The body is highly capable of adaptation. It adapts always to every stimulus it recieves. This is one of the remarkeble qualities of the human body. The most striking example is weightlifting. During weightlifting you’ll damage muscle fibers due to the high demands you put on your body. The body responds by repairing the damage you made, growing the damaged tissue back. That’s not all, your body will improve the neurological control and grow even bigger muscle fibers to withstand heavier loads the next time you train. This is how it works for every part of your body, a karate kid will grow stronger shins due to kicking concrete bricks, your brain will become better in solving puzzles when you let it solve a lot of puzzles and so on
But the question is: Will the sauna increase your performance? To answer that you will need to know the byproducts of working-out/training: it increases energy consumption. This has several consequences: energy consumption produces heat and waste products, and damage to the body that needs to be repaired (not only muscles; bones, tendons, soft tissue and blood vessels are all exposed).
The body doesn’t like that, because it likes to keep it’s temperature stable, it likes to hold on to homeostasis
The production of heat due to energy consumption will increase the body’s temperature. The body doesn’t like that, because it likes to keep it’s temperature stable, it likes to hold on to homeostasis, since many processes in the body are influenced by changes in temperature. Meaning that is doesn’t like seeing it’s pH to increase or decrease, just as with its temperature, it will try to lower the temperature back to normal levels. For that is has several options: dilate the blood vessels (turning red), sweating and the signal to your brain telling you: ‘Hot!!’
An increasing body temperature will decrease the ability to perform, simply due to the amount of energy it costs to decrease the temperature. So if you are not used to the heat, a 35 degrees Celsius day will not be the day you will crush your 10k running PR.
Warmth can thus be a major factor in limiting your performance, but is it possible to train that? To do that you will need a room with a high temperature: like a sauna.
There is research on the subject, Scoon et al (3) did a study with well trained runners asking them to sit 30min in a sauna after a training 4 times per week comparing it with a control group that didn’t finish their training with visiting the sauna. After 3 weeks, the sauna group performed 32% better at a run test to exhaustion and decreased their 5k time with 1.9%. This is one of the few studies on the effect of sauna on performance, but there is a lot research looking at other health benefits of sauna visits which could increase your recovery.
After visiting the sauna you will see an increase in:
Visiting the sauna is a big stimulant for the production of GH: 7 visits of 30min doubled it (14) and GH increased 16 fold after 7 visits of 2 hours (6). Other studies (1,2,15,21 and 22) also show a significant increase in GH after visiting the sauna
Growth hormone (1,2,6,14,15,21,22,23) Growth hormone, abbreviated GH, is a hormone that facilitates growth, cell reproduction and cell regeneration . Furthermore, it stimulates the production of IGF-1 (insulin-like growth factor) in the liver. IGF-1 is a protein structure-wise looking like insulin. It has an important function in children during their growing phase, and continues to have an important role in tissue growth in adults. It is the trigger for the body to grow muscle-, bone-, nerve-, skin, lung-, kidney- and livertissue.
GH stimulates the production en reinforcement of bonetissue; production of muscle tissue; breaking down fat cells; and plays rolls in the immune system and homeostasis. A loss of GH will result in a relative increase in fat tissue, decrease of muscle tissue and often a decrease in energy and quality of life.
Visiting the sauna is a big stimulant for the production of GH: 7 visits of 30min doubled it (14) and GH increased 16 fold after 7 visits of 2 hours (6). Other studies (1,2,15,21 and 22) also show a significant increase in GH after visiting the sauna.
Heat shock proteins (17,18,19 en 27) These proteins are produced when the body temperature rises for example during training (19,27) but also during fever, infections and sauna visits (17). Heat shock proteins stimulate the renewing of cells, the demolition of old cells and limit tissue inflammation (18). Beside that they also seem to have an important role in improving thermoregulation and offer protection against stressful events like ischemia, cytokines and energy depletion (18). Half an hour of heat therapy gave an 3.6 fold increase in the concentration of heat shock proteins in mice (17).
