MILD OVERCOOLING INCREASES ENERGY-EXPENDITURE DURING ENDURANCE EXERCISE

Intensive cooling has been shown to increase energy expenditure (EE) d uring work as well as to decrease physical performance. Two different levels of moderate cooling (10 degrees C vs 15 degrees C) were studied during light endurance exercise in order to examine the effect of the increased heat loss on EE. Twelve subjects performed a 90-min low int ensity exercise (100 W) on a cycle ergometer, wearing a water-cooled c alorimeter suit for controlled cooling. The lower temperature resulted in a 4.3+/-3.8% (mean+/-SD) higher EE, increased total heat loss and lowered skin temperatures. No differences in central core body tempera ture, heart rate or respiratory quotient (RQ) were recorded. There was a relation between differences in the rate of heat loss and the corre sponding increase in EE. Even a small increase in cooling during endur ance exercise increased EE which may be a relevant problem in winter s ports.