Esterhaus, M. P., Buono, M. J., Fossiter, H. B., & Kolkhorst, F. W. (2011). Effects of exercise intensity on sweat-rate kinetics. Medicine and Science in Sports and Exercise, 43(5). Supplement abstract 550.

This study modeled the sweat rate response at varying exercise intensities. Ss (N = 8) completed one bout of cycle ergometry (18-25 minutes) at four intensities: 60%, 80%, and 100% lactate threshold, and at 30% of the delta between lactate threshold and VO2max. Forearm sweat responses were measured during exercise with a ventilated sweat capsule using resistance hygrometry. Changes in relative humidity in the sweat capsule were recorded in 5-second intervals and converted to a sweat rate. The sweat response was modeled using nonlinear regression analysis. The effects of exercise intensity on the sweat rate amplitude, time delay, time constant, and initial rate of change (amplitude/time constant) were examined.

There were significant main effects for the sweat rate amplitude, time delay, and initial rate of change, but not for the time constant. Sweat rate amplitude increased with exercise intensity accompanied by a decrease in the time delay. The initial rate of change in sweat rate increased with intensity up to the lactate threshold, although there were no further changes beyond that point.

Implication. Sweating occurs sooner and in greater amounts as exercise intensity increases. There appears to be an upper limit to the rate of change in the sweat rate, which occurs in proximity to the lactate threshold.

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