5 Smart Ways to Exercise in the Heat

Whether you're riding your bike or taking a swim, here's how to stay safe during your summer workouts.

Medically reviewed in October 2021

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Long summer days give us plenty of time to exercise outside after work (or before work, for you early risers). And those summer bike rides, trail runs and laps in the pool are extra healthy: research shows that outdoor workouts can reduce stress and boost mood better than indoor ones. But physical activity in summer heat also has some risks, including overheating and dehydration. So while you’re out there working up a sweat, remember these tips for staying safe.

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Drink Early and Often

This one may seem obvious, but be sure to drink plenty of water when you exercise outside. Experts recommend 14 to 22 ounces of cold water two hours before you get started, and 6 to 12 ounces for every 15 to 20 minutes of exercise.

You want to avoid dehydration, which does a lot more than make you thirsty; it can cause fatigue, crankiness and brain fog. It can even lead to heat exhaustion—when your body overheats—and heatstroke, an emergency situation where your body temperature spikes to 104°F or more. Heat stroke can damage your brain and other organs and may be fatal.

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Start Out Slow

Stick to shorter, easier workouts in the beginning of summer to acclimate your body to higher temps. This will build up your tolerance for spending more time outdoors and keep you from being wiped out after exercising. “Progressive training in the heat prompts certain physiological changes that reduce the risk of heat illness and help you perform better,” says Michael Bergeron, PhD, a Fellow of the American College of Sports Medicine.

On particularly hot days, try moving your workout to the morning or evening, to avoid the midday sun and temperatures. Exercise with a buddy when you can, so you can monitor each other's condition throughout your activities.

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Use a Shot Glass

Make sure to slather on the SPF (guys, don’t skip this step) to reduce the risk of painful sunburns now and skin cancer down the road. Experts recommend using a full ounce—about the amount that fits in a shot glass—to cover your face and all exposed areas of your body. Apply sunblock (SPF 15 or higher) at least 20 minutes before you go outside, and reapply every two hours while you’re working up a sweat.

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Be a Smart Dresser

Cotton t-shirts may be comfy, but because they absorb moisture they aren’t a good choice for summer workouts—not even long walks. (Who wants a sweaty shirt?) Choose clothes that are light-colored, breathable, and designed specifically for the heat. They’re generally made of a cotton/polyester blend that helps to wick sweat away from your skin.

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Know These Warning Signs

Overexertion in the heat can lead to heat cramps—an early sign of heat exhaustion that can lead to heatstroke. Keep an eye out for these signs of heat exhaustion:

  • Cool, clammy skin
  • Heavy sweating
  • Headache
  • Nausea
  • Vomiting
  • Weakness
  • Rapid heartbeat
  • Dizziness
  • A feeling that you might faint
  • Dark urine

If you start to experience these symptoms while you’re exercising outside this summer, stop what you’re doing and head for the shade or indoors. Drink some water and change into clothes that are cool and wet. If your symptoms persist, seek medical attention.

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