242 METABOLISM DURING WALKING. 



The values for H. R. R. were fairly uniform, averaging 7.5 gram- 

 calories, with a range in work performed of 452 to 717 kg. m. The 

 highest value of 8.0 gram-calories was in the one experiment with a 

 15 per cent grade. T. H. H. also performed his task at an average 

 energy cost of 7.6 gram-calories, although his daily work did not 

 exceed 392 kg. m. as compared with 717 kg. m. for H. R. R. 



W. K. on his first day, with a 3.6 per cent grade, did only 131 kg. m. 

 of work, and his low heat cost for this work of 5.3 gram-calories may be 

 assumed as due largely to the difficulty of measuring the heat differ- 

 ences in these small amounts. His maximum cost was 9.3 gram-calo- 

 ries when 719 kg. m. of work were done and the average value 8.1 

 gram-calories. 



With E. D. B. the range was wider than for any of the five men. His 

 lowest daily cost per kilogrammeter was 4.8 gram-calories, and a closely 

 approximate value was found on several other days. Although these 

 low values are not necessarily for the period of the least amount of 

 work, in all but one case the work performed was below 200 kg. m. and 

 the heat due to the grade work as computed constitutes approximately 

 but one-fourth of the total heat measured. These low values appear 

 both in the early period of grade walking and again on the last day, 

 when a 2.5 per cent grade was walked, with an outlay of 59 kg. m. It 

 seems probable, therefore, that the low increment in the heat-output 

 per kilogrammeter found with A. J. 0., W. K., and E. D. B. is due to 

 the method of apportioning the heat for standing and horizontal 

 walking requirements, rather than to the fact that the values were 

 actually low. The average increment due to grade-lift for E. D. B. was 

 7.0 gram-calories, and for the group of five subjects, 7.2 gram-calories. 

 Omitting A. J. 0. from the average, since he had but one experiment, 

 the average value for the four remaining subjects is 7.6 gram-calories 

 per kilogrammeter of work done. 



In the discussion of the results of the horizontal- walking experiments, 

 it was seen that some evidence of a training effect appeared in the later 

 experiments with E. D. B. (See tables 34 and 43, pp. 141 and 159.) 

 The data obtained in the experiments on grade walking do not offer 

 so great an opportunity for a study of the effect of training upon the 

 oxygen consumption and the heat-production with a definite amount of 

 work as might be expected, owing to the difference in the conditions of 

 the experiments and to the more or less progressive increase in work as 

 the research continued. This increase in work was due to the fact 

 that in the earlier experiments the lower grades were used when the 

 subject was less practiced in walking, and as the series progressed the 

 grades were gradually increased, so that in the later experiments the 

 higher grades were used when the subject may be said to have been 

 trained in walking. Near the close of E. D. B.'s five months of service 

 as a subject, low grades were again used in a few experiments, and 



