METABOLISM WITH GRADE WALKING. 



231 



65 meters per minute (about 2.5 miles an hour). It may also be seen 

 that the respiratory quotient tended to increase as the grade and speed 

 increased. This is more apparent in figure 20, in which the respiratory 

 quotients for W. K. and E. D. B. given in table 56 have been plotted 

 for experiments with varying degrees of work. In this chart the 

 majority of the respiratory quotients up to approximately 600 kg. m. 

 of work fall within the limits of 0.80 to 0.87, i. e., the normal post- 

 absorptive respiratory quotients, and for 700 to 1,000 kg. m. of work, 

 almost half of the respiratory quotients are 0.90 or above, while 

 none are below 0.85. For more than 1,100 kg. m. the respiratory 

 quotients are grouped around 0.93 and none are below 0.90, while 

 the two determinations with work greater than 1,300 kg. m. give respi- 

 ratory quotients of 0.97. Figure 20 gives clear indication that for 

 such short periods as these, 600 kg. m. or less of work per minute do not 

 tend to alter the character of the respiratory quotient, but with moder- 

 ately heavy to heavy work, involving over 600 kg. m. per minute, the 

 body alters its metabolism by a tendency to a selective consumption of 

 its carbohydrate reserve. 



TABLE 60. Comparison of respiratory quotients of E. D. B. during grade walking for the 

 days of the week November 1 to December 11, 1915. (Subject in post-absorptive condition.) 



thanksgiving Day. 



2 Rock candy in supper preceding day. 



3 Molasses candy in supper preceding day. 

 4 Candy and nuts in supper preceding day. 



Zuntz and Schumburg 1 and Durig 2 have stated that work pro- 

 longed over a series of days tends to reduce the carbohydrate store in 

 the body with a simultaneous lowering of the respiratory quotient and 

 that a rest of one day in three is desirable in order to maintain a normal 

 quotient. Contrary to the results of these authors, an inspection of 

 the respiratory quotients for W. K. shows no evidence of a tendency for 

 the quotient to decrease on successive days of walking with a subse- 

 quent increase on the omission of an experimental day. With E. D. B. 



J Zuntz and Schumburg, Physiologic des Marsches, Berlin, 1901, p. 258. 

 2 Durig, Arch. f. d. ges. Physiol., 1906, 113, p. 263. 



