Experimental Physiology –Research Paper: Sex differences in the effects of physical training on sweat gland responses during a graded exercise

Abstract

We assessed sex differences in the sweat gland response to changes in exercise intensity with respect to subjects' physical training status. In total, 37 subjects participated (10 trained and 10 untrained females, and 8 trained and 9 untrained males). Each subject cycled continuously at 35, 50 and 65% of their maximal O 2 uptake (V O 2 max ) for 60 min at an ambient temperature of 30• C and a relative humidity of 45%. The mean local sweating rate (SR) on the forehead, chest, back, forearm and thigh was significantly greater in the trained subjects than in the untrained subjects of both sexes. The degree of the increase in SR with physical training was greater in males than in females at higher levels of exercise intensity. This increase in SR depended primarily on an increase in the sweat output per gland (SGO) in both sexes. However, control of the SR increase with increasing exercise intensity was altered by training in females, i.e. the increase in SR from exercise at 50 to 65%V O 2 max depended only on an increase in SGO in trained females and males and untrained males, but it depended on increases in activated sweat glands and the SGO in untrained females. It was concluded that training improved the sweating response, and a sex difference was observed in the degree of improvement in the sweating response due to physical training. This sex difference became more pronounced with increasing exercise intensity. A sex difference was observed in the control of sweating rate to an increase in exercise intensity, i.e. the maximal activated sweat gland responses of untrained females required a higher body temperature or work intensity than the other groups.

Sweat Rate Measurements After High Intensity Interval Training Using Body Weight

“…Many works 31,32 show that trained individuals present higher economy of movements, that is, they manage to expend fewer calories per time unit compared to untrained people performing tasks with similar absolute intensity.…”

Reply

“…To our knowledge, our recent study (Ichinose-Kuwahara et al 2010) is the first to investigate sweat gland responses from the point of view of the sex difference in the effects of physical training during exercise. We have observed a sex difference in the degree of improvement in the sweating response with physical training.…”

Improved Procedure for Estimating Time-dependent Changes in Local Sweat Rates by Measuring Local Sweat Volumes

“…The sweat production data gathered by 3 series of studies by our group [13,[25][26][27][28] on prepubertal boys and men and women of all ages were comprehensively reanalyzed. In these studies, LSR vc at 4 or 5 body sites were measured continuously by using the ventilated capsule method in the following test conditions: a leg immersion test [27,28] in which 13 young males, 14 older males, 12 young females, and 9 older females immersed their legs in a 42°C stirred water bath for 40 minutes in a chamber maintained at 30°C and 45% RH; a constant intensity exercise test [29,30] in which 6 prepubertal boys, 9 young males, and 5 older males performed 3 different cycling exercises at 35, 50, and 65% VO 2 max for 30 minutes in a seated position at 28°C and 40% RH on separate days; and an incremental exercise test [13] in which 5 trained males, 8 untrained males, 10 trained females, and 9 untrained females performed a continuous graded cycling exercise in the semi-supine position at 35, 50, and 65% VO 2 max for 20 minutes each without rest between intensity changes, at 30°C and 45% RH.…”

“…The ventilated capsule (7.1 cm 2 ) was fixed to the upper section of the left scapula and the local sweat rate (LSR vc ) was measured during the exercise by using the ventilated capsule method [3][4][5][6][7][10][11][12][13]15,16] After the exercises, a part of the absorbent pad was pulled out from each of the tailored pads fixed on the skin. Each absorbent pad was quickly placed, separately, into an impermeable plastic Ziploc bag and weighed with the bag.…”

“…Some studies have focused on the differences in sweat regulation depending on maturation and aging [7][8][9][10][11], sex [12,13], fitness [8,14,15], and heat acclimation [8,16] to elucidate the mechanism underlying thermoregulation. LSR is measured by using a ventilated capsule, and is estimated from the difference in vapor content between the influx and efflux air moving through the capsule at a known flow rate [3][4][5][6][7][10][11][12][13]15,16]. A few small capsules with less than 10 cm 2 in the project areas were generally used, with one capsule per one body part in the majority of previous studies.…”