146 MUSCULAR WORK 
A further complication lies in the fact that in the experiments particu- 
larly planned for comparison purposes, a different amount of work was per- 
formed in one set than in the other; since this would materially affect the 
efficiency, it has been taken into consideration in making up the table. 
Three groups of experiments, each containing three individual experiments, 
have been selected for comparison in which the heat equivalent of the external 
muscular work was not far from 2 calories per minute. Six of these days were 
with a carbohydrate-rich diet and three with a carbohydrate-poor diet. 
In three other experiments, namely, those of January 17, 18, and 19, 
the diet was carbohydrate-poor and the heat equivalent of the muscular 
work averaged only about 1.57 calories. Inasmuch as no experiments with a 
carbohydrate-rich diet were made with a comparable amount of work, the 
three experiments of January 8, 9, and 15 were selected for comparison. 
In these experiments, the heat equivalent of the muscular work was approxi- 
mately 1.57 calories; the preceding diet was, however, unrestricted, but as 
the average respiratory quotients were respectively 0.88, 0.88, and 0.90 
when the subject was lying upon a couch before work, it can be assumed that 
they are fairly indicative of a rich glycogen supply and hence suitable to be 
compared with the experiments of January 17, 18, and 19, in which the 
respiratory quotients of 0.77, 0.77, and 0.77, respectively, indicated a rela- 
tively low glycogen storage. 
The six experiments with a carbohydrate-rich diet in which the heat 
equivalent of muscular work was about 2 calories per minute gave an average 
output per calorie of external work per minute of 5.37 calories. On the three 
days with a carbohydrate-poor diet with which they are compared when es- 
sentially the same amount of work was performed, the average output per 
calorie of external muscular work per minute was 5.31 calories. On the days 
when less work per minute was performed, we have for the experiments with 
a diet presumably rich in carbohydrates an average of 6.66 calories per 
calorie of external muscular work per minute, while on the three days with a 
carbohydrate-poor diet, there were 6.68 calories per calorie of external mus- 
cular work per minute. It is thus seen that both the sets of experiments 
compared show approximately the same efficiency irrespective of the diet. 
Making all allowance for the inadequate control of the diet, the evidence 
obtained from these experiments is strongly at variance with the conception 
that with a fat diet there will be an increase of 30 per cent in the energy out- 
put per calorie of external muscular work over that with a carbohydrate-rich 
diet. While it must be borne in mind that the carbohydrate-poor diet was 
not a carbohydrate-free diet, yet the fact that the experiments with the diet 
poor in carbohydrates showed not the slightest indication of an increase in 
the energy output per unit of work is strongly suggestive of the absence of 
the transformation during work of fat to glycogen with a consequent libera- 
tion of unavailable heat. 
