July 01, 2025
Thom Carroll/For PhillyVoice
The heat can take a toll on people who exercise outdoors. There are several precautions and adjustments that people should take, including wearing proper clothing, drinking plenty of fluids and avoiding afternoon workouts.
Enduring the heat waves that inevitably come every summer is tough. That's particularly true for people who aim to stay active by exercising outdoors despite the high temperatures.
Doing so requires a few precautions and some adjustments. Here are a few tips to help people who insist on working out in the heat.
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Make sure to regularly apply sunscreen and wear lightweight clothing with moisture-wicking material and maybe even a hat, too.
"The head has a large body surface area for cooling, and a hat provides shade so that area stays cool," Dr. Matt Leonard, an emergency physician at Johns Hopkins' Suburban Hospital," told NPR in 2023.
Plus, wearing sunscreen helps prevent skin cancer. "That's a great longer-term benefit," Leonard said.
Consuming fluids throughout the heat is key.
The average person should drink eight glasses of non-alcoholic, non-caffeinated beverages, according to The University of Colorado Hospital in Denver. Warm-weather exercise only increases that need. The hospital advises people to drink 2-3 cups of fluid two hours before working out in the heat, and then another cup 5-10 minutes beforehand. During workouts, people should drink one cup every 15-20 minutes.
Be weary of over-hydrating and feeling bloated, however. The stomach only can empty about 1 quart of fluid per hour during exercise.
During hot days, it's best to exercise when the temperature is at its coolest. The American Heart Association advises people to avoid outdoor exercise during the early afternoon. Temperatures generally peak from noon to 3 p.m. The coolest times to exercise during the summer are often before 9 a.m. or after 7 p.m.
Jumping into an intense workout may feel like a great start toward achieving one's fitness goals, but when it's very hot out, that's not best plan of action.
Instead, people should slowly ramp up outdoor workouts until their body fully acclimates to regularly exercising in the heat. The University of Miami's Health Collective recommends reducing the length or intensity — or both — of initial outdoor workouts until the body has acclimated to the temperature.
When exercising in the heat, it's critical to be aware of the signs of heat exhaustion. They include excessive sweating, dizziness, headaches, muscle cramps, nausea and rapid heartbeat.
Instead of pounding the pavement as a runner, consider swimming as an exercise alternative, if you have access to a pool. Swimming is a full-body workout that has the immediate benefit of cooling you off in the heat, too.
Desperate times may call for desperate measures when it comes to the heat. Placing a cold washcloth onto one's neck, or wearing underwear that has spent several hours in the freezer — a more outside-the-box measure — are ways to cool off during the course of a heated workout.
But Ashley Willmott, a physiologist at Anglia Ruskin University in England, told the New York Times in 2021 that those techniques can be risky, because the effects are short-term. "We sometimes see people cool before exercise, feel great, then head out too fast or hard," he said.
It may be obvious, but it's true. If the temperatures are too extreme for your regular outdoor routine, consider exercising indoors for the day. Vanderbilt University Medical Center suggests checking out a class at a gym, where the air conditioning has been cranked up.
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