108 
MUSCULAR WORK 
The earlier experiments with the form of bicycle ergometer in which an 
electric motor was attached to the rear wheel of the bicycle have been col- 
lected and summarized in a table by Atwater and Benedict. (See table 104.) 
In this table are given the average resting katabolism, the average working 
katabolism, the increased katabolism due to work, and the heat equivalent 
of the external muscular work, together with the net efficiency. To the 
original table we have added a column showing the gross efficiency. 
The disadvantages in the first ergometers used were very quickly recog- 
nized by these investigators, and plans for a new form of ergometer were 
immediately made. The later apparatus, which was as a matter of fact the 
"ergometer I " used in our study on muscular work, was employed by Benedict 
and Carpenter in an extensive series of investigations with several subjects. 6 
A series of six experiments during work was made with a well-trained college 
athlete, J. C. W., of which an abstract is given in table 105. 
Table 105. — Heat equivalent of muscular work and corrected amount of heat produced in 
experiments with J. C. W., as reported by Benedict and Carpenter. (7 a.m. to 7 p.m.) 
Experiment. 
Date. 
Heat equiv- 
alent of 
muscular 
work. 
Heat 
pro- 
duced. 
Heat pro- 
duced over 
resting 
metabolism. 
Net 
effi- 
ciency. 
No. 56 
No. 57 
1903. 
Apr. 27-28 
Apr. 28-29 
Apr. 29-30 
May 7-8 
May 8-9 
May 9-10 
cals. 
569 
601 
538 
657 
563 
587 
cals. 
3,959 
4,139 
3,834 
4,309 
4,056 
4,131 
cals. 
2,619 
2,799 
2,494 
2,969 
2,716 
2,791 
p. ct. 
21.7 
21.5 
21.6 
22.1 
20.7 
21.0 
As will be seen, the average net efficiency for this subject was 21.5 per 
cent. The computations in this table are based upon the fact that the work 
was all done between 7 a.m. to 7 p.m., and hence the energy required for rest 
experiments during the same period is deducted from the energy produced 
during the severe muscular work. The average of four rest experiments 
showed that from 7 a.m. to 7 p.m. this subject gave off on the average 1,340 
calories, the range being from 1,320 to 1,383 calories. 
The comparison as made is subject to a correction for the extra heat pro- 
duction incidental to the ingestion of food. Larger diets were taken on the 
work days than on the rest days, and as Oppenheimer c correctly points out, 
this fact should be taken into consideration in this type of comparison. 
With another subject, B. F. D., an average of three rest experiments 
with food gave a heat production of 1,244 calories for the 12 hours from 7 a.m. 
to 7 p.m. On one day's work in which he did 419 calories of external muscular 
work, the total heat production from 7 a.m. to 7 p.m. was 3,421 calories; 
thus, the excess due to work was 2,177 calories, corresponding to an efficiency 
of 19.2 per cent. 
A somewhat extensive series of experiments was also carried out with the 
subject A. L. L., an abstract of which is given in table 106. Although the 
base-line for computing the resting metabolism was not so satisfactory as 
could be desired, work experiments were likewise made with two other sub- 
jects, B. F. D. and E. F. S. The results of these experiments are abstracted 
in table 107. 
a Atwater and Benedict, U. S. Dept. Agr., Office Exot. Stas. Bui. No. 136, 1903, p. 190. 
6 Benedict and Carpenter, U. S. Dept. Agr., Office Expt. Stas. Bui. No. 208, 1909. 
c See editor's note to article byTigerstedt in Oppenheimer's Handbuch der Biochemie, Jena, 1908, 4 (2), p. 45. 
