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Heat Stroke and Running: What You Need To Know

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Ah, summer. The season adored by runners for its ample daylight and bearable running temps. And while no-one can deny the joy of running in the sun, it does bring with it some potential risks and issues. Like, for instance, heat stroke.

But what exactly is heat stroke and how common is it? And is there anything you can do to prevent it? Here’s everything you need to know about heat stroke and running.

Heat exhaustion vs. heat stroke

According to Lewis G. Maharam, MD, author of the book Running doc’s guide to healthy running, the symptoms of heat exhaustion and heat stroke are very similar in runners. The latter condition is, however, far more serious and can even be life-threatening. So what are these symptoms? A runner suffering from heat exhaustion will experience one or more of the following:

  • Nausea and, in some cases, vomiting
  • Dizziness
  • Weakness
  • A rapid pulse
  • Warmth
  • Confusion
  • Headache

And while some runners will also stop sweating, this can be tricky to detect when, for example, races have water sponges and spray stations to cool runners down.

Heat exhaustion becomes heat stroke when an athlete’s body temperature reaches 104 degrees or more. This stage is normally associated with a rapid collapse, and it is vital that medical attention be sought as soon as possible. Ice-water immersion and IV-fluids will probably be applied by medical personnel.

So why and how does all of this happen? In short, extreme dehydration and exertion can, through various mechanisms, cause your body to lose its ability to maintain an optimal temperature.

Who’s most at risk?

“Heat stroke … can happen to any type of runner”, says cardiologist Lior Yankelson, M.D., Ph.D. And it appears that the stubborn ones (aren’t we all?) are especially vulnerable. How so? Because, according to Brent Ruby, director of the Montana Center for Work Physiology and Exercise Metabolism, a phenomenon called exertional heat stress can also lead to heat stroke, even in pleasant weather conditions. But what exactly is exertional heat stress? Says Ruby: “Exertional heat stress causes runners to sort of back out of their ego, and let your mind tell you to slow down, get in the shade, or get water on top of you”. However, super competitive runners tend to override that urge.

So while hot and humid conditions are normally associated with heat stroke, don’t be fooled. You may just fall prey to it in cooler conditions too.

Tips for preventing heat stroke as a runner

Fortunately, there is plenty you can do to prevent heat stroke. Experts recommend taking the following actions to keep it at bay:

  • Don’t push too hard on hot, humid days. Especially if you’re used to running in cooler conditions.
  • Know and listen to your body. Even in pleasant weather conditions. If your brain tells you to slow down, get into the shade, drink some water or cool your body down, then do it. No PB or coach’s instructions are worth risking your health or life for.
  • Give your body time to acclimatize if traveling to a hot, humid race or area. According to Maharam it takes the body at least two weeks to properly adjust to these new conditions, so plan your trip accordingly. And if your schedule doesn’t allow an acclimatizing period, be sure to run early-morning or later in the evening, or stick to shady routes instead.
  • Always hydrate according to thirst. While water is fine for runs shorter than 30 minutes, an isotonic drink is recommended for anything longer than that.
  • Strategically cool your body down with water. A cup of water over the head, or sponge or spray stations can literally be a lifesaver on hot and stuffy days. Just be sure to wear quick-drying gear and lube those strategic spots before heading out!

  • Be sun smart. Always use a good quality, natural sunscreen on exposed skin and reapply every two hours. Use a cap and sunglasses to protect your eyes.
  • Dress for success. Ditch that beloved old cotton race t-shirt and opt for light-colored, loose-fitting, moisture-wicking fabrics instead. And that goes for socks and underwear too.
  • Choose your route carefully. Since asphalt and concrete tend to retain heat, best avoid these surfaces on sweltering days. Opt for natural, tree-rich areas where you can.
  • Mind your meds. Taking cold medicines, ephedrine, pseudoephedrine, diet pills, or anti-diarrhea medication, all with dehydrating qualities, before a run, could contribute to an increased risk for heat illness.
  • Go easy on the alcohol. Just like certain medications, alcohol can also have a dehydrating effect. So don’t go overboard the night before a run or race.
  • Reconsider your race plans if you’ve been sick in the week leading up to your race. Any type of illness, especially that associated with fever, in the week leading up to an event increases your susceptibility to heat stroke. So consider skipping the race or rescheduling that run instead.
  • Run on (or in) water. Swap out a normal run for a pool run on uncomfortably hot days.

Do your bit to stay safe

So while the consequences of heat stroke can be potentially fatal, it is 100% preventable. Check that ego at the door and do your bit to stay safe and healthy!


  1. Jennifer van Allen, Running in the heat, Online publication
  2. Jessie Geoffray, What runners need to know about heat stroke, Online publication
  3. Mario Fraioli, Ask the running doc: How can I train and race in the heat?, Online publication

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