DISCUSSION OF RESULTS. 85 



In two of the walking experiments without food, those of April 6 

 and 7, we were able to obtain electrocardiograms of the pulse of this 

 sub j ect and the results are recorded in table 4 (pp. 54 and 55) . In previous 

 researches a striking uniformity has been found in the changes of the 

 metabolism and the pulse-rate, amounting at times to a distinct 

 percentage relationship between them. Such a uniformity was noted 

 by Benedict and Cathcart in their study of a bicycle rider when the 

 metabolism and pulse-rate during riding were compared with the 

 values obtained in the lying or sitting position. In this research, on 

 the contrary, the pulse-rate in the experiments of April 6 and 7 showed 

 a distinct lowering when the subject changed from the standing posi- 

 tion to walking, particularly in the experiment on April 7, notwith- 

 standing the fact that the total metabolism during walking increased 

 from 100 to 200 per cent above the basal metabolism of standing. 

 This lowering of the pulse-rate was so positive that it is difficult to 

 believe that any error was made in the measurements. Furthermore, 

 in the fourth period of the experiment on April 7, we find that the pulse- 

 rate with the subject standing after walking increased materially over 

 that during walking. The evidence thus implies that when standing 

 still upon the treadmill, this subject had a much higher pulse-rate than 

 when he was walking at a slow speed. These records are entirely 

 contrary to our previous experience but the lowered pulse-rate during 

 walking has been confirmed by Professor H. Monmouth Smith, of the 

 Laboratory staff, in similar experiments with three other subjects, thus 

 establishing the fact. Further experimenting is now in progress and 

 the results will be incorporated in a subsequent report. 



INFLUENCE OF VELOCITY. 



On all days subsequent to May 4, with the single exception of May 

 13, the speed of walking exceeded 100 meters per minute. At this 

 higher speed there was a distinctly higher energy requirement per 

 horizontal kilogrammeter. Thus, we have six periods when the rate 

 of walking was from 102 to 114.5 meters per minute and averaged 106.3 

 meters per minute. At this speed the average heat-output per hori- 

 zontal kilogrammeter was 0.585 gram-calorie, a material increase over 

 0.493 gram-calorie, the average heat-output for the lower speed. A 

 further grouping of the experiments is permissible when the speed 

 ranged from 139.6 to 148.7 meters per minute, as with this higher 

 speed a considerable increase is shown in the heat requirement per unit 

 of work. Some of the experiments in this group show that when the 

 subject ran instead of walked, the heat-output per horizontal kilo- 

 grammeter was lowered, although the rate of progression was prac- 

 tically the same; accordingly we may not advantageously draw average 

 values. In the two walking experiments on May 6 and 10 the speed 

 averaged 143.7 meters per minute and the heat per horizontal kilo- 

 grammeter 0.929 gram-calorie. In the first period of the experiment 



