150 METABOLISM DURING WALKING. 



days for speeds up to 78 meters per minute, with the exception of that 

 of April 10, while the value of 0.522 gram-calorie on April 4 finds no 

 support in the data for E. D. B. outside of the early experiments of 

 October and that of January 31, when he resumed walking after an 

 interval of three weeks. (See p. 141.) It seems probable that the 

 value of 0.475 gram-calorie represents more nearly the true condition 

 than does the value 0.522 gram-calorie, in which case it would appear 

 to be in agreement with Durig's statement that there is no increase in 

 the energy cost per horizontal kilogrammeter for slow walking. Ob- 

 viously a study of the energy demands for extremely slow walking, 

 i. e., sauntering, would be of considerable physiological interest. 



Our results do not include those for the highest speeds of walking, 

 as during severe grade walking slow speeds must necessarily be em- 

 ployed. In any consideration of the literature on horizontal walking 

 special attention should certainly be given to the series of experiments 

 of Liljestrand and Stenstrom, 1 in which the Douglas bag was used. 

 With both subjects, N. S. and G. L., the energy (expressed as oxygen 

 consumption) per horizontal kilogrammeter shows an astonishingly 

 uniform agreement with all of the best earlier work. Since in some 

 instances, at least, the actual duration of these experiments was but 

 42 seconds, this speaks for ndt only the great applicability of the 

 Douglas-bag method, but likewise for the extraordinary technical skill 

 of the Swedish investigators. This series of experiments fully sub- 

 stantiates Douglas's conclusions as to the applicability of his bag 

 method to studies of the metabolism during exercise. 



EXPERIMENTS WITH SUBJECT "MARKING TIME." 



For comparison with the energy requirements of horizontal walking, 

 it seemed of interest to secure a few measurements when the subject 

 simply "marked time," as representing a degree of activity interme- 

 diate between standing and walking. Data were therefore obtained 

 with W. K. which are given in table 40. In marking time, the subject 

 kept his legs nearly straight, flexing them as little as possible at the 

 knees. He swung the leg mostly from the hip, thus lifting the body 

 the minimum amount, and although there was some lifting of the 

 limbs, it was not like the regulation marking time of the army. This 

 movement was made at an average rate of 101 so-called " steps" per 

 minute. Under these conditions the average metabolism per minute 

 of W. K. was: carbon dioxide, 414 c. c. ; oxygen, 500 c. c. ; heat, 2.42 cals. 



By consulting table 35, page 144, it is seen that these values cor- 

 respond very nearly to his requirement for horizontal walking at a 

 speed of 55 to 60 meters per minute, with steps taken at the rate of 

 106.6 per minute, the heat-output differing only about 3 per cent. 

 It would seem that the energy necessary for horizontal walking is almost 



'Liljestrand and Stenatrom, Skand. Archiv f. Physiol., 1920, 39, pp. 178 and 179. 