Red (3) and White (20) blood cells. Red blood cells were present in higher numbers in a group athletes who finished their training with a sauna session(3). The research consisted of 2 groups, one group did a 30min sauna session after training and one group did nothing. Afterwards the sauna group showed significant higher red blood cell count. Red blood cells are the guys that transport the oxygen from the lungs to the muscles which makes them essential for energy production. That’s the reason a lot of cyclists expose themselves to altitude training, the altitude training stimulates the production of EPO which leads to higher red blood cells levels. Injecting EPO was also very popular.
In a study(20) looking at the effect of sauna usage on white blood cells, researchers compared well trained and inactive men. Both groups had a higher amount of white blood cells after a 15min sauna session, trained men showed the greatest increase. White blood cells are produced in your bone marrow and are important for the immune system by eating everything the body labels as ‘dangerous’.
Left ventricular ejection fraction (12,16) When the ejection fraction of the left ventricle (hart chamber) increases, the total amount of blood pumped to the organs rises. This makes it more efficient, meaning that it needs fewer heartbeats to eject the same amount of blood. During times of high demand (eg training) a increase in ejection fraction is a welcome quality bringing oxygen to the muscles more quickly.
Norepinephrine (4,25,26) and cortisol (1,14,15,20) (Nor)epinephrine also called (nor)adrenaline and cortisol, are often referred to as stress hormones. The body releases these hormones in times of stress, think of: speaking to a large audience, heavy workouts but also heat exposure. Norepinephrine is produced by the sympathetic nervous system. Stress hormones produces the feeling of alertness and focus, decreases inflammation, increases the glucose absorption in muscles and breaking down fat but also decreases the bloodflow to organs and elevates blood pressure. Besides norepinephrine there is also a elevation in cortisol concentration upon heat exposure. This stress hormone suppresses inflammation, heightens the glucose storage in the liver, but also facilitates the withdrawal and demolition of certain proteins inside the muscles.
Side notes: elevated concentration in norepinephrine and cortisol can have negative effects on the long run: decreased blood flow in the organs and bone density, restlessness and anxiety. A little bit of stress is good, but long-term high levels of stress will get you in trouble.
After visiting the sauna you will see a decrease in:
Blood pressure Blood pressure will decrease (13,16) due to, amongst others, brain natriuretic peptide and heat shock proteins. This will make the resistance in the blood circulation less, meaning that the blood vessels will expand, making it easier to run blood through. Therefore patients with heart problems and/or elevated blood pressure are often advised to visit the sauna.
Pain Although there’s not much research on the matter, visiting the sauna does seem to enlighten the pain symptoms in patients suffering from spondylitis (9) and rheumatoid arthritis (8). But if you are experiencing a lot of muscle soreness/pains as an aftereffect of heavy training (weightlifting for example) I would not recommend it. The increase in stress hormones does decrease the inflammation, but the elevated body temperature will do the inflammation no good. This also applies to hot showers and baths. Lowering the inflammation (which is a big cause of the pain) is better done with cold therapy (showers, baths etc.)
Further health benefits?
Lots of them: a lesser chance of getting the cold (5), fewer experienced symptoms in patients suffering from ankylosing spondylitis (9) (a type of arthritis) and rheumatoid arthritis (8); and patients with heart disease show increased ejection fraction and lowered blood pressure (11,12,13,16) (sauna visits are contraindicated with instable angina pectoris, recent heart attack or severe stenosis of the aorta). Furthermore the body adapts to heat making it easier to cope with increased body temperature by better heat regulating mechanisms.
Concluding.
Despite the low volume of research regarding the effects on recovery from exercise training (strength and endurance) and the mechanisms involved, the sauna has a lot to offer for athletes in terms of health benefits. The production of muscle en bone tissue is being stimulated by the elevation in growth hormone. The inflammation gets reduced by the production of growth hormone, heat shock proteins and cortisol. Further-more, research shows an elevation in red blood cells, which results in more capacity for oxygen transportation.
Besides that, upon repeated sauna sessions, the body will be able to cope better with the heat, which has important benefits for performance.
Due to the heat that is produced during training by elevated energy consumption, the body temperature rises which can be a major factor in limiting your performance. So being able to deal better with distributing heat and keep the temperature from rising as much, will give you a great advantage.
Got interested in buying one?
