Tips for Exercising in the Heat

Exercising in the heat 8-28-14

It’s the dog days of summer—and that means heat. Unfortunately, heat can be risky for people who exercise outdoors. If you’re planning to work out in hot weather, the tips here can help you stay safe.

The danger of working out in high temperatures is that your body can easily overheat. And this is dangerous. At its mildest, getting too hot can lead to heat cramps (painful muscle cramps). At its worst, it can lead to heat stroke (body temp above 104˚), which is a medical emergency. In between these are heat collapse (fainting) and heat exhaustion (high body temp plus symptoms like headaches and vomiting).

Why are heat and exercise such a dangerous combo? For starters, your heart must work double-time. First, it has to pump enough blood to your muscles to keep them moving. But then it must also pump enough blood to your skin, so that sweating can cool the blood and your body. Sometimes your heart may not be able to keep up, which may lead to your losing the ability to cool your body sufficiently with sweating.

On top of the demands on your heart, both exercise and the hot outside air make your body heat up. And if it’s humid as well as hot, then that sweat isn’t evaporating from your skin. Again, this means no cooling system. Plus, if you don’t drink enough fluids, you’ll get dehydrated. And this goes hand in hand with heat illnesses.

To avoid the dangers of exercising in warmer weather, follow these tips:


  • Drink plenty of water. Drink plenty of water before you exercise and every half hour during your work out. Sports drinks may be needed to replace electrolytes lost in sweat if you do intensive workouts over 1 hour.
  • Exercise when it’s cooler. Choose morning or evening hours.
  • Take it down a notch. If it’s warmer and more humid than you are used to, slow your pace and shorten your workout.
  • Monitor the weather. If it’s over 80 degrees and 80 percent humidity or if it feels uncomfortable to you, move your workout indoors.
  • Dress to stay cool. Wear lightweight, loose-fitting clothes. Also, choose light colors. (Dark colors absorb heat.)
  • Know the warning signs and symptoms of heat-related illness.
  • For heat exhaustion these include:
    • Muscle cramps
    • Headache
    • Heavy sweating
    • Weakness
    • Dizziness or lightheadedness (especially with standing)
    • Fainting
    • Cold, moist skin
    • Fast, weak pulse

If you have any heat exhaustion symptoms, stop your workout and get somewhere cool. Drink fluids and cool yourself down by applying cold water or ice to your skin. If you don’t feel better within 30 minutes, get medical help.

  • For heat stroke, the warning signs and symptoms include:
    • Warm, dry skin with no sweating
    • Confusion or irritability
    • Heart rhythm problems
    • Low blood pressure
    • Fast pulse
    • Fainting
    • Vision problems
    • Headache
    • Nausea and vomiting
    • Fatigue


Heat stroke is a medical emergency. If you have any heat stroke signs and symptoms—or see someone else experiencing these signs—call 911 immediately. Treatment delays can lead to permanent brain and kidney damage.

Use active cooling measures while waiting for medical assistance. This includes moving to a cooler location, removing extra layers of clothes, and applying cold water, ice and/or a cool, wet cloth behind your neck, on your forehead, at the creases between your lower abdomen and upper thighs, and/or under your armpits.

Do not eat or drink anything until your health care provider tells you it is safe to do so as this may make some signs and symptoms—including nausea and vomiting—worse.





Primary Author: Virginia Wilke (08/22/14)

Last Clinical Reviewer: L. Fraley (8/25/14)

Last Review and Approval: S. Ivie (08/28/14)

Date of Last Review:




American Heart Association. (2013). Top 5 tips to staying cool during your summer workout. Retrieved August 21, 2014, from

Cleveland Clinic. (2013). Exercise & the heat. Retrieved August 21, 2014, from

González-Alonso, J., Crandall, C. G., & Johnson, J. M. (2008). The cardiovascular challenge of exercising in the heat. The Journal of Physiology, 586(1), 45–53. doi: 10.1113/jphysiol.2007.142158

Mayo Clinic. (2014). Heat and exercise: Keeping cool in hot weather. Retrieved August 21, 2014, from