How to Exercise in the Heat

It's turning out to be a really hot summer, so make sure you take the proper precautions when exercising in the heat.

By Emily Main


Excercise Outside During HeatStay Healthy and Enjoy the Great Outdoors

• Weigh yourself before and after your workouts. The key to staying hydrated is to match your fluid intake with your sweat loss, he says. "The best way to do that is to weigh yourself before and after your workout and see how much water is lost," he says. One pound of weight difference means you lost about 16 ounces of water.

• Hydrate before your workout, and avoid the sprinklers. Running through a sprinkler or biking past a gushing hydrant may feel good, but it doesn't really cool you off. "Getting fluid inside you is what helps with thermal regulation," Karp says. Drinking water while you exercise is essential, but it's even better to hydrate before you start, he says, because it increases your body's ability to maintain a proper temperature and can help your heart maintain a steady pace so you won't feel like you're exerting more effort than you really are.

• Try glycerol. It sounds like some new pharma drug, but it's really something you add to your drinks that helps your kidneys retain water, which in turn helps your body stay cool, says Karp; the idea is similar to the way that sodium functions in sports drinks like Gatorade. He recommends drinking a 20 percent glycerol solution (you can find them where vitamins and supplements are sold) no sooner than about 30 minutes before you exercise, since it doesn't always sit well on people's stomachs.

• Get used to the heat first. Karp says it's important to acclimate yourself to the heat with less-intense exercise before heading out for your usual workout. Giving your body time to adjust lowers the stress on your heart and can reduce the amount you sweat. Two weeks is usually enough for most people get acclimated, Karp says, and you should do it in increments. "If you're used to exercising 30 minutes at a time, cut that by a third and then slowly increase," he says. Exercise for 10 minutes outside for the first few workouts, then add another 10 after a few outdoor sessions. If you're just starting an exercise program, on the other hand, stay in the gym to start with and begin exercising outdoors only after you've reached a decent fitness level, says Karp.

• Stick to morning workouts. "Exercise performance actually peaks in the late afternoon," Karp says, "but when you add the stress of heat, that changes things." Research has shown that cool morning air boosts your endurance more so than trying to work out after the sun goes down at night, he adds.

• Invest in synthetics. You'll do yourself a favor by investing in sweat-wicking synthetic shirts rather than reaching for that old cotton T-shirt, which traps sweat next to your skin and doesn't allow it to evaporate, he says. Just be sure to avoid synthetic clothes treated with antibacterial chemicals or silver nanoparticles, both of which have iffy health effects and damage the environment when you toss them in the washing machine.

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