by GRETCHEN REYNOLDS
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.
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As someone becomes more fit, his or her body begins to sweat at a lower body temperature. This is important, because “the body has a critical core temperature,” Dr. Cable said, which occurs at about 104 degrees, after which the brain simply “shuts down the motor cortex.” Unbidden, your legs stop churning and you curl up on the sidewalk until your core temperature drops (or a kind passerby calls 911). Sweating delays the onset of this critical heat buildup by dissipating the excess heat through evaporation. If you start to sweat at a lower temperature and increase your sweating rate as you get hotter during hard exercise, you’re less likely to reach the critical temperature.
Scientists learned all that long ago. But they have yet to explain why women, even the fittest, don’t sweat as much as men, especially when they exercise at a high intensity.
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