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Is It Dangerous to Run in the Heat?

Reviewed by: Mary L. Gavin, MD

I live in Florida, so it's really hot all the time. Is it dangerous to run outside in the heat? Will I burn more calories outside or inside on a treadmill?

Yes, it can be dangerous to run outside in the heat — particularly in regions like Florida, where the humidity can get pretty high. As temperature and humidity rise, it becomes harder for your body to cool itself down, which can lead to heat-related illnesses such as heat cramps, heat exhaustion, and heat stroke — a medical emergency. Dehydration increases the risk of heat-related illnesses.

When you go running, be sure to wear light clothing, stick to the shade, and drink water every 15 minutes. Symptoms of heat-related illness include muscle cramps, weakness, nausea, and vomiting. If you experience any of these, stop your workout immediately, cool off, and hydrate.

If you're an outdoor person in warmer climates, your best bet is to run in the morning or evening, when temperatures are cooler. But even the early-morning hours in the Sunshine State may be too hot for running. On hot days, consider moving your workout inside. You tend to burn more calories by running outside than on a treadmill, but you can always adjust the incline on the treadmill to increase the intensity of your workout. The scenery may not be as nice, but working out in a gym has its advantages, and you can add a little variety to your cardio routine by trying out other equipment, like the stair stepper or elliptical machine.

*Names have been changed to protect user privacy.

Reviewed by: Mary L. Gavin, MD
Date reviewed: July 2018