Exercising In The Heat

The early days of summer are sometimes the most dangerous when it comes to exercise, especially if you haven’t had a progressively warming spring.  Ideally, when we exercise or train outside, we get the opportunity to acclimate to heat. That is, slowly but surely the temperatures rise on a consistent basis giving our body some time to adjust our thermoregulatory systems to manage exercising in the heat.  If you are forced to exercise on a humid 80 degree day and you haven’t done so in a long time, odds are that you are going to struggle or, at the very least, not perform at your best.  That is because you body is being placed under a stress that it has not experienced lately.

Repeated exposure to heat or hot surroundings when exercising can actually improve exercise capacity resulting it the next exercise session (in the same heat) feeling a little less intense or stressful.  Technically heat acclimatization refers to “the collective physiologic adaptive changes that improve heat tolerance”.  The largest part of heat acclimatization occurs during the first week of heat exposure.  It usually requires 2-4 hours of daily heat exposure over the course of 7 days for the body to adapt.  And if a person plans to exercise in heat or is training for something, their original exercise session should be limited to 20 minutes of light activity.  Sessions can slowly increase in intensity and duration from there, using good common sense while listening to your body.  The 10% rule can come in handy here.

Hydration is especially important to prevent heat illness because sweating is one of the ways our body works to cool itself.  Large quantities of blood flow during exercise moves heat from the core to our extremities and skin.  Consuming adequate water is essential and I have written on recommended water intake in another blog post.  However, it is very easy to experience complications from the stress of exercising in the heat.  Heat related issues and complications occur more often in:

  • Those who are overweight or have a high body fat percentage.
  • Those who have not acclimated to the heat.
  • Those who are in poor physical condition.
  • Those who are dehydrated.

So, as the temperatures begin to rise, it’s important to take safe and logical steps to minimizing risk.

  1.  If you are able to acclimate, do so safely and progress with caution.
  2. Exercise early in the day if high temperatures are expected.
  3. Make sure to adequately hydrate.
  4. Replace electrolytes if necessary.
  5. Avoid caffeine or other diuretics.
  6. Wear proper attire.
  7. Work on safely reducing body fat to recommended levels.
  8. Exercise in climate controlled environments if necessary.
  9. Get adequate rest.


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