Why is exercising on a hot day so dangerous?

2025-06-25 17:02:00, Shëndeti CNA

Extreme heat makes it especially difficult to cool your body, so you need to be extra careful if you exercise or play sports when temperatures are high outside.

Your brain tries to keep your body at 37 degrees, and it does so in part by causing you to sweat. When sweat dries, it removes heat from your body's surface.

When sweat can't do its job because your body is generating too much heat or it's too hot, you're at risk of becoming dehydrated or even contracting a heat-related illness, such as heat exhaustion or heat stroke.

Bharat Venkat, an associate professor at UCLA and director of the UCLA Heat Lab, says heat can affect the entire body. “We’ll often talk about heat cramps. We’ll talk about heat exhaustion. We’ll talk about heat stroke,” he said. “But it’s actually much broader than that. Heat can really affect every system in our body, our hearts, our lungs.”

The higher the temperature, the harder it is for the body to stay cool, but humidity also plays a big role. High humidity makes the air feel hotter than the temperature because it makes sweating less effective.

The heat index, which takes humidity into account and is included in many weather forecasts, gives a sense of how hot it actually feels and what is dangerous during prolonged exposure or strenuous activity.

The National Oceanic and Atmospheric Administration says people should start exercising “caution” when the heat index reaches 80 to 90 degrees and “extreme caution” from 90 to 103 degrees. It labels anything above 103 as “danger” or “extreme danger,” the Associated Press reports.

If you want to exercise despite the high temperatures, here are some tips:

-Schedule exercise and outdoor activities during the cooler parts of the day.

-Try to exercise in the shade as much as possible.

-Take frequent breaks.

-Drink plenty of fluids and limit drinks that are high in sugar, caffeine, and alcohol. Don't wait until you're thirsty to drink more.

-Do exercises with someone so you can check in on each other or join a teammate.

If you begin to feel any of these symptoms, stop exercising, move to a cool place, and seek medical attention:

-Muscle pain or muscle weakness

-Difficulty breathing

-Dizziness

-Headache

-Mixed

A common heat-related illness is heat exhaustion, which can be characterized by rapid heartbeat, rapid breathing, headache, nausea, and weakness or muscle cramps.

It can develop into the more serious heat stroke, when your body can no longer control its temperature. Symptoms include confusion or slurred speech, seizures, or even loss of consciousness.

Heat also increases the risk of a rare condition called rhabdomyolysis, which causes rapid muscle breakdown./ CNA