EXPERIMENTS WITH HORIZONTAL WALKING. 



149 



figures are the average of two days in April, while the averages for the 

 two succeeding groups (40 to 45 meters per minute and 45 to 50 meters 

 per minute) were from experiments made in November and December. 

 The lapse of time between these groups is too great, therefore, to per- 

 mit a statement that the cost increases as the speed falls below a cer- 

 tain comfortable rate of walking. 



The effect of speed upon the energy cost per horizontal kilogram- 

 meter can best be shown for E. D. B. by a consideration of the data 

 for March and April, in which there is a wider range of speed and the 

 influence of training is largely eliminated. These results are given in 

 table 39, from which it is evident that for moderate speeds ranging 

 from 55 to 77 meters per minute, the cost per horizontal kilogrammeter 

 shows no tendency to change, but for speeds of 91 meters per minute 

 the cost increased nearly 20 per cent. The latter speed was a forced 

 one and required considerable exertion on the part of E. D. B. to 

 maintain it. This increase in the energy cost is in full agreement with 

 what Durig has claimed, namely, that the cost per horizontal kilo- 

 grammeter is practically constant for speeds below 80 to 85 meters per 

 minute, above which speed there is a break in the curve and the energy- 

 output increases at a faster ratio. 



TABLE 39. Energy cost per horizontal kilogrammeter with E. D. B. of walking 

 on a level at different speeds in March and April 1916. (Values per minute.) 



In considering the extremely slow speed of 37 meters per minute, it is 

 seen that on the two days of which 0.499 is the average the heat- 

 output was 0.475 and 0.522 gram-calorie per horizontal kilogrammeter, 

 respectively. These values are, unfortunately, not in close agreement. 

 The high value of 0.522 gram-calorie for April 4 might be taken as sup- 

 porting the statement of Frentzel and Reach, 1 that for slow restrained 

 speeds there is an increase in the heat cost per horizontal kilogram- 

 meter. This claim of Frentzel and Reach has been questioned by 

 Durig, 2 who believes that there is not sufficient evidence in Frentzel 

 and Reach's figures to support their statement. The value of 0.475 

 gram-calorie for April 3 lies close to the values found for all the other 



'Frentzel and Reach, Archiv f. d. ges. Physiol., 1901, 83, p. 494. 



2 Durig, Denkschrift. d. math.-natur. Klasse d. kaiserl. Akad. d. Wissensch., 1909, 86, p. 271. 



