DISCUSSION OF RESULTS. 91 



As we have already seen from the discussion in an earlier section, 1 

 the metabolism in the standing relaxed position after the ingestion of 

 food was considerably greater than that obtained when the subject was 

 without food, this being due to the katabolic stimuli of the foodstuffs. 

 Of most importance, however, is the question whether the increment due 

 to walking is superimposed upon the increased katabolism due to food 

 or whether this increment is lessened by the fact that the body is 

 previously stimulated to a greater katabolic activity. With a view to 

 studying the influence of variations in the intensity of the pre-walking 

 stimulation, certain of the diets were so controlled as to consist in 

 large part of one of the three principal food constituents, i. e., protein, 

 fat, or carbohydrate. With the experimental conditions and the impos- 

 sibility of controlling the subject's diet while he was outside of the 

 laboratory, it was impracticable to make a thorough study of this par- 

 ticular phase of the problem. Our data do not therefore present a 

 conclusive statement as to the influence of the special protein, fat, or 

 carbohydrate diets, but merely contribute to the interesting question 

 as to whether or not the increase in the katabolism following the inges- 

 tion of food persists during increased muscular activity or if there be a 

 summation effect under these conditions. 



Since we have seen not only from the work of previous investigators, 

 but from tables 14 and 15, that there is a marked influence upon the 

 heat per unit of work as the result of an increase in velocity, particu- 

 larly when the velocity is above 95 meters per minute, it seems prefer- 

 able to consider the data presented in table 16 from this point of view. 

 As in the experiments with this subject when no food was taken, here 

 again we find that in the greater number of the experiments the speed 

 varied from 52.7 to 81.1 meters per minute, there being but 7 periods at 

 speeds ranging from 106 to 113.7 meters per minute, and but 4 periods 

 with a speed over 140 meters per minute. 



Considering first the experiments at the lower speed, we find that 

 91 periods are available for study. The average velocity during these 

 periods was 68.2 meters per minute and the heat per unit of work done, 

 i. e., per horizontal kilogrammeter, was 0.486 gram-calorie. It will be 

 seen from the table that the standing basal value for the total heat- 

 output per minute in the experiments with food ranged from 1.24 to 

 1.61 calories per minute, averaging considerably above those obtained 

 when the subject was standing in the post-absorptive condition. On 

 the other hand, since the average value per unit of work done in 57 

 periods without food was 0.493 gram-calorie and the average of 91 

 periods with food was 0.486 gram-calorie, it is clear that the increase 

 over the basal metabolism was the same in both instances; in other 

 words, the increment due to the work of forward progression was 



l See p. 75. 



