The Benefits of Heat Exposure on Health and Performance

Earlier this year we explored the world of cryotherapy and the effects it can have on overall health and physical performance. As stated in that article, exposure to extreme temperatures is far from commonplace in our modern day lives. Mostly every building in developed countries is equipped with climate control, whether it be A/C or central heat. But that doesn’t mean we can’t still adapt to extreme temperatures if need be. We now know that exposure to extreme cold has many benefits to our body. Whether the result be reduced inflammation, improved brain function and health, or improved athletic performance, it seems everyone can benefit from cold exposure therapy. This makes you think, if there are so many benefits to cold exposure, shouldn’t there some benefit to heat exposure as well? Although we might make fun of the elderly folks relaxing in the sauna at our gym, it seems that they might be on to something after all. There is quite a bit of evidence to suggest that regular exposure to hyperthermic (extreme heat) conditions has a plethora of benefits to our body as well. In fact, you’ll find that heat exposure shares some of the same benefits that are seen from cold exposure. However, they are not identical, so it is worth investigating the benefits of heat exposure a bit further.

Health Benefits of Heat Exposure

Just as with cold therapy, heat exposure has a whole host of potential benefits to overall health. So once again, let’s break it down into sections that cover each aspect of our health.

Inflammation and Pain

One of the major adaptations that occurs from heat exposure is the activation of heat shock proteins (HSP’s) which have several effects on different areas of the body. These HSP’s have been shown to increase dramatically from heat acclimation in a sauna with temperatures upwards of 140 – 180 degrees Fahrenheit. Several of these HSP’s have anti-inflammatory properties [10][18]. Specifically, HSP70 has been shown to have a robust anti-inflammatory effect and has been positively linked to increased longevity in humans (Singh). A recent study also showed that the frequency of sauna use is inversely related to C-reactive protein levels, which is a marker of systemic inflammation [9]. In other words, the more frequent the sauna use, the lower the inflammation.

HSP’s are not the only anti-inflammatory byproducts of sauna use. Just as we see in cold exposure, heat exposure to “volitional fatigue” causes over a 300% increase in norepinephrine [8]. This has several implications for inflammation as norepinephrine decreases the levels of certain inflammatory cytokines such as tumor necrosis factor alpha (TNF-α) and macrophage inflammatory protein 1 alpha (MIP-1α) [3, 4]. Adding to this evidence are studies that show a reduction in pain for rheumatoid arthritis patients who undergo frequent heat exposure via sauna [11]. These patients present with overactive inflammatory cytokines, so it seems plausible that the sauna use is reducing their pain via the increase of norepinephrine which then leads to a reduction in those inflammatory cytokines.

Brain Health

Research shows that HSP’s are protective to the brain especially during times of ischemia, such as during a stroke or traumatic brain injury [17]. So one great benefit from consistent heat exposure would be this protective effect due to the increase in HSP’s. But beyond that, heat exposure has also been shown to increase levels of brain derived neurotrophic factor (BDNF) in the body [6]. This effect is also compounded when combined with regular exercise. BDNF is a powerful regulator of brain development and has implications with respect to improving learning, memory, and neuroplasticity. So it seems that spending time in the sauna is extremely helpful for preserving the integrity of existing brain cells as well as promoting the development of new neural tissue.

Going back to the hormone norepinephrine, we see additional benefits beyond just inflammation reduction. This hormone acts to help the brain promote attention and focus. This is important for people who want to make the most of their productivity at work or in school. However, norepinephrine also acts as a mood modulator by promoting happiness. For this reason, regular sauna use could be a helpful tool for those who suffer from occasional depression or anxiety [13]. Although it may not be enough to replace traditional therapies, certainly adding some sauna use should lend a helping hand in regulating your mood.

Detoxification

The word “detox” has become somewhat of a hot button word in the world of health and fitness lately. Certainly there are a lot of scam products and services out there which claim amazing detox benefits. And yes, our liver is our master detoxifier and does a very good job of doing so. However, with the constant onslaught of toxic environments in our modern world, even our liver can get a bit overwhelmed at times. When these toxins and toxicants cannot be efficiently removed from the body, they get stored in our fat cells and other organ tissues [1][5]. So giving the liver a helping hand is not a bad thing when it comes to dealing with our toxic environment.

