96 ENERGY TRANSFORMATIONS DURING HORIZONTAL WALKING. 



which it was demonstrated that this subject had ridden the equivalent of 

 100 miles over average roads on an empty stomach; but in this research 

 it was impracticable to carry out prolonged endurance tests at high 

 rates of speed. Indeed, at the highest speed, i. e., 140 kilometers per 

 minute, it is very certain that the subject would have run instead of 

 walked, as distances as great as 20 or more kilometers are rarely covered 

 rapidly by walking, but usually by running. On the other hand, a 

 speed of 80 meters per minute represents an average rapidity of motion 

 when long-distance walking is to be done and hence the values obtained 

 at this speed have a much greater practical use than would values 

 secured with the subject walking at a higher speed. 



COMPARISON OF THE HEAT-OUTPUT PER UNIT OF WORK DURING RUNNING 

 WITH THAT OBTAINED DURING WALKING. 



The striking difference between the heat per unit of work observed 

 when the subject was running and that obtained when he was walking 

 has already been noted in table 15 (see p. 87), the figures showing that 

 considerably less energy per unit of work was required for moving the 

 body forward in running than in walking under the experimental 

 conditions. The values obtained when the subject was moving 

 forward at the rate of approximately 144 meters per minute give the 

 only data for a direct comparison, no running experiments being made 

 at the lower rates of walking. At this speed, the value computed for 

 walking (using the standing basal value) is 0.932 gram-calorie and for 

 running 0.806 gram-calorie. That these are not accidental figures 

 is shown by the fact that the first value is the average of 7 reasonably 

 agreeing periods and the second value is the average of 15 well agreeing 

 periods; in other words, we deal here with a positive difference of 

 approximately 15 per cent. It thus becomes important to analyze, 

 if possible, the mechanical movements incidental to walking, and par- 

 ticularly rapid walking, to find the reason for this discrepancy. 



Traveling at the speed of 144 meters per minute, the ordinary 

 individual without load generally runs rather than walks. On the 

 other hand, in transporting heavy material as, for example, military 

 accouterments and trappings, running would be wholly impracticable 

 and walking must be resorted to. It has been noted, especially in 

 observations of professional walkers, that in rapid walking there is 

 commonly very great extraneous arm movement, the arms being 

 violently swung back and forth with each step. In the belief that this 

 unusual extraneous muscular movement results in a large energy 

 transformation which does not directly contribute to the forward pro- 

 gression, the study previously referred to was made in which the energy 

 requirement of subject II was observed while he stood and swung his 

 arms violently as in rapid walking. These values have already been 

 discussed in connection with the standing resting values, 1 when it was 



'See table 10 and p. 71. 



