How to Exercise In the Heat

Learn how to keep cool when you’re exercising in hot conditions.

Ben Greenfield
4-minute read
Episode #60

If you tuned into the recent New York City Triathlon, you may heard that there were many heat-related illnesses during the race, and even one tragic death. During the 2007 Chicago Marathon, runners were rerouted to a city park and instructed to stop running, since the heat was too intense to ensure runner safety. But even if you don’t plan on doing a triathlon or marathon in hot weather, a high temperature outside or in the gym can make exercise uncomfortable, inhibit performance, cause dehydration, and leave you feeling literally and figuratively under the weather. In this article, you’ll learn how to keep cool when you’re exercising in hot conditions.

What Happens to Your Body in the Heat

As soon as you get into the heat and begin to exercise, you force your body to circulate blood out to the skin, where it can be cooled. But this circulation to your skin can draw precious, oxygen-delivering blood away from your working muscles, and also lower the amount of blood your heart can pump with each beat. In addition, you’re also losing blood volume as you lose fluid in sweat, and this places additional demand on an already stressed heart.

As blood becomes a precious commodity and your heart is forced to work harder, your heart rate goes uncomfortably high, your breathing becomes more difficult, your blood pressure drops, and your core temperature rises. Eventually, you reach a point where your body sends a message to your brain to stop, and at that point, exercise goes from being uncomfortable and difficult, to simply impossible.

How to Stay Cool in the Heat

So what can you do about this loss of blood volume and increase in body temperature? Here are 5 solutions:

1) Train your body to maintain a higher blood volume. Also known as “heat acclimation,” the process of training your body to have more blood involves a combination of consistent training and heat exposure. Gradual exposure to exercising in hot conditions is one of the best ways to do train your body to heat acclimation. For example, start with 10-20 minutes of jogging, bicycling, or brisk walking in the afternoon heat, and add just 2-5 minutes each day as the heat becomes more tolerable. When you combine this with drinking big gulps of water whenever you begin to get thirsty, your body learns to increase blood volume to help you cool.

2) Increase your sweat rate.  Did you know that very fit individuals and athletes produce more sweat? This is an enhanced cooling mechanism that is developed during heat exposure. I’ve personally found that a very good method for teaching your body to sweat more is to visit the steam room or sauna and simply sit for 10-20 minutes. Two to three weeks before I’m about to do a triathlon in hot weather, I’ll increase my steam room or sauna time up to 45 minutes, but this can be very taxing to your body, so be careful!

3) Decrease the amount of salt produced in your sweat.  Not only do you sweat more as you get fitter and increase heat exposure, but you also lose less salt in your sweat! Your body actually learns to hold on to the precious sodium that you need for muscle contractions. While gradually becoming accustomed to hot exercise conditions, your body will automatically decrease the salt you produce in your sweat. You can also try to limit sodium intake during exercise. As you learn to live and exercise with lower salt intake, your body begins to excrete less salt.


About the Author

Ben Greenfield

Ben Greenfield received bachelor’s and master’s degrees from University of Idaho in sports science and exercise physiology; personal training and strength and conditioning certifications from the National Strength and Conditioning Association (NSCA); a sports nutrition certification from the International Society of Sports Nutrition (ISSN), an advanced bicycle fitting certification from Serotta. He has over 11 years’ experience in coaching professional, collegiate, and recreational athletes from all sports, and as helped hundreds of clients achieve weight loss and fitness success.