
the change in locomotion from fast walking to running. The increase
in the speed was inconsiderable, being but 3.1 meters per minute. We
find, however, that in running the average height to which the body was
lifted increased from 7.90 meters to 13.76 meters per minute and the
average number of steps from 152.4 to 181.9 per minute, the latter
increment not being at all in proportion to the former. On the other
hand, the length of the step was decreased in running from 94.8 cm.
to 81.1 cm. It is thus apparent that in running the steps were taken
much more rapidly and considerably shortened and that the body was
raised to a much higher point at each step.
In any analysis of the mechanics of forward progression, therefore,
we should bear in mind the fact that in running the body is actually
lifted to nearly twice the height that it is raised during walking. This
would of itself involve mechanical work not directly contributory to the
work of forward progression and we should therefore expect to find, on
this basis alone, that the work of walking would be much more economi-
cally done than the work of running. On the other hand, it has been
pointed out in connection with the fast walking experiments that the
subjects involuntarily, or possibly as the result of previous training, did
an excessive amount of muscular work with the arms which likewise
was not contributory to the motion of forward progression. If, how-
ever, in comparing the values for the heat output per unit of work done
in walking and running, we use as a base-line the value obtained with
the subject standing and swinging his arms vigorously, we find that the
advantage still lies with the walking rather than with the running.
Thus, while the heat-output per unit of work with the subject running
without food is 0.806 gram-calorie with the standing relaxed base-line,
when we use the base-line obtained with the subject swinging his arms
the value becomes 0.780 gram-calorie for the 7 periods without food and
100 ENERGY TRANSFOEMATIONS DURING HORIZONTAL WALKING.
0.756 gram-calorie for the three periods with food, with an average
value of approximately 0.768 gram-calorie. While these experiments
are relatively few in number, it is quite possible that the apparent lower
value obtained for walking as compared with running, after deducting
the standing active base-line, may be explained by the fact that the
body is elevated nearly twice as much when running as when walking
and that to cover the same distance about 20 per cent more steps were
needed. In the motion of forward progression we have therefore to
take into account, first, the extraneous muscular activities not directly
contributory to the work of forward progression, chief among these
being the extraneous muscular movements of the arms in rapid walking
which require the expenditure of a considerable amount of energy.
Second, the type of step or the gait plays an important role, since in
raising the body work is performed, requiring an expenditure of energy.
When the body is raised approximately 14 meters per minute during
running, it may be readily computed that with a man weighing 70
kilograms, this would be equivalent to raising 980 kilograms one meter
in one minute corresponding to over 2.2 large calories. Any type of
locomotion, therefore, which minimizes the raising of the body is the
most economical. As a natural outcome of the study it will be seen
that it would be desirable for athletes and others interested in the work
of forward progression to develop a gait which will eliminate these two
apparently unnecessary and extraneous factors, each of which requires
the expenditure of a considerable amount of energy which is not
directly contributory to the motion of forward progression.
NUTRITION LABORATORY OF THE
CARNEGIE INSTITUTION OF WASHINGTON.
Boston, Massachusetts, June 19, 1915.
MBL/WHOI LIBRARY
UH IflGD 1
Live Music Archive
Librivox Free Audio
Metropolitan Museum
Cleveland Museum of Art
Internet Arcade
Console Living Room
Books to Borrow
Open Library
TV News
Understanding 9/11