176 MUSCULAR WORK 
(1) For light work before severe work, M + U -f Si; and (2) for light 
work following severe work, M + U + aS 2 , in which M equals maintenance 
metabolism, U the metabolism for the unnecessary work due to the extran- 
eous activity, Si the stimulated metabolism before severe work, and S 2 
the stimulated metabolism following severe work. To these two base-lines 
is added the metabolism, W, directly involved in the production of external 
effective work, E, assuming that the value of W is the same in both cases. 
The total energy output, C, is constant in both periods. 
Under these conditions we have: 
C = M + U + GSi + W) = M + U + (St + W) 
M and U are assumed equal in both cases, so that: 
Since Si and S 2 are not equal, it follows that W has a value changing with the 
conditions. Let Wi represent the value before the severe work-period and 
W 2 the value after the severe work, then: 
W 2 <Wi 
and as the effective muscular work remains the same in both periods, 
w*w* 
This observation has its greatest value as a suggestion for further re- 
search. Our data at present permit of no mathematical estimates of the 
values of $i, $ 2 , Wi$ or ^2 but it is not beyond the bounds of reasonable 
speculation to believe that some accurate index of these values may later be 
found. It is evident from our experiments that the principles underlying 
the determination both of the external muscular work and the total work are 
sound. That being the case, an extension of this form of experimenting can 
but lead to fundamental information regarding the physiology of muscular 
work." 
<* As this book goes to press, our attention has been called to the experiments of Boussaguet (Recherches ex- 
penmentales sur les conditions physiologiques du travail des mineurs, Paris, 1912), who used a bicycle 
fitted with a Prony brake. Although numerous measurements of the gaseous exchange are presented in 
a table, there is no discussion of the character or extent of the katabolism nor is the mechanical effici- 
ency computed. 
0, 