A sauna doesn’t take very much space and is a great investment if you want to increase your performance. Buying a sauna will cost you depending on the size between 700 to 1500 dollar.
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References:
1: Effect of the sauna-induced thermal stimuli of various intensity on the thermal and hormonal metabolism in women.
http://biolsport.com/fulltxt.php?ICID=890538
2: Haemodynamic and hormonal responses to heat exposure in a Finnish sauna bath
http://link.springer.com/article/10.1007/BF02330710
3: Effect of post-exercise sauna bathing on the endurance performance of competitive male runners
4: Response of plasma endorphins, prolactin and catecholamines in women to intense heat in a sauna
http://link.springer.com/article/10.1007/BF00691246
5: Regular Sauna Bathing and the Incidence of Common Colds
http://www.tandfonline.com/doi/abs/10.3109/07853899009148930
6: Endocrine effects of repeated sauna bathing
7: Sauna-Induced Rapid Weight Loss decreases Explosive Power in Women but not in Men
8: Infrared sauna in patients with rheumatoid arthritis and ankylosing spondylitis
http://link.springer.com/article/10.1007/s10067-008-0977-y
9: Effects of thermal therapy combining sauna therapy and underwater exercise in patients with fibromyalgia
http://www.sciencedirect.com/science/article/pii/S1744388110000599
10: Effect of Repeated Sauna Treatment on Exercise Tolerance and Endothelial Function in Patients With Chronic Heart Failure
http://content.onlinejacc.org/article.aspx?articleid=1127811
11: The Effects of Finish Sauna on Hemodynamics of the Circulatory System in Men and Women
12: Beneficial effects of sauna bathing for heart failure patients
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2359619/
13: Effects of Sauna Alone and Postexercise Sauna Baths on Blood Pressure and Hemodynamic Variables in Patients With Untreated Hypertension
http://onlinelibrary.wiley.com/doi/10.1111/j.1751-7176.2012.00637.x/full
14: THE INFLUENCE OF SAUNA TRAINING ON THE HORMONAL SYSTEM OF YOUNG WOMEN
15: Effects of far-infrared sauna bathing on recovery from strength and endurance training sessions in men
https://springerplus.springeropen.com/articles/10.1186/s40064-015-1093-5
16: Combined effects of repeated sauna therapy and exercise training on cardiac function and physical activity in patients with chronic heart failure
http://www.tandfonline.com/doi/abs/10.3109/09638288.2015.1044032
17: Whole-body hyperthermia-induced thermotolerance is associated with the induction of Heat Shock Protein 70 in mice
http://jeb.biologists.org/content/205/2/273.short
18: Invited Review: Heat shock proteins: modifying factors in physiological stress responses and acquired thermotolerance
http://jap.physiology.org/content/92/5/2177.short
19: The Exercise-Induced Stress Response of Skeletal Muscle, with Specific Emphasis on Humans
http://link.springer.com/article/10.2165/00007256-200939080-00003
20: Effect of a Single Finnish Sauna Session on White Blood Cell Profile and Cortisol Levels in Athletes and Non-Athletes
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3916915/
21 Effect of hyperthermia and physical activity on circulating growth hormone
http://www.nrcresearchpress.com/doi/pdf/10.1139/H08-073
22: Exercise-induced hyperthermia and hormonal responses to exercise
http://www.nrcresearchpress.com/doi/abs/10.1139/y98-045#.WCA4fy2LTIU
23: Growth hormone.
https://en.wikipedia.org/wiki/Growth_hormone#cite_note-Molitch_et_al._2006-39
24: METABOLIC AND HORMONAL RESPONSES TO EXOGENOUS HYPERTHERMIA IN MAN
http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2265.1989.tb00271.x/full
25: Unaltered norepinephrine-heart rate relationship in exercise with exogenous heat
http://jap.physiology.org/content/62/2/646.short
26 Heat acclimation: role of norepinephrine in the anterior hypothalamus
http://jap.physiology.org/content/58/6/1923.short
27: 72 kDa Extracellular Heat Shock Protein (eHsp72), Norepinephrine (NE), and the Innate Immune Response Following Moderate Exercise
http://link.springer.com/chapter/10.1007/978-90-481-3381-9_19