Thankfully, one of the most robust forms of detoxification is sweating. Of course, we all sweat when engaging in exercise, but not to the same degree that is achieved through prolonged heat exposure. Through sauna use specifically, perfusion of adipose, liver, and kidneys increases the amount of metabolic activity in those organs. This leads to increased removal of toxic substances via circulation to the skin which is then excreted via sweat during heat exposure [2]. Overall, this decreases the burden on your liver, kidneys, and other organs in terms of toxic load. So whether you believe in detox or not, the science is clear on the pathways of physiology with respect to sauna use and their implications for detoxification and health.

Performance Benefits of Heat Exposure

Now the health benefits of heat exposure are all well and good, but I’m sure you’d like to know how jumping in the sauna can help you get in shape, right? Well thankfully there is good research to suggest that heat exposure has some major performance benefits as well.

Aerobic System

If you are one of those people who believes in conditioning as a part of overall fitness (like myself), you will be happy to know that sauna use can help. Through the activation of heat shock proteins and their effect on inflammation, mitochondrial health is improved substantially. Healthy mitochondria enable us to make more ATP per unit of time. This has huge implications for aerobic exercise with respect to delivering energy to the exercising muscle. Not only will you be able to sustain a higher rate of exercise, but you’ll be able to recover from that exercise more efficiently.

On top of that obvious benefit, heat exposure has been shown to have a profound impact on the thermoregulatory and cardiovascular systems. Through heat acclimation, the body is better able to control body temperature, which helps to keep you cooler during exercise [12]. Additionally, blood volume and fluid balance are improved from heat acclimation. All these adaptations allow you to stave off any ill effects which result from dehydration or increased body temperature during exercise. Going even further, we see that cardiac stability and blood perfusion to the heart are improved, which allows the heart to work more efficiently during exercise [12]. While it is not clear whether these adaptations result in improved time trial/race performance, they do seem to improve time to exhaustion during endurance exercise [14].

Skeletal Muscle

Of course, most of you didn’t come here to read about the endurance benefits of sauna use. You want to know how heat exposure can benefit you in the weight room. Interestingly, heat exposure seems to have an even greater effect on skeletal muscle than it does on the aerobic system.

The HSP’s that are activated from heat exposure actually have a robust effect on net protein balance in the body. While they do not necessarily trigger muscle protein synthesis (MPS), they do inhibit protein breakdown [15]. This effectively shifts the balance into positive net protein balance which, when training is applied, results in enhanced muscle hypertrophy.

Additionally, heat exposure causes a huge increase in growth hormone (GH) release and may improve insulin sensitivity [7][8]. While GH may not be anabolic per se, it does offer some nice anti-catabolic effects as well as connective tissue benefits. However, GH also stimulates the release of insulin like growth factor 1. IGF-1 can then activate the mTOR pathway leading to MPS as well as activate FOXO, which further inhibits protein degradation.

Looking at the effect of improved insulin sensitivity, we also see benefits in these same areas. Insulin stimulates MPS directly after a meal and also inhibits protein breakdown. Being more sensitive to insulin allows our body to perform these tasks more efficiently.

Over time, these robust benefits to MPS and inhibition of protein breakdown will definitely lead to greater muscular adaptations. Heat exposure may also serve as a useful tool in dieting individuals who are more prone to experiencing muscle breakdown.

Conclusion

Just as we saw from cold exposure therapy, heat exposure offers a wide range of benefits to our bodies. The health benefits alone are enough to make you take notice, but even if you are purely motivated by performance enhancement, heat exposure is sure to improve your efforts in the gym. Although you may have to brave some uncomfortable moments with some naked (but unashamed) older sauna bathers, it’s probably worth the effort. Of course, you want to make sure you stay hydrated and replace the electrolytes you lose in your sweat before and after sauna use. But responsible use of a sauna could give you the edge in your fitness journey.

References

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