PHYSIOLOGICAL EFFECTS 175 
From the several methods of computing the efficiency, it appeared that 
in the experiments with a load of 0.5, 0.95, and 1.5 amperes, varying amounts 
of extraneous muscular activity were present. Observations of the tension on 
the sprocket-chain and the general impressions of the subject led us to believe 
that with a load of 0.5 ampere, this extraneous activity played a large role, 
the maximum amount being obtained with this amperage. This was further 
emphasized by the results obtained in computing the efficiency. Since 
observations showed that with a load of 0.95 and 1.5 amperes, there seemed 
to be a definite series of muscular movements for external work, we can assume, 
for purposes of comparison, that the extraneous unnecessary work disappears 
when these amperages are used. Under these circumstances, therefore, with 
moderately severe or severe work, the total metabolism is made up of main- 
tenance metabolism, plus S, plus the metabolism which is involved in pro- 
ducing effective work. 
In order to throw light upon the constancy of the metabolism for effective 
work, it thus becomes necessary to find whether or not the value S is a con- 
stant. Since the values for the gross efficiencies obtained with a load of 0.5 
ampere were essentially constant, we may assume that the total metabolism 
was likewise fairly constant. It has also been demonstrated that the resting 
metabolism remained approximately constant and from an inspection and 
careful consideration of the experimental technique, we can infer that the 
metabolism required for the extraneous work also remained constant. Appar- 
ently, therefore, the value S was constant in the experiments in which a load 
of 0.5 ampere was used. The same may be said of any series of experiments 
with constant load. 
An examination of table 136, however, shows that in general the after- 
effects of work are greater when the rest-period follows severe work, than 
when it follows moderately severe work, i. e., the after-effects of work during 
which the subject consumed about 1,300 c.c. of oxygen per minute were con- 
siderably less than when the rest-period followed work of such an intensity 
as to require from 2,000 to 3,000 c.c. of oxygen per minute. If, therefore, 
the after-effects of work are due to the general stimulus to the higher metab- 
olism required for the work, it is clear that we must infer that this stimulus 
is in a sense proportional to the intensity of the work, so that the value S 
would not be constant under all conditions of load. 
Having disproved the constancy of S under varying load conditions, we 
then have the rather remarkable fact that the total metabolism in fight work 
experiments was approximately constant both before and after severe work. 
Since the basal maintenance metabolism and the metabolism required for 
the extraneous activity were constant in both cases, and the stimulated metab- 
olism, S, required for severe work persists after the severe work ceases, it is 
obvious that in the light work following severe work, the value S must be 
greater than in the initial light work-periods. As the effective work remains 
the same, it follows that the metabolism involved in the production of effec- 
tive work must be smaller, i. e., a larger proportion of the metabolism used 
directly for effective muscular work is converted into external muscular 
work. 
We thus have different base-lines for the work preceding and following 
severe work, which may be represented by the following formulas: 
