92 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING. 



constant, irrespective of whether the subject was with or without food, 

 this being true for subject II with the rate of speed varying from 52.7 

 to 93.3 meters per minute. 



At moderate speeds above 100, we have seven periods with food in 

 which the velocity varied from 106 to 113.7 meters per minute, the 

 average speed being 1 1 1 .4 meters per minute, and the average output of 

 heat per unit of work done 0.606 gram-calorie. Certain difficulties 

 appear when an attempt is made to compare the results of these 

 periods with food with periods without food. First, the speed per 

 minute without food was 106.3 meters and that with food 111.4 meters, 

 this being a perceptible increase. Second, but few periods are available 

 for comparison either with or without food, there being but 7 for the 

 former and 6 for the latter. If we make such a comparison, however, 

 we find that with food the heat per unit of work is 0.606 gram-calorie, 

 while that without food was only 0.585 gram-calorie. It is probably 

 not possible to attribute this increase in the heat-output per unit of 

 work solely to the increase of 5 per cent in the speed, and we can only 

 state that with speeds averaging 111.4 meters per minute the increase 

 in the heat per horizontal kilogrammeter with food is perceptibly 

 greater than that with food at a speed of 68.2 meters per minute. 



The comparison becomes even more difficult when we consider the 

 experiments with the highest speeds, namely, those of 140 meters per 

 minute and over. Here we have but 4 periods with food, with the 

 speed ranging from 143 to 148.7 meters per minute and an average 

 speed of 146.3 meters per minute. The comparison is still further 

 complicated by the fact that in one of these four periods the subject 

 was running. The average heat-output per unit of work done for the 

 three walking periods was 0.907 gram-calorie and the value found for 

 the one period with the subject running was 0.739 gram-calorie, a 

 value much less than that obtained with the subject walking. 



We may thus say that all of the observations made after the taking 

 of food are completely in accord with those made when no food was 

 taken, i. e., an increase in the energy per unit of work done as the speed 

 increased and a considerably less energy per unit of work done when 

 the subject was running as compared with that when he was walking. 

 An analysis of the processes of running and walking and the character 

 of the steps is necessary to interpret these differences intelligently. 1 



Electrocardiograms of the pulse-rate were obtained in a few of the 

 experiments following the ingestion of food, namely, those of April 4, 

 6, and 7. 2 These records show the same discrepancy between the pulse- 

 rate and the metabolism as was found in the experiments without food. 3 



'See p. 98. 2 See table 4, pp. 54 and 55. 3 See p. 85. 



