Your Body on Sweat
When you do any physical activity, your temperature rises, triggering your brain to release the chemical acetylcholine, which then travels down your spinal cord and into the millions of eccrine sweat glands all over your body. "Acetylcholine prompts the eccrine glands to pull water and salt from the blood to the skin's surface to help cool us down," says Purvisha Patel, MD, a dermatologist for Advanced Dermatology and Skin Cancer Associates in Memphis.
Apocrine glands, the other type of sweat glands we have, are concentrated in areas abundant in hair follicles, like the armpits, chest and groin. They're activated by anxiety and stress. These glands are primarily the ones that make you smell less than fresh. "The apocrine glands secrete an oily substance that, when combined with the bacteria already on your skin, produces odor," says Dee Anna Glaser, MD, a professor of dermatology at the Saint Louis University School of Medicine. "Likewise, when you're sweaty from an exercise session, your skin becomes the moist environment where bacteria grow. It's the bacteria, not the sweat, that cause odor and clog pores, which can lead to breakouts."
How much we sweat is mostly due to genetics, says Heather Woolery-Lloyd, MD, a dermatologist and the director of ethnic skin care at the University of Miami. Other determining factors include how athletic we are and how conditioned we are to heat. Studies have found that elite athletes are more efficient than the rest of us at cooling their bodies through perspiration. "The fitter you are, the faster your brain triggers sweat production," says Candace Spann, MD, a dermatologist in Las Vegas. That way, your body gets rid of excess heat before your internal temperature reaches the this-is-way-too-hot mark, which allows you to work out longer and harder.
Where you live also plays a role in perspiration: People who exercise in tropical temperatures sweat more than people who work out in more temperate locales. "After acclimatizing to the heat, we perspire more and at a faster rate," Dr. Spann says. That's why it's essential to drink plenty of water when you work out, because you can lose up to three liters' worth in an hour on a hot day. Weigh yourself before you exercise and again afterward, and sip an extra 16 ounces for every pound lost.
How to Stop Dripping
Chill out. To put an end to post-exercise perspiration, the key is to quickly reduce your body temperature. Start by draping a cold, wet towel around your neck. Because your blood vessels there are close to the surface of your skin, they'll constrict quickly, sending a signal to your brain to lower your body temperature, Dr. Patel says. Then, get out of your workout gear as fast as possible. Rather than jumping into the shower, run cold water over your wrists and hands for a few minutes, which will make your core temp drop more rapidly than a lukewarm shower will, says George Havenith, PhD, a human-thermoregulation expert at Loughborough University. If you can't do that, drinking a glass of ice water or even leaning against a metal locker will help. When you do take a shower, make sure it's tepid; hot water will simply keep your body temperature raised, meaning you'll resume sweating as soon as you step out. No time to bathe? Do a quick cleanup with body wipes, then spritz on a minty body spray and pop a peppermint. The menthol in them activates receptors in your skin, which makes you feel cool.
Put on the right sweat stopper. Antiperspirants contain aluminum, which plugs sweat glands to block perspiration. Most products are 12 to 20 percent aluminum; those labeled "clinical strength" are closer to the 20 percent mark. Don't buy into the myth that you can get breast cancer from your deodorant; after reviewing numerous studies on the subject, the American Cancer society says that no clear link has been made at this time. For the best results, apply antiperspirant in the evening, Dr. Glaser suggests. "Sweat glands are least active at night, so the ingredients in the antiperspirant will have the opportunity to work," she explains. "In addition, regularly exfoliating and moisturizing under your arms will minimize irritation and maximize the antiperspirant's effectiveness," says Ellen Marmur, MD, a dermatologist in New York City. Deodorants, on the other hand, mask the odor of sweat, but unlike antiperspirants, they don't control wetness. A combination antiperspirant and deodorant will keep you dry and sweet smelling.
Stay cool down below. If you suffer from crotch sweat, be sure to wear cotton panties and moisture-wicking workout clothes. Trimming or waxing your bikini area can also help reduce sweat there, as can sprinkling an absorbent, talc-free powder into your underwear.
Pick your clothes carefully. Breathable fabrics like linen and cotton will help sweat evaporate easily, and darker colors can mask any sweat stains during, say, an important meeting with your boss, Dr. Woolery-Lloyd says. Keep your shoes dry and odor-free by dusting them with powder and allowing them to sit a few days between wearings.
Get help. Approximately 3 percent of the population suffers from hyperhidrosis, or excessive sweating, Dr. Glaser says. If you're in this group, ask your doc about such options as prescription antiperspirant, which contains around 25 percent aluminum for better sweat control; Botox injections, which stop sweat glands from making excessive perspiration for about seven months and cost about $1,000; and a microwave treatment called Miradry, which can permanently minimize perspiring by eliminating sweat glands entirely. It runs about $3,000.
Surprising Causes of Sweat
Your snacks. Caffeine raises your body temperature, so your afternoon latte may be making you perspire, even if it's iced. Heavy foods can have the same effect, because your body has to work hard to digest them, raising your core temperature. Stick to decaffeinated drinks and fruits and salads, especially on hot days.
Your meds. Nonsteroidal anti-inflammatory drugs (NSAIDs) and some other medications can increase sweating, especially as you get older, says Kenneth Mark, MD, a clinical assistant professor in the Department of Dermatology at New York University. If you perspire frequently, review any drugs you're taking with your doctor.
Your significant other. If he gives you sweaty palms, that's a good thing. You perspire more when you're around someone you're attracted to, because you're in a state of adrenaline-pumping physiological arousal.