Sauna benefits: get stronger and live longer
Sometimes, there is only a very slight difference between high performers and those who just spin their wheels. The latter often do most of the things high performers do, but still fail to achieve the same results. This is because high performers know about and implement little tricks that may seem unimportant at first but which, in combination, make a significant difference. Each incremental effort, each little detail can provide that slight edge and lead to greater results.
One of such tricks that can make you stronger, healthier, leaner and more resilient is quite simple, but yet –little known to most people. We are, of course, talking about hyperthermic conditioning, more commonly referred to as “sauna”.
When it comes to the goals listed above, sauna is typically not on most people’s list. Some enjoy the process – especially when it involves some social element, as well (in many cultures sauna is a place to spend time with friends and socialize), some use it for all the wrong reasons (yes, there are still many misconceptions and myths surrounding sauna use), yet some others (especially those who don’t do it right) don’t really care about it – but few people really think of sauna as some superhero-lab-level procedure and performance enhancer.
Which is unfortunate, because – with healthy individuals who have no pre-existing medical conditions that would restrict sauna use – it is a wonderful and grossly underutilized tool that can help on many different fronts.
Let’s look at what intense heat can actually do for you – and how to use it properly (heads up: sauna benefits have very little to do directly with sweating and flushing out the mythical “toxins” as a result, as many gurus would have you believe – the mechanisms involved are actually much more interesting).
Types of heat
While a lot of people feel discomfort when subjected to heat (just think about how miserable you would feel if you stayed indoors on a hot summer day without air conditioning!), there is no shortage of different types of controlled heat exposure: wet sauna, dry sauna, infrared sauna, Turkish hammam, Russian banya, Swedish Bastu – all of these serve a single purpose: to elevate your core body temperature. Although most studies sauna benefits were performed with dry saunas (given that many of these studies come from Finland, where dry saunas are more traditional), the positive effects of heat exposure have actually been associated with wet saunas, as well. Dry heat is usually easier to tolerate – and thus, in theory, can be used at higher temperature setting than moist heat, but it all comes to personal preference and the level of comfort.
For that reason, we will not differentiate between the two types of heat – it doesn’t matter which method you use to elevate your core temperature.
What good could something as uncomfortable as intense heat do for our bodies? As it turns out – there are quite a few benefits! The ones we are going to discuss today relate to:
- Athletic performance, including endurance, recovery and even muscle hypertrophy;
- Cognitive improvements;
- Hormonal response;
- Prevention of oxidative stress;
- Overall longevity
Yes, heat can do all that – and more! Let’s take a deep dive and see how we can better use heat to our advantage.
Heat Shock Proteins
Heat is a stressor – high temperatures can definitely be damaging. However, intermittent exposure to heat that is high enough to be uncomfortable, but not high enough to cause damage, triggers a hormetic response that results in all kinds of positive benefits. Hormesis, if you recall from prior articles, is a type of a protective mechanism that results in favorable biological response to low-dose stressors (or toxins), resulting in increased repair of the damage not only caused by the stressor itself, but also other low-level damage that might have accumulated previously.
One very important type of such hormetic response when it comes to heat exposure is activation of heat shock proteins. Heat Shock Proteins are a group of special proteins (which are, as the name suggests, triggered by heat) that function as intra-cellular chaperones for other proteins and play an important role in protein-protein interactions such as folding, assisting in the establishment of proper protein conformation (shape) and prevention of unwanted protein aggregation.
Here are some benefits of activating heat shock proteins:
- HSPs can repair unfolded, misfolded or otherwise damaged proteins thereby ensuring those proteins maintain proper structure and function. Unfolded or partially folded proteins are unstable, tend to aggregate and precipitate and thus interfere with normal cellular functions.
- HSPs prevent oxidative damage by directly scavenging free radicals and supporting recycling of glutathione (your body’s master anti-oxidant). This prevents degradation of other proteins typically associated with free radicals.
- What this means is that HSPs are important in cellular repairs (including repair to damaged DNA). Given that HSPs may perform their function in many types of cells, this may present a very wide range of benefits ranging from improvement in eye diseases, to alleviating cardiovascular problems, to fixing gastrointestinal issues, to helping in neurodegenerative disorders, such as Parkinson’s or Alzheimer’s.
- Potentially due to the reasons above – or through other mechanisms – some studies associate sauna use with a significant decrease in all-cause mortality. In other words – heat acclimation can potentially make you live longer!
One interesting thing about heat shock proteins is that acclimation not only causes a higher basal expression of HSPs at the time of the exposure, but also results in a more robust expression upon future heat stress, leading to thermotolerance – or lower cellular heat stress in acclimated individuals with subsequent exposures. Further in this article you will see how this can also potentially improve your exercise performance, but for now just remember that positive effects of hyperthermic conditioning do not just end immediately following the exposure. As with many stressors (and heat, no doubt, is one of them), your body actually tries to adapt and overcompensate – to protect itself from subsequent exposures. Your cardiovascular and thermoregulatory mechanisms improve and the negative effects associated with elevations in body temperature get reduced.
