If you’re an avid outdoor exerciser, there’s no need to let the summer heat or scorching sun sabotage your fitness habits altogether—but you do need to make a few tweaks to stay safe and healthy (read: avoid heat exhaustion, dehydration, muscle cramps, and the like). And this is even more important for groups who may be more sensitive to high heat, like adults over 65 or people on certain medications such as diuretics, beta-blockers, antihistamines, tranquilizers, or antipsychotics, says Alexis C. Colvin, M.D., an orthopedic sports medicine surgeon at Mount Sinai. We asked Dr. Colvin for her top tips on working out safely when it’s really hot, smart ways to tailor your workouts to accommodate a heat wave, and the biggest signs that it’s time to bring your sweat session indoors.
Why You Need to Be More Careful When Exercising in Extreme Heat
“Heat affects the body in a number of ways, including increasing body temperature, increasing heart rate, and increasing blood flow to the skin ([your] blood vessels dilate to increase sweating),” Dr. Colvin says. When it’s super-hot—like, 80 to 90-plus degrees Fahrenheit—your body is more susceptible to heat-related issues, especially when exerting lots of energy from physical activity. Dr. Colvin notes that dehydration, heat cramps, and heat exhaustion are some of the most common conditions related to exercising in hot and/or humid temps.
What is heat exhaustion?
“Heat exhaustion occurs when the body isn’t able to cool itself down, typically due to a combination of physical activity and high temperature (especially with high humidity),” she explains. “When the humidity is high, sweat doesn’t evaporate as readily from your skin, which is the body’s normal cooling mechanism.” Matters are made worse if you’re not properly replenishing the water and electrolytes you’re sweating out (in other words, you’re dehydrated). Some signs and symptoms of heat exhaustion to watch out for, according Dr. Colvin: headache, dizziness, fatigue, nausea, vomiting, cramping, heavy sweating, fast but weak pulse, and/or cold, pale, clammy skin.
How hot is too hot to exercise?
Dr. Colvin says the best way to determine how safe it is to exercise or work vigorously outdoors is the WBGT, or wet bulb globe temperature, which “is a measure of the heat stress in direct sunlight,” according to the National Weather Service, and takes into account “temperature, humidity, wind speed, sun angle, and cloud cover.” This is different from the heat index, but if the WBGT isn’t available for your location, the heat index works, too. “In general, [temperatures] below 70 degrees F have a low risk of heat illness,” Dr. Colvin says. “Caution is recommended when exercising between 80 and 90 degrees F—and extreme caution is advised when the heat index is over 90 degrees F.” If you’re not acclimated to these high temps (and few are), you’ll want to head into an air-conditioned, shady space when it gets into the 90s For those more sensitive groups, you may want to do so even if the heat index is below 80 degree F.
Smart Tips for Safe Workouts in the Heat
Her favorite dynamic warm-up moves to try: jumping jacks, inchworms, butt kicks, jogging with arm circles, lunge with a twist, skaters, and high knees. And some static stretches for cooling down: cat cows, child’s pose, pigeon pose, runner’s lunge, cross-arm and overhead triceps stretch, and doorway pectoral muscle stretch. (Here’s a quick, full-body stretching routine you can do every day.) RELATED: 3 Gentle Stretches for a Stiff Upper Back and Neck Pain Hydration guidelines to follow, according to Dr. Colvin: When doing an activity for less than one hour, water is going to be the ideal drink. But when sweating and exerting energy vigorously in the high heat for anything longer than one hour, drink fluids that contain both carbohydrates and sodium (like sports drinks) to replenish lost glucose and electrolytes. RELATED: 10 Super-Hydrating Drinks That Are Way More Interesting Than a Glass of Water
