14 METABOLISM DURING WALKING. 



even when but one man is used for a subject, may properly be employed 

 for extensive generalizations, until deviations with other subjects are 

 proved. While, therefore, we are in full accord with the criticisms 

 of Cathcart, Lothian, and Greenwood, previously referred to, we still 

 are disposed to consider a series of experiments, such as those made 

 with Brezina, of most fundamental importance in the progress of our 

 knowledge of the physiology of walking. Indeed, in our experiments 

 the importance of contributing further observations on a number of 

 individuals has played a not unimportant role in planning the research. 



Although Amar 1 reported a number of experiments in which the 

 subject was engaged in horizontal walking, we have found in his studies 

 but two with grade walking. These were made with one subject 

 walking on an 8 per cent grade and again on a 13 per cent grade, 

 with and without a superimposed load of 7.3 kg. The experiments 

 are but briefly reported and the data do not lend themselves to an 

 extensive computation of the efficiency. 



In 1912, Douglas, Haldane, Henderson, and Schneider, 2 in an 

 expedition to Pike's Peak, made an extensive series of horizontal- 

 walking experiments which included two grade-walking observations, 

 in which the gradient was 1 in 4, and the speed from 2 to 2.25 miles 

 per hour. The special conditions of altitude, diet, and terrain make the 

 results difficult of comparison with others. 



Waller 3 has made some estimates of the mechanical efficiency shown 

 by men in ascending a staircase while breathing into a Douglas bag. 

 The total volume of air exhaled and the carbon dioxide produced were 

 determined in these experiments. By assuming a respiratory quotient 

 of 0.85, Waller computed the energy expended during the work and 

 believes that 5 per cent was the range of error by this method. He 

 reports data for 12 subjects varying in age from 18.5 to 63 years and 

 in weight from 54.5 to 98 kg., who made the ascent of a 20-meter stair- 

 case at an average efficiency of 33 per cent. 



Waller and de Decker 4 report an average mechanical efficiency of 

 32 per cent for T. R. P. in five ascents of the staircase. Later, in a 

 comparison of bicycle with staircase ergometry, 5 17 experiments with 

 A. D. W. showed efficiencies varying from 24.8 to 41.6 per cent for 

 the staircase work. A complete report of this work of Waller has not 

 yet appeared, but the results thus far published indicate very wide 

 variations. 



Magne 6 has recently made a study of the changes in the energy 



'Amar, Le moteur humain, Paris, 1914, p. 507. 



2 DouKlas, Haldane, Henderson, and Schneider, Phil. Trans. Roy. Soc. London, 1913, ser. B, 

 203, p. 185. 



3 Wallor, Journ. Physiol., Proc. Physiol. Soc., 1919, 52, p. Ixxii. 



4 WaIler and de Decker, Journ. Physiol., Proc. Physiol. Soc., 1919, 53, p. xxx. 



6 Ibid., p. xliv. 



'Magne, Journ. de physiol. et de path, gen., 1920, 18, p. 1154. 



