96 MUSCULAR WORK 
While such an explanation as the conversion of fat to carbohydrate is 
a possible one, it must not be forgotten that the conditions under which these 
low " after-work " quotients are obtained are far from ideal, as the subject is 
somewhat restless, and his temperature, pulse, and respirations are all above 
normal and rapidly falling, — experimental conditions we believe not suitable 
for obtaining data which are to be compared with the normal. 
Estimates of the Amount of Carbohydrate in the Body. 
This exhaustive study of the respiratory quotient in connection with an 
excessive amount of external muscular work leads to interesting conclusions 
as to the probable amount of carbohydrates stored in the body. The amount 
of glycogen in the different muscles and organs of animals has been frequently 
determined. An attempt has also been made to compute the carbohydrate 
content of the body from the amputated limbs of adults and the bodies of 
infants. From the results of such investigations, it has been commonly 
reported that the body of a human adult contains normally not far from 400 
grams of glycogen, but, as already shown in this report," the relative amount of 
glycogen may vary considerably according to the muscular activity and the 
previous diet — a point also emphasized by Benedict and Higgins. 6 
One of the experiments in this present series of work experiments offers 
evidence which seems to us the best thus far procurable as to the probable 
minimum amount of carbohydrate in the body of an active, well-nourished 
athlete. It should be borne in mind that these were all post-absorptive 
experiments, i. e., at least 12 hours after the last meal, and they deal, there- 
fore, not with the carbohydrates unabsorbed in the intestinal tract but with 
carbohydrates in the body, chiefly glycogen. On March 15, 1912, the pro- 
fessional subject M. A. M. began work at 8 h 30 m a.m. and continued without 
cessation until 12 h 52 m p.m., the severe muscular work corresponding to a 
total calorie output of 9.75 calories per minute. Inasmuch as the work covered 
a period of 262 minutes, or 4 h 22 m , at the rate of 9.75 calories per minute, 
the total energy output during this period was 2,554 calories, or approxi- 
mately 600 calories an hour. During this period of severe work six respira- 
tory quotients were obtained, 0.90, 0.91, 0.89, 0.89, 0.97, and 0.88, the aver- 
age quotient throughout the period being 0.91. 
Magnus-Levy c has computed that with a respiratory quotient of 0.90, 
assuming that 15 per cent of the total energy is derived from katabolized 
protein, 61 per cent would be derived from the combustion of carbohydrates 
and 24 per cent from that of fat. As a matter of fact, in these experiments the 
subject probably derived much less than 15 per cent of the total energy from 
protein, and we could accordingly use Magnus-Levy's figures for a combustion 
consisting wholly of carbohydrates and fat, with a negligible amount of energy 
resulting from protein combustion. In this case Magnus-Levy computes for 
a respiratory quotient of 0.90, that 66 per cent of the energy is derived from 
carbohydrates instead of the 61 per cent mentioned above. Using the lower 
value of 61 per cent, however, we find that of the total energy produced 
during the 262 minutes of work, namely, 2,554 calories, 1,558 calories would 
be ascribable to carbohydrates. Using 4.23 calories as the heat of combustion 
a See pp. 88 and 89. & Benedict and Higgins, Am. Journ. Physiol., 1912, 30, p. 217. 
" Magnus-Levy, in von Noorden's Handbuch der Pathologie des Stoffwechsels, Berlin, 1906, 1, p. 207. 
