Limb vs trunk sweat gland recruitment patterns during exercise in humans

The purpose of this study was to examine the sweat gland recruitment pattern, on multiple trunk and limb sites, during exercise. Nineteen male volunteers performed 30 min of exercise on a cycle ergometer at approx. 25, 50 and 75% of their maximal oxygen uptake. The number of active sweat glands (per cm(2)) was determined immediately following each exercise bout at the following six sites: left triceps, chest, back, forearm, thigh and calf. The data showed that increases in rectal temperature during exercise resulted in a linear increase in the absolute number of active sweat glands recruited at all six sites (r=0.60-0.80). However, on a percentage basis, the limb sites increased proportionally more (300-600% increase) than the trunk sites (100-200% increase) with increases in rectal temperature. These data suggest that the absolute number of sweat glands recruited, on both the trunk and the limbs, increases in a linear manner with increases in rectal temperature during exercise. However, on a proportional basis, sweat gland recruitment on the limbs is greater than that found on the trunk during progressive exercise.