Some like it hot, some like it not. Whether you are a lover of saunas, or absolutely can’t stand the heat, you should know that saunas are extremely beneficial. With the use of a sauna you can enhance your athletic performance, improve your health, and boost your overall wellbeing.
Saunas are a way to hyperthermically condition your body. You may have heard that before, but may be wondering what exactly does that mean. To hyperthermically condition your body means you are basically making your body stronger through heat stress, and yes saunas are great for inducing heat stress.
Hyperthermic conditioning or heat stress can actually change your gene expression. Using this conditioning creates physiological adaptations for both highly trained and untrained athletes. So whether you are an elite athlete or just the guy down the street, saunas can improve your performance…and just you in general.
So how does this sauna and enhanced performance thing work?
To put it simply here’s the equation:
Hot Sauna + You = Stress = Adaptation = Enhanced Performance in following three areas:
- Endurance Enhancement
- Maintaining and Building Muscle Mass
- Positive Effects on the Brain
Let’s take a look at these three performance enhancements a little more in depth.
Sitting in a sauna makes you hot, you know this, but what you may not know is that it causes heat stress conditioning. So after simmering in the sauna, when you are exercising at a later time, you will experience increased blood flow to your muscles, which increases nutrient uptake in those muscles. This means that more glucose, esterified fatty acids, and oxygen will be taken into your muscles during exercise. Therefore, you will depend less on local glycogen stores (up to 50% less) and more metabolic process by-products (i.e. lactic acid) will be removed.
In looking at those that participated in a 30 minute sauna session, twice a week for 6 weeks after their running session, they found that their distance until exhaustion increased by 32% and that corresponded with a 7% increase in plasma volume and a 3.5% increase in red blood cell count, which increased oxygen delivery to their muscles.
What does all this mean for you? Basically, you won’t crash, or hit that all too familiar “wall” most every athlete has experienced, as soon as you would have before becoming heat stressed conditioned. So you can train harder and go further! Bring on the ultra-marathons!
Hyperthermic conditioning also increases blood flow to the heart. That shouldn’t be a surprise since it’s a muscle too. So of course this will increase your cardiovascular performance, enhancing your endurance. Exposing yourself to heat stress will lower your heart rate and reduce the strain on your cardiovascular system. So after sauna sessions, you can execute the same workload but your heart rate won’t’ jump up as high. This equals your ability to exercise longer.
Another nice thing that results from proper sauna use is the improvement of thermoregulatory control. That sounds pretty fancy, but all it means is that through heat acclimation (hyperthermic conditioning) you start sweating at a lower core body temperature and maintain sweat for a longer period of time. When your body has the ability to do this, it can more efficiently cool you down. Heat stress activates your sympathetic nervous system in order to increase blood flow to the skin, which increases the amount you sweat and results in cooling your core body temperature. So you can exercise longer or in hotter conditions without the crash coming on as soon.
Maintaining and Building Muscle Mass
We all know exercise results in muscular hypertrophy (the growth and increase of muscle cell size, not number), which in turn increases strength. What you may not know is that heat stress also causes us to build muscle mass. Because our muscles are constantly walking the high wire between making protein and breaking it down we have to look at both to know what our net protein production is. This is where Heat Shock Proteins (HSP) and hormesis come into action.
While exercise builds our muscles, it also puts a demand on the mitochondria in those muscles. When this happens the mitochondria use up more oxygen to make more ATP in a process called oxidative phosphorylation. This creates oxidative stress, exposing us to free radicals. While that sounds a bit bleak, have no fear, HSP is here.
These little superheroes called HSP repair damaged proteins and also prevent oxidative stress by scavenging free radicals and increasing glutathione recycling, and therefore prevent protein degradation (atrophy). So going back to the idea of net protein production, with HSP preventing degradation this equals a net increase in protein synthesis and muscle mass is maintained and subsequently built.
