156 
MUSCULAR WORK 
with a chest pneumograph and a string galvanometer was not then at our 
disposal. It is evident, however, that there is here an interesting field for 
study in the relation between the pulse-rate and the intensity of muscular 
work. 
One of the points clearly brought out in this study of the effect of mus- 
cular work on the pulse-rate is the distinct tendency for the pulse to settle 
190 
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170 
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150 
140 
130 
120 
110 
100 
90 
80 
70 
60 
50 
10 20 30 40 50 60 70. 80 90 100 110 120 130 140 150 160 170 
Fig. 9. — Curves showing the pulse-rate when the external muscular work was equivalent 
to 2.25 calories per minute. 
to a much higher level than prior to work. In connection with fig. 8, it should 
be noted that the pulse-rate continued on a level higher than the initial values 
so long as the observations were made, a record of 76 being obtained 361 
minutes after the beginning of the work. Following one of the experiments 
shown on fig. 9, the high pulse-rate of 70 or over continued up to the 400th 
minute when the observations were discontinued. This is in complete corre- 
lation with the higher metabolism found under these conditions which is 
discussed elsewhere in this report." Our results are strikingly at variance 
with the observations of Cook and Pembrey, 6 who maintain that with well- 
trained persons the pulse-rate after a strenuous run rapidly returned not only 
to the earlier level but actually fell below. Only with poorly trained individ- 
uals did the pulse remain high after exercise. Our subject M. A. M. was 
admirably trained and usually very fit, as the amounts of work done without 
food amply testify. Inasmuch as in our experiments the pulse-rate showed 
an even greater tendency towards this persistency in maintaining a higher 
level after work than did the metabolism, a series of experiments definitely 
planned to study this interesting point should be made; in this research, 
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a See p. 163. 
b Cook and Pembrey, Journ. Physiol., 1912, 45, Proceedings, p. 1. 
