10 METABOLISM DURING WALKING. 



per cent at Capanna Gnifetti; for J. L., 28.4, and 26.0 per cent; and 

 for L. Z., 26.7 and 27.8 per cent, respectively. 



Biirgi, 1 in a study on the effects of training, made ascents of 25 per 

 cent grade at Brienz (734 meters) and the Rothqrn (2,184 meters); 

 also on the Gornergrat, where the grade was 19.3 per cent and the height 

 2,987 meters. The carbon dioxide only was determined in these 

 experiments. 



From Biirgi's results, Durig 2 has computed the energy required per 

 kilogrammeter of grade work, using an assumed respiratory quotient 

 of 0.80, and found it to be 8.6 to 9.8 calories at Brienz, 10.2 to 12.3 

 calories on the Rothorn, and 9.3 calories on the Gornergrat. After 

 training the expenditures were lower. 



Frentzel and Reach, 3 in their study on the source of muscular power 

 reported some experiments in which the subject walked on the tread- 

 mill with a grade of 23 per cent. These experiments, however, were 

 not made with the man in the post-absorptive condition, but after a 

 special diet of carbohydrates, proteins, or fats. From the data for the 

 gaseous exchange the computed efficiencies are 36.4 for F. and 35 per 

 cent for R. 



Zuntz and Schumburg, 4 in their comprehensive study of marching, 

 included a few experiments on grade walking. These, however, were 

 made with a grade of only 6.5 per cent. We have computed an effi- 

 ciency from their data of 31.2 per cent. 



Durig and Zuntz 5 give the energy expended by themselves when 

 walking on the glacier of Monte Rosa as 14.65 and 9.76 calories per 

 kilogrammeter of work. The low efficiencies are obviously attribut- 

 able to the poor footing. 



Durig, 6 in 1906, made some grade studies upon himself 1| to 2 

 hours after a light breakfast, when walking with a load of 18 kg. on 

 the Bilkengrat at grades of 25 to 27 per cent. In all, 33 experiments 

 were reported, showing an efficiency of 25.6 to 29.8 per cent. The 

 average expenditure was 7.9 calories and the average efficiency 29.5 

 per cent. Durig found that the efficiency increased with practice. 

 He also found a greater metabolism in the first periods of the day, 

 indicating need of practice for each day, that the path conditions had 

 little effect, and that the respiratory quotient had a tendency to fall. 



In 1901, Zuntz and his colleagues, A. Loewy, Miiller, and Caspari, 7 

 spent the summer upon Monte Rosa, where elaborate studies were 



'Biirgi, Arch. f. Anat. u. Physiol., Physiol. Abth., 1900, p. 509. 



*Durig, Denkschr. d. math.-natur. Klasse d. kaiserl. Akad. d. Wissensch., 1909, 86, p. 300. 

 Frentzel and Reach, Arch. f. d. ges. Physiol., 1901, 83, p. 477. 

 4 Zuntz and Schumburg, Physiologic des Marsches, Berlin, 1901. 



B Durig and Zuntz, Travaux de 1'annde 1903, Laboratoire scientifique international du Mont 

 Rosa, Turin, 1904, p. 65; also Arch. Anat. u. Physiol., Physiol. Abth., 1904, Suppbd., p. 417. 

 6 Durig, Arch. f. d. ges. Physiol., 1906, 113, p. 213. 

 7 Zuntz, Loewy, Miiller, and Caepari, Hohenklima u. Bergwanderungen, Berlin, 1906. 