Effect of sauna use on endocrine and other systems
Sauna benefits under controlled heat exposure do not stop with HSPs. Heat also appears to have significant impact on many important hormones.
First, sauna has massive effect on human growth hormone (HGH), increasing it 2 to 5 times during sauna bathing (although the levels return to normal shortly after heat exposure – we will cover the significance of this later in this article).
Sauna also triggers a significant decrease in fasting blood glucose and improved insulin sensitivity, which may have a profound effect in people who are trying to lose weight. You probably have seen those dorky sauna suits that just make you sweat and, supposedly “melt” the body fat? Well, unfortunately, sauna suits don’t work (for the reasons we are not going to get into too much – suffice it to say that you need a somewhat prolonged exposure at high enough temperatures) – but regular sauna very well might.
Some other sauna benefits and adaptations triggered by regular use:
- Improved cardiovascular function, lower heart rate for a given load and higher heart rate variability (it’s a good thing!);
- Higher sweat rate and sweat sensitivity as a function of increased thermoregulatory control – what that means is that your body learns to cool itself down more efficiently, and next time you are exposed to heat you can withstand it better. After acclimation, sweating occurs at a lower core temperature and the sweat rate is maintained for a longer period (you probably experienced this profuse sweating long after a steamy shower or sauna).
- Increased muscle and peripheral tissue perfusion (blood flow), resulting in better nutrient delivery (great for post-injury muscle recovery) and – because of such improved perfusion – reduced rate of glycogen depletion. Why is this important? Because lower rate of glycogen depletion means your muscle can work longer (and, often – stronger), which has great significance for athletes.
- Increased plasma, red blood cell count and total blood volume
- Increased efficiency of oxygen transport
What does it mean for athletes?
Exercise normally causes elevation in body temperature and prior acclimation to heat gets you better prepared for it. Recall that increase in body temperature is often causing a sharp decrease in physical performance, including strength and endurance – to a point where cooling the body down during exercise results in significant improvements in results. So, naturally, if the effect of raising core temperature during exercise can be better mediated by your body, you will get performance enhancement. Regular heat acclimation, therefore, becomes a mechanism of triggering such performance enhancement.
A lot of sauna benefits described above have increased significance for athletes. For instance, heat acclimation induces adaptations that improve exercise tolerance in hot conditions. Specifically, acclimation to heat reduces resting heart rate and improves cardiovascular function in general, reduces core body temperature during subsequent workouts, increases blood flow to skeletal muscle and other tissues, increased red blood cell count and improved efficiency of oxygen transport to muscles. Essentially, what this means is that once you acclimate to heat, your body gets better prepared for your next intense exercise.
But it’s not just about better efficiency in dissipating heat. Some studies demonstrated that muscle glycogen use after heat acclimation was half of glycogen use before heat acclimation. This has great significance for endurance athletes who can, metaphorically speaking, go longer using the same fuel tank. In one study, a 30-minute sauna session two times a week for three weeks post-workout increased the time that it took for study participants to run until exhaustion by 32%. In addition, heat acclimation reduces lactate accumulation in blood and muscle during exercise.
Not an endurance athlete and concerned more about muscle hypertrophy? Sauna can definitely help you, too! After all, heat shock proteins trigger synthesis of other proteins and, even more importantly, reduce the rate of protein degradation – and this net positive effect is what is important for muscle hypertrophy.
Heat leads to improvement in insulin sensitivity in muscle tissue (by increasing the expression of GLUT4 glucose transporter). When your muscles are more sensitive to the effect of insulin, its metabolic effect on skeletal muscle becomes more pronounced. Insulin is an anabolic hormone because it increases protein synthesis (by stimulating the uptake of amino acids – particularly BCAAs – into skeletal muscle and because it decreases protein degradation through inhibition of a protein complex inside cells responsible for the degradation of most cellular proteins – both of these actions, once again, lead to net protein synthesis. In fact, insulin deficiency and insulin resistance (such as in Type 1 or 2 diabetes) are associated with increased skeletal muscle breakdown.
Finally, heat triggers significant release of growth hormone (which initiates several anabolic processes, such as synthesis of IGF-1, activation of mTOR pathway, etc.) and becomes a direct trigger of muscle growth – so, in the end, supplementing your exercise with sauna use becomes a no-brainer. Although you would probably get at least some benefits at any temperature, as long as it is subjectively hot, the interesting thing demonstrated by studies is that higher sauna temperatures actually trigger higher release of growth hormone. One study demonstrated that by changing the temperature of a dry sauna from 80°C (176°F) to 100°C (212°F) (even when total time was reduced from 20 to 15 minutes for each of the two sessions) resulted in an increase in growth hormone from twofold at 80°C to fivefold at 100°C over baseline – and this effect actually increases .
