If you’re a dedicated athlete, weather doesn’t stop you from your training and workout routine. But when temperatures turn hot, it’s time to take some extra precautions.
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Physical activity increases your core temperature. So does hot weather. When you combine the two, you risk serious illness.
Your body takes steps to adjust to hot weather by perspiring and expanding your blood vessels. But these cooling strategies may not be enough if you exercise in hot, humid weather.
How heat plus exercise creates illness
Exercising for too long in hot, muggy weather, sweating heavily and not drinking enough fluids can combine to develop heat-related illness, says sports medicine specialist Carly Day, MD.
“Your blood vessels dilate and your heart sends more blood to circulate through your skin as a cooling mechanism,” Dr. Day says. “This leaves less blood for your working muscles and, as a result, your heart pumps faster.”
Your body is under even more stress when the humidity is high, Dr. Day says. “High humidity prevents your sweat from evaporating quickly, so this cooling mechanism becomes less effective against your rising core temperature.”
Watch for hot temps, high humidity
Heat-related illnesses start out mild, but grow worse – and can get serious – if you ignore them. Heat-related illnesses include:
- Heat cramps, which occur when your body becomes dehydrated and lacks electrolytes. Relieve with rest, fluids and gentle stretching or applying ice.
- Heat exhaustion, which happens when you overexert your body for too long with insufficient replenishment of water and electrolytes. Symptoms include fatigue, weakness, light-headedness, nausea, vomiting and profuse sweating. To alleviate symptoms, move to a cool area and remove excess clothing. Cool down with a cold cloth or a cool bath. If symptoms do not improve rapidly, seek emergency medical attention.
- Heat stroke, which results from a complete shutdown of the body’s heat regulation system and leads to increased body temperatures. Symptoms include warm, red, dry skin, lack of sweating, disorientation and unconsciousness. Heat stroke is a life-threatening condition and requires emergency medical attention immediately. Get out of the sun and get into a cool bath immediately while waiting for emergency services to arrive
Preventing heat-related illnesses
There are a number of steps you can take to reduce your risk of heat illnesses, but still keep your exercise routine intact, Dr. Day says.
Fluid replacement is the most important factor in preventing heat illnesses. Drink fluids as much and as often as you can if you exercise for more than 30 minutes. Drink 8 ounces to 12 ounces of water 20 minutes to 30 minutes before you exercise, plus 6 ounces to 12 ounces more every 30 minutes of exercise to prevent dehydration.
You also should be aware of weather conditions, especially the combination of high heat and humidity, Dr. Day says. Try to exercise at cooler times of the day, or reduce the length, intensity and frequency of your sessions.
“If the temperature is above 80 degrees and the humidity is above 80 percent, it’s best to postpone your activity until things cool off,” she says.
Also, it’s best to wear temperature-appropriate clothing, such as a loose-fitting cotton T-shirt, shorts and a brimmed hat, while exercising outside in hot weather. Don’t wear items like rubber suits or long-sleeved sweat suits that prevent evaporation of sweat, because they interfere with your body’s natural cooling system.
“By following these preventive measures, you can more easily – and safely – maintain your performance level and effectiveness,” Dr. Day says.