So you now understand the balance of hypertrophy and atrophy when it comes to exercise and HSP, but then how does heat exposures build muscle mass? Well, exposure to heat causes our bodies to increase the expressions of genes that make HSP in order to deal with the stress of the heat. This is called hormesis or a hermetic response. This hermetic response is produced through intermittent exposure to a stressor (i.e. heat from a sauna), creating a protective stress response so our bodies can adapt. With experiencing hormesis, you now, under normal conditions (no heat), will have more HSP expression and then when you are heat stressed (such as through exercise) you have even higher levels of HSP. Boom just created a stronger you!
Now HSP is not the only way hyperthermic conditioning boosts your muscle mass. Saunas (heat stress) increase the release of Growth Hormone (GH) by quite a bit. In fact, a 2x increase in GH can result from just two, back-to-back, 20-minute sauna sessions at 176°F. Now if you are one of those that takes things to the extreme, and I do mean extreme…so be cautious here, you can increase GH levels 16-fold over baseline through two 1 hour sessions with a 30-minute cooling session in between sauna sessions. This again would have to be at 176°F and completed for 3 consecutive days. Now that’s some serious sauna time.
So if you can take the heat, why is it important if saunas boost GH release? Well, GH has a nice little knack of maintaining our muscle mass because it is mediated by IGF-1 which affects protein synthesis by increasing it through the activation of mTOR* pathway and decreasing protein degradation by activating the FOXO** pathway.
Saunas boost muscle growth via HSP and GH, but wait, there’s more! Saunas also improve insulin sensitivity. Sure we have all been introduced to the hormone insulin and its sensitivity (or lack of) through the ever increasing diabetes epidemic sweeping the nation, but did you know that insulin not only works towards glucose homeostasis (by promoting the uptake of glucose into muscle and adipose tissue), but it also has a role in protein metabolism?
When your skeletal muscles are insulin sensitive the muscle cells take up glucose and this can affect protein synthesis by activating the Akt pathway. This activation increases protein synthesis by way of mTOR and decreases degradation through the FOXO pathway, but to a lesser degree than GH and IGF-1. Net protein synthesis is accomplished through the increased uptake of amino acids in muscle cells and the decrease in protein degradation through the inhibition of the proteasome (protein complex inside cells that’s responsible for the degradation of most cellular proteins). This process is why many with Type 1 diabetes can have severe muscle wasting.
Studies subjecting obese mice to intermittent heat stress have shown to reduce insulin resistance by 31%. In this study, the expression of glucose transporters in skeletal muscles, specifically GLUT4, was increased. Even though the mice were insulin resistant they could take more glucose into their muscles and signal their bodies to stop making insulin. This is where the 31% decrease comes in.
Positive Effects on the Brain
The are many ways the brain can sustain injury. This can include traumatic brain injury, ischemic injury (such as stroke), and excitotoxicity (such as with epilepsy). The brain can react to this cellular level injury through increased HSP production. However, while hyperthermic conditioning can decrease seizure frequency and help mitigate the damage they cause, hyperthermic conditioning can increase the damage caused by seizures if they occur during the heat stress period. So be careful when using a sauna!
Even with that warning, it doesn’t mean you need to fear the sauna. In fact, saunas have many positive effects on our gray matter. Heat stress increases the release and storage of norepinephrine and helps with focus and attention. Squirrel! See, if you had been using the sauna you wouldn’t have looked for the squirrel. Ok back to saunas.
The use of a sauna also increases the production of prolactin (especially in women). Prolactin is great for myelination, which makes your brain function faster and is critical for repairing nerve cell damage.
A study looking at men showed that those that stayed in the sauna (set at 176°F) until experiencing subjective exhaustion, increased norepinephrine by 310% and had a 10x increase in prolactin, plus it very slight decrease in cortisol. A separate study looking at women that stayed in a dry sauna for 20 minutes, twice a week, had an 86% increase in norepinephrine and a 510% increase in prolactin after the session. Now those are some serious numbers!
Saunas and heat stress also increase the expression of Brain Derived Neurotrophic Factor (BDNF). BDNF is important to enhance learning, memory, and neurogenesis (brain cell creation). Plus BDNF can help improve anxiety and depression induced by early-life stressful events. That’s pretty important stuff.
