6 things you didn't know about sweat
Find out some surprising facts about why, when and how we perspire.
Tue, Oct 04, 2011 at 12:20 PM
Ever heard the old adage that men sweat and women glow? Turns out, the two sexes do sweat differently — just not in the ways you might expect. We spoke to the experts to get the scoop on everything from surprising treatments for excessive sweating to fascinating emotional responses caused by perspiration. Read on for info that will change the way you think about sweat.
1. Your fitness level can affect how much you sweat.
When the water in sweat evaporates on your skin, it cools down your body, which is the whole purpose of sweat — to prevent overheating. According to the International Hyperhidrosis Society, athletes sweat more than regular people because their bodies have become adept at keeping cool by increasing the amount they sweat. That same study published in the Journal of Experimental Physiology also found that the core body temperature in unfit women, who perspired the least, had to rise significantly more for them to sweat at maximum capacity.
2. Men sweat more than women.
In general, males really do produce more sweat than females — approximately four times more per day, according to David Pariser, MD, founding member and secretary of the International Hyperhidrosis Society. While both sexes have about the same number of sweat glands, Dr. Pariser says that, because men are larger, they have more surface area to cool off, not to mention the hormonal variations that cause them to sweat more. A study published in the Journal of Experimental Physiology found that when physically fit men and women exercised intensely, the men produced more sweat — even though both sexes had the same number of active sweat glands. The study also followed unfit men and women and found that the unfit women perspired significantly less than their male counterparts.
3. Not all sweat is created equal.
Though you might assume all perspiration is the same, there are actually two different types of sweat, according to Hratch Karamanoukian, MD, director of the Center for Excessive Sweating. Eccrine sweat glands are responsible for producing "water sweat," which is composed mostly of water and salt. These glands are found all over the body, but are usually more concentrated on the hands, feet and face, and work to cool off your body, whether due to exercising or hot temperatures. Apocrine sweat glands, on the other hand, produce much less sweat, are located where hair follicles are (such as in your armpits) and are responsible for odor-containing sweat. While the purpose of the apocrine glands is unclear, they are believed to be "scent" glands, according to the American Academy of Dermatology.
4. Sweat may give off stress signals.
Think your facial expressions, body language and voice are the only ways to convey how you're feeling? If your sweating is caused by stress, you may unknowingly be sending tension to those around you. "When you're stressed, you sweat from both the odor sweat glands and the water sweat glands. But the [odor sweat glands] get a head start," says Dr. Pariser — which means that as soon as you start to feel stressed, you could be emitting a scent that's detectable by others. A study published in the journal PLoS One showed changes in brain activity when participants were exposed to the sweat of other people in an emotionally tense situation — in this study's case, skydivers. The participants had a subsequent chemical reaction to the sweat, which caused them to become more alert to potential threats, and display higher levels of vigilance.
5. There's a name for excessive sweating.
Think you perspire more than the average person? You very well might. According to Dr. Karamanoukian, anywhere from 1 percent to 3 percent of the population has hyperhidrosis, a condition characterized by excessive sweating due to over-active sweat glands. Though the exact cause of hyperhidrosis is unknown, the symptoms usually begin around adolescence. "These people will sweat for no apparent reason; it makes no difference if they're in a cool room and aren't feeling any stress. The areas most affected by hyperhidrosis are the underarms, hands, feet and face." Hyperhidrosis can be treated with a variety of procedures. Botox, for instance, which is largely known for smoothing wrinkles, has also been approved by the U.S. Food and Drug Administration (FDA) to treat excessive underarm sweating. "After an injection, those sweat glands will stop producing sweat for three to six months," says Dr. Karamanoukian. Other options include clinical strength antiperspirants, liposuction or FDA-approved electromagnetic treatments. If you think you suffer from excessive sweating, be sure to visit your doctor to rule out any underlying causes.
6. The best time to apply antiperspirant is at night.
Antiperspirants usually contain aluminum or zirconian as active ingredients, both of which, upon contact with water, will physically clog the sweat glands and stop them from producing sweat. "Antiperspirants are most effective when applied to very dry skin," says Dr. Pariser. "If you apply them in the morning right before you head out, or right after you get out of the shower, you'll likely already be sweating or have wet underarms. If the skin's surface is wet, the chemical reaction that forms from the aluminum will happen on the surface of the skin instead of in the pores, preventing the sweat glands from getting blocked." Instead, he recommends applying these products at night when sweat production is at its lowest. Even when you shower the next morning, the antiperspirant will still be effective, since it can last for a few days. Then, after your shower, if you want a scent, you can apply a deodorant for fragrance. Though there are concerns amongst some people that the aluminum salts in antiperspirants may cause Alzheimer's disease or breast cancer, both the Alzheimer's Association and the National Cancer Institute report that no scientific evidence has linked antiperspirants to either disease.
Photos: mikebaird/Flickr, ZUMA Press
This article is reprinted with permission from WomansDay.com.
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