252 



METABOLISM DURING WALKING. 



computation employed. It may be said that these net efficiencies are, 

 as a rule, lower than for walking and are nearer 27 to 28 per cent than 

 they are to 33 per cent. The first studies made with the bicycle 

 ergometer were carried out by At water and Benedict 1 and showed net 

 efficiencies of 19.6 per cent as an average of 14 experiments. Later 

 experiments reported by Benedict and Carpenter 2 showed efficiencies 

 of 20 to 23 per cent, and other experiments by Benedict and Cathcart 3 

 with a professional bicyclist, M. A. M., gave efficiencies approaching 

 33 per cent. 



TABLE 71. Efficiency of men in treadmill walking with different grades, as 

 summarized by Durig. 1 (Values per minute.) 



1 Durig, Denkschr. d. math.-natur. Klasse d. kaiserl. Akad. d. Wissensch., 1909, 86, p. 299. 

 2 Ibid., p. 341. An apparent typographical error in the average for the heat-output per kilo- 

 grammeter of grade-lift for 21.6 per cent grade has been corrected here. 



It may be stated, therefore, that the human machine can accomplish 

 various forms of muscular work at a net efficiency greater than 25 per 

 cent, and that grade walking is the most efficient of the various forms 

 of exercise thus far studied, the efficiency for this probably being 33 or 

 more per cent. 



J Atwater and Benedict, U. S. Dept. Agr.. Office Exp. Sta. Bull. No. 136, 1903, p. 190. 

 'Benedict and Carpenter, U. S. Dept. Agr., Office Exp. Sta. Bull. 208, 1909. 

 'Benedict and Cathcart, Carnegie Inst. Wash. Pub. No. 187, 1913, p. 121. 



