October 18, 2010

Men Sweat, Women Glow

(Ivanhoe Newswire) -- After women exercise, they generally glow with radiance.  On the other hand, after men exercise, they usually look like he just got out of the pool.  A recent study in Japan looks at the differences between men and women's response to changes in exercise intensity and how men are more effective sweaters in those regards.  Regardless of the difference between sexes, researchers say women 'shouldn't sweat it.'

Researchers that Osaka University and Kobe University asked four groups of subjects (both trained and untrained sexes) to cycle continuously for an hour in a controlled climate with increasing intensity intervals.

The results revealed that men are more efficient at sweating.  While training improves sweating both men and women, the degree of improvement is greater in men, with the difference becoming more pronounced as the level of exercise intensity increases.  Furthermore, the untrained females had the worst sweating response of all requiring a higher body temperature than the other groups -- or work intensity -- to begin sweating.

"It appears that women are at a disadvantage when they need to sweat a lot during exercises, especially in hot conditions," which Yoshimitsu Inoue, the study's coordinator, was quoted as saying.

Men have a higher sweat output than women, in part because testosterone is believed to enhance the sweating response.  Persistent exercise is known to decrease the body's core temperature threshold for the activation of the sweating response, which works to the athlete's advantage by allowing them to perform longer.

The findings in this initial study have heat implications for exercise and heat tolerance in humans, including but not limited to how sexes cope differently with extreme temperatures like heat waves.

However, there may be evolutionary reason why men and women have evolved to sweat differently.  "Women generally have less body fluid than men and may become dehydrated more easily, Inoue explains.  "Therefore the lower sweat loss in women may be an adaptation strategy that attaches importance to survival in a hot environment, while the sweat rate in men may be a strategy for greater efficiency of action or labour."

Future studies will look closer at the relationship between reproductive hormones and the sweating response as well as the effectiveness of different kinds of sweat - sweat that evaporates and cools versus sweat that drops off.  Inoue concludes that "both men and women can acclimate themselves better to heat if they exercise regularly before a heat wave comes."

SOURCE: Experimental Physiology, October 17, 2010