250 



METABOLISM DURING WALKING. 



naturally results in an increased amount of work. To compare more 

 directly the effect on the efficiency of the work performed, the average 

 efficiency for both W. K. and E. D. B. with increasing amounts of 

 work is given in table 69. These average values are a composite for 

 different grades and speeds and show in each case that, as the work 

 increases, the efficiency diminishes. 



TABLE 69. Relation between efficiency in grade-lift and amount of work 

 performed in grade walking by W. K. and E. D. B. 



When the periods for each day are compared, we find that the effi- 

 ciency tends to fall as the forenoon progressed, this drop being apparent 

 for all subjects, grades, and speeds. It is believed that this is due to 

 fatigue, for though the subject may not be conscious of it for some hours, 

 the onset of fatigue must be early in the performance of work. It must 

 be admitted, however, that no connection appears between the amount 

 of the decrease hi efficiency and the amount of work done. Thus, 

 with E. D. B. in the two periods on February 22, when he did over 

 1,500 kg. m. of work, there was a decrease in the second period of but 

 0.5 per cent, while on several days when he performed less than one- 

 third this amount of work the efficiency fell during the forenoon 

 1 to 2 per cent. It is perfectly possible that the subject's physical 

 condition played a part here which obscures the comparison. 



The average efficiencies of these five subjects as given in table 70 is 

 33.4 per cent; if we exclude A. J. O., with whom there was but one 

 experiment with a low grade, we find the average to be 31.3 per cent. 

 The lowest average efficiency was with W. K. at 29.4 per cent, and the 

 highest with E. D. B. at 33.7 per cent. The results for H. R. R. are, 

 we confess, surprising. From our observation, which was influenced, 

 no doubt, by the fact that this subject practically collapsed after the 

 sixth period on May 1, while performing but 550 kg. m. of work, we 

 expected much lower efficiencies from him than from the others, and 

 yet his average value of 31.1 per cent is in accord with that of T. H. H. 

 and of W. K. It should also be mentioned that in the last period of 

 May 1, just before he succumbed, the efficiency for H. R. R. was not 

 different from that in the three preceding periods. The efficiencies of 



