174 MUSCULAR WORK 
continued working but with a very much less load, the oxygen consumption 
would be considerably larger than when the light work preceded the severe 
work. The results given in table 137 do not, however, show this to be the 
case. With K. H. A. on March 7, when the light work followed severe work, 
the average oxygen consumption was 1,076 c.c. per minute with a rate of 
79 revolutions per minute. On April 3, when the same amount of work 
was being performed prior to the severe muscular work, the average value 
shows a slightly less oxygen consumption of 1,057 c.c, a difference that 
must be considered within normal limits. A more satisfactory comparison, 
since the data were obtained on the same day, can be made of the results 
secured in two experiments with the subject M. A. M., in which records 
were obtained before and after the very severe work period. On February 
28, although the rate of revolution was approximately the same before and 
after the severe work, the oxygen consumption was a little less, if anything, 
in the after-period which may have been caused by the slightly lower rate 
of revolution. On March 4, the oxygen consumption was slightly greater 
after the severe work-period, the average before work being 1,105 c.c. and 
after work 1,173 c.c. The remaining comparisons can only be made with 
the values obtained on different days. 
From the data given in this table, therefore, it will be seen that, contrary 
to expectation, the average oxygen consumption after the severe work is 
approximately the same as during the initial period of light work. In making 
this comparison no account is taken of the change in the character of the 
katabolism due to the lowering of the carbohydrate content of the body dur- 
ing the severe work, although, strictly speaking, this should be done, since 
the calorific equivalent of oxygen would be somewhat lower in the period after 
severe work. Obviously making such allowance the calorie output would be, 
on the average, slightly less in the periods following severe work. 
It has been clearly demonstrated in previous comparisons of data that 
the metabolism is stimulated by severe muscular work, but the exact nature 
of this stimulus is at present unknown. That the effect of such stimulus 
persists even when light work follows the severe work is not an unreasonable 
supposition. 
If we assume that there is a definite intensity of metabolism incidental 
to the "warming up," or adjustment of the body to a metabolism sufficient 
to make possible the work required, it will follow that as effective muscular 
work is performed, there must be superimposed upon the resting metabolism 
in addition to that required for effective work this stimulated metabolism, I 
which may be designated as S. After the work has ceased, the stimulated 
metabolism, S, persists for a certain period but continually decreases in in- J 
tensity, becoming zero only after several hours. Following work, then, we 
have the resting metabolism with a continually decreasing stimulated me- | 
tabolism, S, superimposed upon it. 
During work there is still another factor to be considered, i. e., the 
metabolism incidental to the extraneous and unnecessary motions which 
accompany riding, so that when work is performed we have the main- 
tenance metabolism, plus the metabolism necessary for the extraneous ac- 
tivity, plus S, plus the metabolism especially involved in the production 
of effective work. 
/I 
