To Really Beat the Heat, Head to the Sauna

Published July 19, 2023 07:41AM

If you’re looking for a way to beat the heat this summer, you might want to head to the sauna. Training and racing in hot and humid climes can be quite an intimidating prospect, so it’s understandable that athletes want to be as prepared as possible. While it’s important to actually get out and run in the heat if you’re getting ready for a balmy race, time spent in the sauna can be a great method to get the adaptations you need, especially for women.

The benefits of spending time in the sauna have been well documented over the years, with research showing it can help reduce high blood pressure, cardiovascular disease, stroke, and dementia, as well as decrease inflammation. This is largely attributed to the fact the body responds to the sauna in a similar way it does to exercise—the sweat response is triggered and heart rate and temperature rise. But better yet, sauna training—that is, deliberately spending time in the sauna after a workout—can be a very efficient way to expedite the heat acclimation process.

Heat Acclimation for Athletes

Heat acclimation is strongly recommended before a hot race, as it helps to expand blood plasma volume, increase sweating, and boost vasodilation at your skin so that your body can cool more quickly and efficiently. And as is the case with many aspects of physiology and training, it’s fast being discovered that the process is different for women compared to men, as this study from the Frontiers of Physiology highlighted.

Dr. Stacy Sims, a physiologist who has pioneered much of the female-specific training approach, has been an advocate of sauna training for some time. She said female athletes have different needs to men when it comes to training and competing in the heat, so preparing the body using a female-specific sauna protocol is key. Compared to men, women will see their core temperature rise at a lower level of dehydration because they have a lower volume of body water, she said.

While it might sound uncomfortable, sauna training is the simple act of heading to the sauna after a workout or at the end of the day, and spending 20 to 30 minutes in there. The combination of low blood volume and thermal stress help trigger a cascade of physiological processes that research has shown will help your body handle heat and humidity far more efficiently. And the good news? There’s now a growing body of evidence to suggest that women respond to it exceptionally well, especially those with higher levels of fitness. The above-referenced study from Frontiers in Physiology found that women who followed a four-day heat training protocol did not show improvements in performance during a 15-minute cycling time trial in a 95 degree F environment. However, women who followed a nine-day heat training protocol improved their mean power output by 8%, their speed by 3%, and went 3% farther during the same time trial.

“For women, sauna training can be especially helpful for performing in both heat and cold, as well as at altitude,” Dr. Sims said. “Women generally sweat less and start sweating later than men. We vasodilate first, then sweat, meaning our internal temperature that kickstarts sweating is higher than men’s.” This is explained in depth in this study in the Journal of Applied Physiology.

When you spend time in the sauna your body responds by sending blood to the skin to help you sweat. Dr. Sims said: “With limited blood volume to spare, your kidneys will sense that you need more red blood cells to get oxygen to your organs and will produce more EPO (erythropoietin) and plasma volume, which boosts your blood volume and subsequent performance.”

Women’s Specific Heat Training

Until recently, most of the research had been on men, but it is now known that a nine-day protocol for women is better than the standard four-day template that favors men. If you’re in a traditional sauna you can expect the temperature to be up to about 185 degrees F, while infrared saunas typically heat to about 140 degrees F. Dr. Sims advocates sessions that are 20 to 30 minutes in duration, but she emphasizes that you should only stay in for as long as is comfortable, and it can take time to build up to 20-30 minutes. After the session, rehydrate slowly, don’t suddenly take on a large volume of fluid.

Remember that where you are in your cycle will impact how you feel and how you adapt too. Dr. Sims said: “We have different heat-loss responses across the phases of our menstrual cycle (and a fluctuating internal temperature because of the changes in estrogen and progesterone). In the low hormone phase, which is right before, during, and right after your period, your body needs a 5 to 10-minute ‘primer’ of heat exposure before the full session. So go into the sauna and heat up. Then get out for five to 10 minutes before starting your actual session. If you’re in the high hormone phase, your body has already shifted to a higher thermoregulatory threshold, and no primer is needed.”

During the low hormone phase of your cycle, your core temperature is slightly elevated, your heat tolerance is lower, and you’ll start sweating later after starting to exercise, which means you’ll need to be particularly diligent about staying hydrated and rehydrating well.

Remember that if you’re planning to use the nine-day protocol heading into a race Dr. Sims advises completing the sauna training five to six days before the race, i.e., starting the sauna protocol at least 14 to 15 days pre-race.