PHYSIOLOGICAL EFFECTS 
155 
pared with an initial value before work of 64 per minute. With this intensity 
of work, therefore, which was nearly 50 per cent greater per minute than that 
in the experiments shown in fig. 6, there was an average rise in the pulse-rate 
from 64 to 160 or approximately 35 beats per minute higher than when the 
muscular work was 1.05 calories per minute. 
The curves for the pulse-rate in 5 experiments in which the external 
muscular work was 2.0 calories per minute are given in fig. 8. These values 
show an average pulse-rate before work of about 60 per minute with an almost 
immediate rise inside of 15 or 20 minutes to a level of approximately 163, 
180 
170 
160 
150 
140 
130 
120 
U0 
100 
90 
80 
70 
60 
50 
10 20 30 4© 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 
Fig. 8. — Curves showing the pulse-rate when the external muscular work was equivalent 
to 2.0 calories per minute. 
which continued throughout the work. After work the pulse-rate fell rapidly 
but became constant at a distinctly higher level than that before the work 
began. The average maximum rate, i. e., 163 per minute, is but a little 
higher than that with 1.5 calories of work. 
The average values for the pulse-rate in two experiments in which the 
external muscular work was 2.25 calories per minute are plotted in fig. 9. 
The initial pulse-rate before work averaged as usual about 63, rising rapidly 
at the beginning of work, and seeking a level not far from 166, or essentially 
that with the work at 2 calories per minute. After the work ceased, there was 
again a rapid fall with a striking tendency for the pulse to remain above the 
initial level. In view of the single high observation of 180 per minute, it is 
to be regretted that more observations could not have been obtained during 
this severe muscular work. 
As has already been pointed out, some method other than the radial 
pulse or the stethoscope must be used during muscular work in order to obtain 
satisfactory records of the pulse-rate, but these two methods were the only 
ones available at the time, since we did not wish to hamper the subject 
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