Regional differences in the effect of exercise intensity on thermoregulatory sweating and cutaneous vasodilation

Abstract

To investigate regional body differences in the effect of exercise intensity on the thermoregulatory sweating response, nine healthy male subjects (23.2 +/- 0.4 year) cycled at 35, 50 and 65% of their maximal O2 uptake (VO2max) for 30 min at an ambient temperature of 28.3 +/- 0.2 degrees C and a relative humidity of 42.6 +/- 2.4%. Local sweating rate (msw) on the forehead, chest, back, forearm and thigh increased significantly with increases in the exercise intensity from 35 to 50% VO2max and from 50 to 65% VO2max (P < 0.05). The mean values for the density of activated sweat glands (ASG) at 50 and 65% VO2max at the five sites were significantly greater than at 35% VO2max. The mean value of the sweat output per gland (SGO) also increased significantly with the increase in exercise intensity (P < 0.05). The patterns of changes in ASG and SGO with an increase in exercise intensity differed from one region of the body to another. Although esophageal temperature (Tes) threshold for the onset of sweating at each site was not altered by exercise intensity, the sensitivity of the sweating response on the forehead increased significantly from 35 to 50 and 65% VO2max (P < 0.05). The threshold for cutaneous vasodilation tend to increase with exercise intensity, although the exercise intensity did not affect the sensitivity (the slope in the relationship Tes vs. percentage of the maximal skin blood flow) at each site. Tes threshold for cutaneous vasodilation on the forearm was significantly higher at 65% VO2max than at either 35 or 50% VO2max, but this was not observed at the other sites, such as on the forehead and chest. These results suggest that the increase in msw seen with an increasing intensity of exercise depends first on ASG, and then on SGO, and the dependence of ASG and SGO on the increase in msw differs for different body sites. In addition, there are regional differences in the Tes threshold for vasodilation in response to an increase in exercise intensity.

Heat Acclimatization in Hot Summer for Ten Weeks Suppress the Sensitivity of Sweating in Response to Iontophoretically-administered Acetylcholine

“…The density and capacity of the sweat glands may differ from one body region to another (Sato and Sato, 1983;Shibasaki et al, 1997;Kondo et al, 1998). However, the forearm sweat glands have widely been used to approximate sweating activity of whole body (Wyndham et al, 1964;Wyndham, 1967;Chen & Elizondo, 1974;Ogawa et al, 1982;Kondo et al, 2001).…”

Modulation of the thermoregulatory sweating response to mild hyperthermia during activation of the muscle metaboreflex in humans

“…Mean skin temperature ( -Tsk) was calculated according to the method of Hardy & Dubois (1938). The SR on the three body sites was measured continuously by the ventilated capsule method (Van Beaumont & Bullard, 1963;Nadel et al 1971;Ogawa, 1975;Yamazaki et al 1994;Kondo et al 1998). Dry nitrogen gas was supplied to three capsules (chest and forearm: 7·06 cmÂ; palm: 1·53 cmÂ) at a rate of 1·5 l min¢ and the humidity of the nitrogen gas flowing out of the capsules was measured using a capacitance hygrometer (HMP 133Y; Vaisala, Finland).…”

Regional microclimate humidity of clothing during light work as a result of the interaction between local sweat production and ventilation

“…The steady rate of sweating differs from one region of the body to another, and there are also regional differences in the degree of increase in sweat rate caused by increasing exercise intensity (Inoue et al, 1991;Inoue et al, 1995;Kondo et al, 1998). Determination of required clothing ventilation and comparison to actual ventilation requires knowledge about regional sweating characteristics and measurement of local ventilation rates.…”