Beat the Heat

Last week much of Montana had cooler, rainy weather with highs in the mid-60’s. As we turned the corner into July, the temperatures soared into the 90’s. If you went on a run this week, you probably struggled to maintain your normal pace.  Most likely you aren’t acclimatized to the heat yet – unless of course you’ve been running in a sauna.

Exercise generates excess heat which will increase our body temperature. If our body temperature gets too high, then we can risk a heat related illness such as heat exhaustion or stroke. In order to combat the rise in body temperature, our body shunts blood away from working muscle to the skin to help dissipate heat. Add the evaporation of sweat to the mix and our body becomes pretty good at keeping itself cool and safe.  Consequently, our usual effort will feel harder because of less blood and therefore oxygen is making its way to the working muscle.

However, during vigorous exercise in hot weather, the body will shunt the blood away from the skin where it is dissipating heat back to the working muscles to keep up with the oxygen demands of exercise. This can become a dangerous situation where the body’s ability to dissipate heat is compromised and core temperature can increase to dangerous levels.

To improve the body’s ability tolerate heat, acclimatization occurs with routine exposure. Adaptations such as sweating sooner and at a lower body temperature occur to help keep the body cool. This allows the body to get away with sending less blood to the skin for cooling which conveniently allows more oxygen to get to the working muscles. Also, your body builds plasma volume which increases the amount fluid in your system. So not only will heat acclimation keep you cooler and safe, but it will also improve your exercise performance in the heat.

How should I acclimatize?

Since intensity is one of the biggest drivers in skyrocketing core body temperature, your first few runs in the heat should be at a low or moderate intensity. Expect your runs to be at a slower pace than they normally are at a cooler temperature. If you have hard workout days, plan to do those in the mornings when it is still cool. After a few days of running in the heat you should start to feel like your runs are getting easier.  Eventually shift your harder runs toward the hotter part of the days, especially if you plan on racing in hot weather. Typically it takes 14 days to fully acclimatize and your body will be better prepped for racing and keeping you safe in the heat.

Couple things to monitor:

  • Body Weight: You will lose a lot of sweat when running in the heat. Try to replenish your lost body weight after a run with fluids to stay hydrated. For every pound lost, try to drink ½ a liter to rehydrate.
  • Pee Clear: Urine color is a good indication of hydration. If you are dehydrated your urine will be dark yellow. If you are hydrated you pee should be pale yellow to almost clear.
  • Running Pace: your running pace should feel easier as you acclimatize. However, you probably still won’t be able to maintain your normal race paces at 50 degrees when it is 95 degrees – acclimatized or not! Use this nifty pace calculator legendary running coach Jack Daniels  developed that adjusts your race pace according to temperature:
  • Speaking of Jack Daniels: avoid excessive alcohol during the hotter months during training because of its diuretic/dehydration effects.
  • Take Breaks: Don’t be afraid to take breaks if you are feeling super-hot. Take a couple short breaks during your run to help prevent your core temperature from getting too high!
  • Drink Cold Beverages: research has shown drinking cold beverages  during and before exercise can lower and help keep exercising core body temperature lower than if you drink tepid beverages.


Do you have strategies that you use for summer time running? Post below!

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