METABOLISM WITH GRADE WALKING. 



225 



M. A. M. in both cases represent measurements in only one period of 

 the same length. By comparing these maximum values with the 

 average standing requirements for the two subjects W. K. and E. D. B. 

 (see tables 5 and 6, pp. 44 and 46), we find a percentage increase in the 

 carbon-dioxide elimination and oxygen consumption of 1,057 and 

 818 per cent, respectively, for W. K., and 1,416 and 1,205 per cent, 

 respectively, for E. D. B. 



In figures 16 and 17 the total carbon-dioxide production per minute 

 versus the kilogrammeters of work is plotted for the different grades for 

 four of the subjects. From these curves it may be seen that the car- 

 bon-dioxide production per minute for all of the subjects increased 

 uniformly with the increase in the amount of work performed. With 

 both W. K. and E. D. B. the curves for the various grades show a 

 general parallelism. The significant feature of these curves is, however, 

 their relative position, in that the curve for the higher grade always 



Kg.ms. 200 



400 



600 



800 



1000 



FIG. 16. Total carbon-dioxide production of T. H. H., 

 H. R. R., and W. K., referred to kilogrammeters of 

 work performed in walking on different grades. (Val- 

 ues per minute.) 



lies beneath the curve for the next lower grade. For instance, in the 

 curves for W. K. in figure 16, that for the 25 per cent grade lies below 

 the curve for the 20 per cent grade, the curve for the 20 per cent grade 

 lies below that for the 15 per cent grade, etc. As the work done is the 

 product of the grade, body-weight, and distance walked per minute, 

 and the body- weight may be taken as constant, when the same amount 

 of work is performed with two different grades, this is due to a change 

 in the speed of walking. The relative position of these curves shows, 

 therefore, that while the men were able to accomplish identical amounts 

 of work on the high and low grades by walking more rapidly on the low 



