Habib, C. M., Canine, K. M., Bothorel, B., Trone, D. W., & Vurbeff, G. K. (1997). Effect of exercise mode on cooling and heat strain. Medicine and Science in Sports and Exercise, 29(5), Supplement abstract 554.

The effects of exercise mode on heat strain when whole-body cooling was provided by a liquid cooling undergarment was examined.

Males (N = 8) exercised for 120 min in a hot environment (49 degrees Celsius) while dressed in a chemical protective overgarment. The following activities were performed: arm-cranking with no cooling, arm-cranking with cooling, treadmill with cooling, and treadmill with no cooling. Each test consisted of repeated intervals of 20 min exercise followed by 10 min rest.

Results showed that heart rate was higher with upper-body exercise than with lower-body exercise and that thermal strain was unrelated to the mode of exercise when no cooling was provided. Heart rate was higher for upper-body work when cooling was provided.

Greater heat extraction was required to maintain thermal balance during lower-body exercise than during upper-body exercise when work rates were matched.

Implication. Greater amounts of heat will be generated with lower-body work than with upper-body work and thus, natural or artificial cooling will need to be greater for those forms of exercise. Fluid loss is likely to be greater with lower-body work.

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