Variations in Metabolism. 



253 



rate of 2.7 miles per hour. The results of the comparisons expressed in terms 

 of the metabolism when sitting quietly are given in table 106. 



While the figures presented in table 106 are rough approximations of the 

 variations in metabolism due to changes in muscular activity, they must not be 

 taken as indicative of the exact transformations measured on any given in- 

 dividual or on any uniform set of individuals, consequently the differences in 

 the percentages in the three factors carbon dioxide, oxygen, and heat are not 

 as significant as they would otherwise appear. The fact that during very 

 severe muscular exercise there is an increase of 616 per cent in the carbon 

 dioxide and but 573 per cent in the heat does not represent the true condition. 

 As a matter of fact, as will be seen in the preceding discussion, the experiments 

 during very severe muscular work were made on one subject, and variations in 

 diet and storage of glycogen could not be taken into consideration in experi- 

 ments of so short a duration. The values in this table are to be taken, there- 

 fore, as indicating: onlv in a general way the differences of the different factors 

 of metabolism under different conditions of muscular activity. The experi- 

 ments were not designed to be made on constant diet and with absolutely con- 

 stant muscular activity, and hence the true comparisons between the three 

 factors can not properly be made. Of special significance is the fact that 

 during severe, exhausting muscular work, almost at the limit of human endur- 

 ance, the metabolism may be from 700 to 800 per cent of the resting metabo- 

 lism when sitting. During sleep the metabolism falls to not far from 75 per 

 cent of the value when at rest and sitting quietly. 



VALUES FOR THE METABOLISM DURING DIFFERENT ACTIVITIES AS COMPARED 



WITH SITTING. 



From the large number of experiments when the subject was at rest and 

 sitting or sleeping, we have certain definitely established values for the carbon- 

 dioxide exhalation, oxygen absorption, and heat production. From the per- 

 centages given in table 106 it is possible to compute the probable carbon-dioxide 

 exhalation, oxygen absorption, and heat production of individuals standing and 

 during very severe muscular exercise. These values have been computed and 

 are given in table 107. 



Table 107. Amounts of carbon dioxide eliminated, oxygen absorbed, and 



heat produced during various activities as calculated using 



the results " awake, sitting up " as standard. 



[Amounts per hour.] 



1 Average body-weight 66.6 kilograms. 2 Average body-weight 64.5 kilograms. 



