12 METABOLISM DURING WALKING. 



unable to detect any increasing effect of the grade, but the condition 

 of the path had a marked effect in lessening the efficiency. Durig 

 lays considerable emphasis in this report upon the question of the 

 basal value to be used. He questions the correctness of the procedure 

 of deducting a value for a horizontal component based upon results 

 found in horizontal-walking experiments, which necessarily assumes 

 that the expenditure of raising the body at each step in horizontal 

 walking is the same as for grade walking, although he computed the 

 energy cost for grade walking by this method. Undoubtedly, as 

 Durig suggests, the greatest error in all the efforts to study the energy 

 cost per kilogrammeter of grade-lift lies in assessing the value for the 

 horizontal component. 



A comprehensive and thorough study of the energy expenditures of 

 grade walking, per se, was carried out by Brezina and Kolmer 1 in 

 Durig's laboratory with a motor-driven treadmill which could be 

 adjusted to various grades and speeds. In addition to the level 

 walking experiments, experiments were made with the subject walk- 

 ing on grades of 4.7, 10.0 (ca.), 18 (ca.), 27.9, 35 (ca.), 39, and 42 per 

 cent, while the total weights moved, including loads, were 70, 84, 93, 

 104, 114, and 124 kg. The speed of walking varied with the grade 

 and the load, but the range was approximately 18 to 45 meters per 

 minute. Naturally the lowest speeds were used on the higher grades. 

 The method used in determining the basal metabolism was that of 

 Zuntz, but the gas-meter was not carried on the back. The experi- 

 ments were made with Brezina as the subject and in the forenoon, 

 If hours after a breakfast consisting only of a cup of sweetened tea. 

 In the calculation of the results, an average basal metabolism of 1,083 

 gram-calories per minute was deducted, this being derived from earlier 

 experiments with Brezina. For the level walking they found an 

 average value of 0.51 gram-calorie per horizontal kilogrammeter. The 

 maximum amount of work done was at a grade of 27.9 per cent, when 

 a weight of 104.5 kg. was moved at a speed of about 30 meters per 

 minute. This produced 900 kg. m. of work, with an energy output 

 above the basal of 10,000 gram-calories per minute. Brezina and 

 Kolmer found a considerable variation in the respiratory quotients, 

 but on the whole the increases obtained depended upon the amount of 

 work done. In the experiments when the larger amounts of work 

 were performed, the respiratory quotient was found to be as high as 

 0.98 and there were many experiments with a quotient over 0.95. 



The results of Brezina and Kolmer are further discussed by Brezina 

 and Reichel, 2 who consider the data from a mathematical standpoint. 

 These authors had previously shown 3 that the energy factor for the 



1 Brezina and Kolmer, Biochem. Zeitschr., 1914, 65, p. 16. 

 2 Brezina and Reichel, Biochem. Zeitschr., 1914, 65, p. 35. 

 3 Ibid., 63, p. 170. 



