232 METABOLISM DURING WALKING. 



the quotients in the first few weeks of the series (in the untrained 

 period) usually show higher values for the experiments on Mondays 

 which followed the day of rest on Sunday. (See table 60.) Later in 

 the study, and especially when the work became more intense, this is 

 not apparent, for the later quotients follow no general trend, but are all 

 on a higher level than those when the work of walking was lighter. 

 With this subject it is possible that during the intermission on Sunday 

 there was an accumulation of carbohydrate in the body which was 

 drawn upon during the walking of Monday, thus raising the quotient 

 for that day. If this were the case, the increase in the body carbo- 

 hydrate appears to have been insufficient to supply the energy re- 

 quired to keep it at this higher level on the following days; accordingly 

 theie was a subsequent return of the quotient to the previous value. 

 That no difference in the Monday quotients is apparent when the 

 amount of walking became greater may be explained by saying that the 

 increase in the metabolism due to the increase in the work may have 

 been so large that this minor factor was lost sight of. Since our sub- 

 jects were uncontrolled outside of the Laboratory, and, aside from the 

 data regarding the last meal before the experiment, no detailed record 

 was made of the diet, it is possible that the higher quotients on Monday 

 have no special significance in this connection, except to show that 

 some change in diet was made of which we have no knowledge, such as 

 a possible indulgence in candy on the day of rest. 



The absence of definite evidence in our results of the influence of a 

 day of rest, as compared with the results found by the investigators 

 referred to, may be due to a difference in the character of the experi- 

 ments. With Zuntz and Schumburg the subject was carrying a load 

 of approximately 25 kg. 1 while walking on a level at rates from 70 to 

 80 meters per minute. This does not allow a statement in terms of 

 kilogrammeters, but the oxygen consumption was no greater nor as 

 large, in many instances, as found for the subjects W. K. and E. D. B., 

 who were walking up-grade without a load. Their subjects were con- 

 trolled in their diet, while ours, as stated, were unrestrained, except 

 for a 12-hour abstinence from food preceding the experiment. Evi- 

 dently with W. K., and possibly with E. D. B., the work performed on 

 these days was not such as to reduce the store of body carbohydrate 

 to so great an extent that it could not be restored to a normal level 

 during the resting hours of the remainder of the day and night. 



After the writing of this report had been practically completed, the 

 most interesting paper of Krogh and Lindhard, 2 entitled "The relative 

 value of fat and carbohydrate as sources of muscular energy, with 

 appendices on the correlation between standard metabolism and the 

 respiratory quotient during rest and work," was received. The experi- 



J Zuntz and Schumburg, Physiologie des Marsches, Berlin, 1901, p. 249. 

 'Krogh and Lindhard, Biochem. Journ., 1920, 14, p. 290. 



