Long, clear summer days are ideal for running. You can pack in a long adventure on the weekend or easily fit in a pre-or post-work run in the daylight. As nice as the summer days are, the heat can really take it out of you. Maybe you’ve noticed you have to work a little harder on each run. Maybe you just feel a bit sluggish. Maybe you were hitting PRs this spring and can’t quite find that speed anymore. That’s normal, and here’s why.

When you go for a run, blood is pumped from your heart to your muscles to provide them with oxygen and nutrients. Additionally, some blood goes to the skin to help with cooling as the body generates a lot of heat when running. As temperature increases, more and more blood goes to the skin to aid with cooling. While this is essential to prevent overheating, it means there is less blood left to carry oxygen to your muscles. With less oxygen going to your legs, it is physiologically harder to run.


Backcountry Rise 50k competitors in the summer heat (James Holk)


There are two methods to combat the heat: heat training and heat management. Heat training causes physiological adaptations that will better prepare the body for heat. Heat management aids the body in cooling.

Heat training will be helpful for any race in hot weather. Sauna training is the most common form of heat training and has the most research on its effectiveness. Sauna temperatures typically range from 160° to 180°F, which is substantially hotter than outdoor temperatures. This increased temperature forces the body to adapt to the added heat stress. Sauna training will expand blood plasma volume, reduce the core temperature during exercise in the heat, and reduce heart rate during exercise in the heat. All of these adaptations will improve your running performance in the heat! These adaptations occur relatively quickly, so the best way to add sauna training into your race preparation is to do 3-4 sauna sessions per week for 3-4 weeks before a race. A sauna session can last anywhere from 15 minutes to 1 hour. When you begin sauna training, start with 10-15 minutes and slowly build up to longer durations as your body increases its heat tolerance. Make sure to bring water with you in the sauna to stay hydrated. Hydrating after your sauna session is equally important, as you will lose a lot of sweat while in the sauna. Sauna training is surprisingly taxing, so make sure you give your body a chance to recover from this added training stress.


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Heat management helps your body stay cool in the heat. Dousing yourself with water or using an ice bandana are the two most common forms of heat management. While ice will be more effective for cooling, it is not always available. Using water from a creek or an aid station is also a good option. Dousing yourself with water aids in cooling the same way that sweat aids in cooling. Instead of being cooled by the ambient air temperature (which might not be cooling you off if it’s hot!), you are being cooled by evaporation. What does this mean? Evaporation is when water is turned from a liquid to a vapor. This phase change takes a lot of energy, and that energy has to come from somewhere. In this case, the energy comes in the form of heat generated by your body. When you are running, evaporating sweat and water pull heat from your body which in turn cools your body. This is why water (and sweat) are so effective at cooling your body. Ice is similar to water, but it starts at a lower temperature and needs to undergo two phase changes (solid to liquid, then liquid to vapor). As it takes significantly more energy to turn ice into vapor, ice will extract more heat from your body, making it more effective for cooling. However, ice is not readily available on most race courses.


A Mt. Hood 50 mile runner getting cooled off via aid station sponge bath. (Paul Nelson)


Hopefully, these techniques to stay cool will help at your next summer race! Remember, it is harder to run fast in the heat, so be easy on yourself if you are feeling a little sluggish in the heat. With that said, using a combination of heat training and heat management, you can combat the heat and run your best this summer!

Email Andrew Miller for more coaching techniques at andrewmillercoaching@gmail.com.

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