160 
MUSCULAR WORK 
temperature by this method is not entirely practicable. On the other hand 
it did not seem wise to endanger the success of the research by attempting 
to overcome the idiosyncrasy of this individual subject in order to obtain 
observations which were at that time distinctly of secondary importance. 
THE MAXIMUM WORKING CAPACITY OF MAN. 
It is a well known fact that men are capable of intense muscular exertion 
for short periods, and that the intensity of the work is in general inversely 
proportional to the length of time through which it must be carried out. 
On this principle is based all the systems of training for short distances or 
long distances in running races. The results of our experiments throw an 
interesting light upon the possible maximum working capacity of man in 
periods ranging from one to four hours, and hence they are worthy of 
consideration from this point of view. 
In discussing the maximum working capacity of man, R. C. Carpenter ° 
has tabulated the results of several computations regarding the average energy 
equivalent of the work of a man. Of these, the first four are particularly 
interesting in this connection since they give the energy equivalent of bicycle 
riding over periods of 10, 15, and 96 seconds, and 1 hour, respectively. These 
have been recomputed on the basis of calories per minute, and are given in 
table 132. 
Table 132. — Energy equivalent of the work done on bicycle riding 
as reported by R. C. Carpenter. 1 
Time. 
Effective 
muscular 
work per 
minute. 
10 seconds 
cals. 
6.15 
2.94 
2.83 
1.94 
1 Recomputed by us from values given in foot pounds, 3,088 foot pounds being equal to 1 calorie. 
In the data presented by Carpenter, we find that the professional sub- 
ject C. W. M. in a 6-day bicycle race rode an average of 20.77 hours per day 
for 5 days, and accomplished, according to Carpenter's computations, 3,366 
calories of external muscular work per day. This corresponds to 2.70 calories 
per minute, a value considerably better than that given in table 132 for 1 hour. 
It should be borne in mind that this value, as well as the values in table 132, 
are derived from computations of the effective muscular work performed, 
no direct measurements being possible. Our professional subject M. A. M., 
who had personally participated in 6-day races, agreed fully with the subject 
N. B., previously studied, 6 that the resistance of the ergometer, which cor- 
responded to an external effective work of approximately 1.6 calories per 
minute, represented quite closely that incidental to the air and track resistance 
in a 6-day bicycle race. From our experience in this research, therefore, 
we have every reason to believe that the values given by R. C. Carpenter are 
very much too high, the error being due to the inadequate data for computing 
the amount of work done by the bicyclist. Making certain reservations, 
a Atwater, Sherman, and Carpenter, U. S. Dept. Agr., Office Exp. Stas. Bui. 98,"1901, p. 67. 
b Benedict and Carpenter, U. S. Dept. Agr., Office Exp. Stas. Bui. 208, 1909. 
