Unveiled, the eve tale of sweat

That question, which has figured in many an antiperspirant commercial, has received surprisingly little scientific scrutiny. But a new study published in Experimental Physiology provides persuasive evidence that women do sweat copiously during exercise.

But fit women seem to sweat differently than unfit people of either sex, and quite differently than fit men, a fact that has implications for sports performance. It also may have some bearing on what it has meant, since prehistory, to be female.

For the study, researchers at Osaka International University and Kobe University in Japan recruited a pool of trained athletes, male and female, as well as an age- and gender-matched group of untrained volunteers. The men and women in the two groups were similar in terms of weight. All of the volunteers rode stationary bikes in a physiology lab heated to a balmy 86 degrees. The beginning of the hourlong session was leisurely; the pedalling intensity was only about 30 per cent of each volunteer’s maximal oxygen capacity (VO2max). Then it became tougher, rising to 50 per cent of each rider’s VO2 max, while the final 20 minutes required that the riders work at a strenuous 65 per cent of his or her VO2 max.

Throughout, researchers monitored how much perspiration the cyclists were producing on their foreheads, chests, backs, forearms and thighs. The researchers also determined how many sweat glands were active during each rider’s session. A person’s overall sweat rate depends on how many sweat glands his or her body activates and how much sweat is excreted at each gland.

The fit men, unsurprisingly, perspired the most, significantly more than the fit women, especially during the more intense exercise. But the athletic men weren’t using more sweat glands. The fit women had just as many glands active and pumping; they produced less sweat from each gland.

Unfit perspires the least

Meanwhile, the unfit women, by a wide margin, perspired the least, especially during the strenuous cycling, and became physiologically hotter — their core temperatures rising notably — before they began to sweat at full capacity.

These results, the scientists concluded, “revealed a sex difference in the effects of physical training on the sweating response” and, just as important, “a sex difference” in the “the control of sweating rate to an increase in exercise intensity.” In other words, the women, whether fit or not, were less adept of ridding themselves of body heat by drenching themselves in sweat.