Sauna and exercise recovery
As a natural byproduct of their function, our cells produce reactive oxygen species (also often called “free radicals”). During exercise – when your mitochondria has to meet higher demand for energy generation – the number of reactive oxygen species, such as superoxide and hydrogen peroxide, naturally increases, causing oxidative stress.
Unfortunately, oxidative stress is a major source of protein degradation. But if you prevent protein degradation, while keeping post-exercise protein synthesis constant, you create anabolic conditions necessary for muscle hypertrophy.
Because of improved blood perfusion, nutrient delivery and removal of metabolic byproducts speeds up – which naturally improves muscle synthesis.
In extreme cases, when exercise sessions become very intense, it may get to a point when myoglobin, released into the bloodstream at the time of muscle tissue breakdown, accumulates to toxic and dangerous levels that can cause kidney failure. Most people who are sensible about their exercise schedule and intensity do not get to this, but it’s comforting to know that, once again, mediating effects of heat shock proteins (which – if you had prior heat conditioning – are expressed at higher levels during exercise-triggered elevations in core body temperature) can protect your kidneys from these toxic byproducts.
Can sauna make you live longer?
One Finnish study found that sauna bathing 2-3 times a week was associated with a 24% decrease in the risk of all-cause mortality. Although there are not very many human studies on the subject, those done on insects indicate that expression of heat shock proteins (even those that are not directly responsible for protein refolding) prevents toxic protein aggregation and leads to an increase in lifespan.
Before you brush off the results of studies done on mice or insects as irrelevant to humans – keep in mind that a lot of valid conclusions can be – and have been – made based on such studies. This is understandable, given the strikingly high number of genes we share with different species. This number is as high as 98% when it comes to mice and about 44% when it comes to fruit flies.
Coming back to aging – the role of HSPs in delaying aging makes sense if you recall that “aging” is, essentially, just a physical manifestation of cellular senescence, accumulated irreparable damage and loss of normal function – often because of malfolded proteins. If you repair the damage quicker (or avoid it in the first place) you should be able to significantly postpone aging as we know it.
Studies demonstrate that hyperthermic conditioning increases the release of norepinephrine 2-to 4- fold, and prolactin –10-fold. Norepinephrine mobilizes the brain and body for action (it plays a part in the “fight-or-flight” response), but in the brain specifically – norepinephrine increases arousal and alertness, promotes vigilance, enhances formation and retrieval of memory, and promotes focus and attention.
Although prolactin is best known for its role in enabling lactation in females following pregnancy, it is actually has a wide range of other functions. It regulates behavioral function, the immune system, metabolism, reproductive systems and many different bodily fluids and is crucial hormone for overall health and well-being, for both men and women. Specifically as it relates to the improvement in cognitive function, prolactin stimulates production of oligodendrocytes – the cells responsible for the formation of myelin coatings (the “white matter”) on axons in the central nervous system. Myelin sheath serves as an insulator for the nerves – its main purpose is to increase the speed at which impulses propagate along the myelinated fibers. As such, myelin is vital for learning new skills.
In addition, heat stress, when used in conjunction with exercise has been shown to increase the expression of brain-derived neurotrophic factor (BDNF). BDNF levels are positively correlated with attention, improvements in memory and non-memory cognitive domains. BDNF also increases the growth of new brain cells as well as the survival of existing neurons and even fights anxiety and depression.
Finally, as another contributor to delaying aging, frequent sauna use reduces the risk of dementia.
When to avoid sauna
Of course, it goes without saying that extreme heat exposure is not for everyone. Pregnant women and people with existing cardiovascular issues, blood pressure problems or any serious medical condition should generally avoid extreme sauna use (although many studies actually conclude that even for patients with existing cardiovascular problems, there are no detrimental effects from moderate sauna use – on the contrary, such studies note certain improvements in cardiovascular function. But, generally speaking, if you have any medical condition – pre-clear sauna use with your doctor. And, most importantly, if you are just starting out, don’t go for extremes – start slow, with 10-minute-long sessions at moderately high temperatures and then, with time, gradually increase the time spent in the sauna and move on to higher heat. Even then, sauna should not be totally intolerable – moderate level of discomfort for a relatively short period of time is fine and even expected, but don’t stay in extreme heat longer than your body can take – this is especially true if you are recovering from other stress (exhaustive exercise, adrenal fatigue, etc.). In other words, don’t aim for hour-long daily sauna sessions – it is not necessary and the diminishing returns may actually turn into a health hazard at some point. 20-30 minute sessions for well-acclimated individuals seem to work quite well.
Remember that sauna use does not mix well with alcohol (it can actually be very dangerous) – alcohol consumption during sauna bathing increases the risk of hypotension, arrhythmia, and sudden death. Because you will be using a lot of liquids (and electrolytes) with sweat – replenish them after your sauna session with water that has a good mineral content (or just make sure you get your increased dose of minerals through supplements and food.