102 
PHYSIOLOGY: BENEDICT AND SMITH 
THE INFLUENCE OF ATHLETIC TRAINING UPON BASAL 
METABOLISM 
By Francis G. Benedict and H. Monmouth Smith 
NUTRITION LABORATORY. CARNEGIE INSTITUTION OF WASHINGTON AND CHEMICAL 
LABORATORY, SYRACUSE UNIVERSITY 
Presented to the Academy, January 13, ]9I5 
Two fundamental conceptions exist with regard to the heat production 
of the body. One is that the heat production is proportional to the active 
mass of protoplasmic tissue; the other, and more generally accepted view, 
is that the heat production is proportional to the surface area of the body. 
To throw light upon this question we have made an investigation upon 
the metabolism of a number of trained college athletes in whom the 
proportion of active protoplasmic tissue would undoubtedly be greater 
than that in the body of a normal, untrained individual. In consider- 
ing the results of this study, the differences in surface area have been 
eliminated by making the comparisons only between groups of individuals 
with like height and weight. 
Fifteen athletes, varying in weight from 88.5 kg. to 56.3 kg., were 
studied by means of the universal respiration apparatus, the subjects 
being in a condition of complete muscular repose and in the post absorp- 
tive state, i.e., at least 12 hours after the last meal. Only the average 
values of several closely agreeing tests with each subject are used in the 
comparisons. From an extended series of metabolism experiments on 
normal individuals a sufficient number of suitable non-athletes of similar 
height and weight are selected for a series of comparisons which are made 
in ten groups. Of these ten groups the first four are given in the table 
herewith, thus serving to indicate the method of comparison as well as 
the actual values found in the four groups. In the complete comparison 
we found that in the ten groups the heat production per kilogram of body 
weight was greatest with the athletes in all but two groups, and in these 
two there was no difference between the athletes and non-athletes. The 
heat production per kilogram per 24 hours averaged for the athletes 
26.0 calories and for the comparable non-athletes, 24.4 calories. 
Per square meter of body surface the athletes again exceeded the 
metabolism of the non-athletes in all groups with but slight increases 
in 3 groups. The average heat production per square meter per 24 hours 
was 863 calories with the athletes and 807 calories with the non-athletes. 
In general there was a distinct tendency for the athletes to have 
a measurably larger basal resting metabolism (about 7%) than the non- 
