172 MUSCULAR WORK 
we have no means of knowing except that the results of the experiments which 
extended over considerable periods of time, with the single exception of the 
experiment of April 16, show that this influence persists for at least 5 or 6 
hours. The results of experiments made in the respiration calorimeter at 
Middletown show that this increased metabolism continues even longer. 
We are distinctly inclined to sustain Jaquet's contention, therefore, that rest- 
ing metabolism experiments should not be undertaken for a considerable 
period of time after the work of ascent has been accomplished. 
While the carbon-dioxide excretion does not show such large increases as 
do the oxygen consumption and the calorie output, nevertheless the effect 
is noticeable, and we are therefore unable to agree with Higley and Bowen ° 
who came to the conclusion that after the cessation of work the output of 
carbon dioxide decreases to the normal amount inside of 2 minutes or less. 
These investigators, by means of an ingenious chemograph, studied the car- 
bon-dioxide excretion during bicycling. Although the experiments were of 
short duration, from the one curve given by the investigators in their report, 
it can be computed that the work was sufficient to produce about 2,500 c.c. 
of carbon dioxide per minute. Of further significance is the fact that the puise- 
rate fell inside of 1 minute after the work stopped and then remained at a 
point approximately 20 per cent above normal. While the apparatus was 
chiefly designed to study the effect of bicycling on the excretion of carbon 
dioxide, it is to be wished that the authors had continued their observations 
for a longer time after the working period ceased. 
The intimate relationship between the pulse-rate and the metabolism 
is strikingly emphasized by the distinct tendency shown for the pulse-rate 
to assume a much higher level after work than before — a level that is roughly 
approximate to the increase in the total metabolism. The respiration-rate, 
on the other hand, does not alter greatly. Since they were reported primarily 
to show the influence of muscular activity on the pulse-rate, the observations 
of Pembrey b are of interest here. One of his subjects before the test had a 
pulse-rate of 70; immediately after running 2 miles, the pulse-rate was found 
to be 164; 10 minutes later, 128; 30 minutes later, 100; and 60 minutes 
later, 82. Another subject had a pulse-rate before running of 66; immediately 
after running the 2 miles, the pulse-rate was 140; after 2 minutes, 120; 
after 33 minutes, 106; after 77 minutes, 84; and 107 minutes afterwards, 74. 
A second test with the same subject showed a pulse-rate before running of 56; 
immediately after the run, 136; 15 minutes afterwards, 104; 45 minutes 
afterwards, 88; and 75 minutes afterwards, 86. In all of these observations, 
it will be seen that the pulse-rate remained at a considerably higher level 
after the exercise than the resting value obtained before the run. 
We believe that our observations give convincing evidence that the in- 
creased pulse-rate noted as an after-effect of muscular work is accompanied 
by a distinctly higher metabolism — a metabolism which thus far has not been 
given due consideration in investigations on the metabolism following mus- 
cular work. 
o Higley and Bowen, Am. Journ. Physiol., 1904, 12, p. 311. 
6 Pembrey, Physiology of muscular work in Further advances in physiology, edited by Leonard Hill, London, 
1909, p. 208. 
