HEAT 



307 



^ 114. Recoveries (Man) 



In tests now to be considered, excesses of heat develop during 

 physical exercise in hot atmospheres. Thereafter the net rates of 

 heat loss are studied during later recovery indoors, where no solar 

 radiation prevails and the air is cooler (fig. 143). In the first 0.3 

 hour the net loss is slow, heat production probably decelerating 

 gradually ; thereafter load diminishes with time up to 1.0 hour. In 

 other tests, deficits develop during the drinking of ice-water, and 

 other adjustments are occurring initially (fig. 143). 



0.2 



0.8> 



1.0 



0.4 0.6 

 Hours 

 Fig, 143. Heat load (increment in Calories per kilogram of Bo) in relation to 

 time during recovery. Heat loads (increment of rectal temperature x 0.83) were imposed 

 either by walking in the hot desert or by drinking ice water; recovery consisted in 

 resting indoors in an air temperature of 30 to 31° C. Several tests that started with 

 about the same load are averaged, the number of tests included being indicated. Five 

 subjects (A, D, H, K, P). Further data of Adolph ('38), and of Pinson and Adolph 

 ('42). 



The rates of net exchange are clearly related to the diverse heat 

 loads (fig. 144), gain of heat augmenting in deficits and loss aug- 

 menting in excesses. 



In still other tests total exchanges are measured instead of net 

 exchanges. After moderate cooling (fig. 145) the rate of heat pro- 

 duction is no greater than before ; shivering is usually absent. In 

 this and similar tests, therefore, recovery occurs by temporary 

 diminution in rate of heat loss. I draw the same conclusion from 