Getting high from getting low are also effects of time spent in the sauna. To explain what that means we have to understand dynorphins. A dynorphin is a neuropeptide which activates kappa opioid receptors (KOR), which are responsible for dysphoria, yes the opposite of euphoria. Well, that sounds depressing, doesn’t it? However, there is a bright side here.
KOR signaling during acute stress can increase physical ability (by producing the inability to feel pain) and motivation to escape a threat. However, prolonged KOR signaling in response to a chronic stress can lead to the persistent expression of depressive disorders. So why then is it good to increase dynorphin and therefore activate KOR? Well, if you can feel the low and the discomfort during your sauna session you will be ever more sensitive to the high of the later release of endorphins. Sorta like getting that kickass accomplishment feeling that washes over you after you put in the extremely hard effort. Much like the idea of no pain, no gain.
So to recap how saunas equal enhanced performance and an overall enhanced you, here are the CliffNotes.
- Enhance Endurance by:
- Increasing blood flow to the muscle
- Increasing blood flow to the heart
- Improving thermoregulatory control
- Maintain and Build Muscle Mass by:
- Boosting expression of genes that make HSP
- Boosting release of GH
- Improving Insulin Sensitivity
- Create Positive Effects on the Brain by:
- Increasing the release and storage of norepinephrine
- Increasing the production of prolactin
- Increasing the expression of Brain Derived Neurotrophic Factor (BDNF)
- Boosting the release of dynorphin and therefore activating KOR
Warning: Don’t be stupid. While yes, this a good rule of thumb to follow in anything you do, I am specifically referring to sauna use here. Excessive heat and dehydration kills people. Know your limits, listen to your body, and take care of yourself. If you have any condition that may be worsened by induced heat, then stay out of the sauna! Don’t be that idiot that cooks themselves.
Ok, that’s it. There it is, all the reasons you NEED to be in the sauna. So locate your nearest sauna, get your heat on and create a better, enhanced YOU! Happy sweating!
In case you didn’t know or just want to know more:
*mTOR: the mechanistic target of rapamycin (formally known as mammalian target of rapamycin) “is a highly conserved serine/threonine kinase that controls cell growth and metabolism in response to nutrients, growth factors, cellular energy, and stress. TOR, which was originally discovered in yeast, is conserved in all eukaryotes including plants, worms, flies, and mammals. TOR plays a key role in development and aging and has been implicated in disorders such as cancer, cardiovascular disease, obesity, and diabetes.” (Hall) For more information on mTOR transcription factors click here and here.
**FOXO Proteins: “a subgroup of the Forkhead family of transcription factors. This family is characterized by a conserved DNA-binding domain (the ‘Forkhead box’, or FOX) and comprises more than 100 members in humans, classified from FOXA to FOXR on the basis of sequence similarity. These proteins participate in very diverse functions: for example, FOXE3 is necessary for proper eye development, while FOXP2 plays a role in language acquisition. Members of class ‘O’ share the characteristic of being regulated by the insulin/PI3K/Akt signaling pathway.” (Carter, et al,) For more information on FOXO transcription factors click here.
Betz, C., et al. November 25, 2013. The Rockefeller University Press. The Journal of Cell Biology. Where is mTOR and what is it doing there? V: 203 (4). Page 563. DOI: 10.1083/jcb.201306041. https://jcb.rupress.org/content/203/4/563
Carter, M., et al. Department of Genetics and Neurosciences Program, Stanford University. Magazine R113. https://web.stanford.edu/group/brunet/Carter%20ME%202007.pdf
Hall, M. December, 2008. Biozentrum, University of Basel, Switzerland. Transplantation Proceedings. 40: 10. Pages:5-8. doi: 10.1016/j.transproceed. https://www.ncbi.nlm.nih.gov/pubmed/19100909
Patrick, R. April 10, 2014. The Tim Ferriss Show. Are Saunas the Next Big Performance-Enhancing “Drug”? https://tim.blog/2014/04/10/saunas-hyperthermic-conditioning-2/
Toll, A., et al. February 16, 2010. Brain Research. Dynorphin, stress, and depression. V: 1314. Pages: 56-73. doi: 10.1016/j.brainres.2009.09.074. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2819644/#R61