Sweltering Sauna or Cold Plunge? Getting Comfortable with Being Uncomfortable Can Boost Performance and Health. UPDATED

cold heat May 23, 2023

The science behind ice baths and sauna sessions.

Extreme temperature treatments have been a hot (pun intended) trend for the past few years. Long time athlete Gabby Reece famously swears by super hot (up to 220 degrees F!) sauna treatments followed by icy cold plunges and Lady Gaga’s Instagram feed is peppered with her submerged in ice as part of her post-show routine that includes alternating between cold and hot treatments.

I’m not one to follow influencers, but both these women are correct that getting comfortable with getting uncomfortable in both hot and cold conditions can be good for your performance and your health—with women reaping some specific benefits.

The Science Behind Sauna

Cultures around the world have used saunas for health benefits for thousands of years, with good reason: a 2018 research round up reported that sauna use was linked to a reduction in high blood pressure, cardiovascular disease, and stroke, as well as pulmonary disease and neurocognitive diseases like dementia. It also appears to alleviate pain associated with inflammation and arthritis. Other research finds it reduces the risk of early death.

That’s likely because your body responds to sauna the same way it does to moderate- to high-intensity exercise: your heart rate goes up by about 30 percent, your body temperature rises, you break a sweat, and your body produces hormones like noradrenaline and growth hormone. So, you get health benefits similar to a good workout. The benefits are even better for people who exercise regularly. The study found that having high fitness levels from regular exercise plus regular sauna treatments provide extra cardiovascular benefits.

For women, sauna training can be especially helpful for performing in both heat and cold, as well as at altitude. Women generally sweat less and start sweating later than men. We vasodilate first, then sweat, meaning our internal temperature that kick-starts sweating is higher than men’s. We also 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 luteal phase of your cycle, especially when hormones are highest in the week or so before your period, your core temp is slightly elevated; you start sweating later after starting exercise, and your blood plasma volume is reduced by up to 8 percent. That means your tolerance for heat is lower.

With the onset of menopause, heat-loss responses are significantly inhibited, and although they can be improved with increased endurance fitness, it can still be an issue for performance.

Sauna treatments can help improve heat tolerance and performance. Research shows that the dehydration that comes from training or at the end of the day can help reduce the time needed in the sauna to get adaptations. When you head into the sauna at those times, your body will respond as expected by sending blood to your skin to help you sweat and avoid overheating. 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.

Sauna treatments (especially post-exercise) also reset your thermoregulation thresholds, so hot temps feel less overwhelming, and improve your performance at high altitude, where the mountain air is dry and dehydrating. Research also finds that heat acclimation improves performance in temperate and cool conditions as well.

Traditional saunas heat up the surrounding air to up to about 185 degrees F (85C), while infrared saunas heat to approximately 140 degrees F (60C). The general guideline is for 25 to 30-minute sessions where the temperature doesn’t exceed 165 degrees F (I don’t recommend going into the super high territory that Reece does unless you’re very experienced with sauna treatments). You also should only stay in for as long as you feel comfortable.

Short-term heat acclimation protocols are often used to prepare for competition in the heat because they are cost and time-efficient. For women, we now know that a 9 day protocol improves cardiovascular and thermoregulatory adaptations similar to the 4 or 5-day protocol in men. But if a woman needs to accelerate her heat adaptation and follow the shorter 4 to 5-day protocol, using a primer first, before the true sauna session, can help push those adaptation responses along a bit quicker. 

For more heat acclimation strategies, check out my blog on how to Beat the Heat.

The Science Behind Cold Plunges

Most of us are familiar with ice baths for recovery after intense workouts like marathons and heavy strength sessions. Initially, the thought was if cold was used, constriction would occur, reducing inflammation and thus pain. And yes, this does happen, but in times when we want to invoke inflammation for adaptation, cold exposure can be a hindrance to recovery and slow adaptations.   

There are also sex differences. Cooling your body works by tricking your body into redistributing the blood from the skin back into circulation through the muscles. Men don’t necessarily need this, because their blood vessels naturally constrict postexercise to push blood away from the skin and back into the central circulation. Women on the other hand tend to vasodilate after exercise, meaning our blood tends to pool in our skin, dropping blood pressure and reducing blood flow to the damaged muscle. Cold water immersion for women can help speed up vasoconstriction after hard exertion, to get blood back centrally helping to increase blood pressure and circulation into the muscles. 

Like sauna, there’s also a long history of using cold water immersion for general health benefits. Wim Hof has popularized it in the modern mainstream as a way to reduce inflammation, improve hormonal and metabolic health, increase fat-burning metabolism by building up more metabolically active brown fat, and boost endorphins to elevate mood (research shows that cold plunges can help relieve depressive symptoms). The long-term effects are similar to exercise with a decrease in heart rate and better vascular control.

There are some sex differences here as well. The body’s response to cold-water immersion is to release norepinephrine, which can help decrease inflammation and can help increase your energy levels and mental focus. There are anecdotal reports and some evidence that cold exposure also improves immunity. However, research shows that despite the similar experience of cold strain in men and women, the neuroendocrine and immune responses were larger in men. (That’s not to say women don’t benefit at all in this regard.)

For women in the menopause transition who need help with thermoregulation, especially around sleep, I recommend taking a cool shower before bedtime to help bring down the core temperature and lull you to sleep. Start with the water on warm (so you don’t shock your system) and gradually turn the hot water down until the temperature is cool and you feel chilled. Then get in your PJs, curl up in your sheets, and feel the pleasant tiredness wash over you.

If you’re interested in incorporating cold plunges into your regular routine, remember that women do not need as cold a plunge as men. Women start shivering at a higher temperature than men, are more sensitive to cold exposure, and feel colder and less comfortable than men during the same cooling protocol. The research into specific protocols is still sparse, but in general, cold water immersion is exposure up to the shoulders or neck to water between 32 and 59 degrees F (0 to 15 degrees C). Immersion times range from 2 x 30 seconds with 2 minutes between at the lowest temperatures; to 6 x 3 minutes at 59 degrees F/15 degrees C. 

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