I have recently been posting a lot of photos of myself sitting in an infrared sauna at my local yoga studio. It probably comes at a surprise to the Brisbane community as the average temperature here has been 30 degrees + every day for the last 2 weeks!! But since moving to the area, I have been going twice a week to sit in the infra red sauna set to 60 degrees celsius for 30 minutes…. & I love it! I started to ask myself, why I love the sauna experience so much, seeing as most might find it counterintuitive to sit in a hot room when outside might just do the trick! Once I thought about it I realised there is not only the obvious relaxation I get while I am in the sauna but after, there is a re-energizing feeling. So I decided to do some research to see if there was some scientific evidence to back up my feelings.
The use of saunas isn’t new. Humans have been doing it since the middle ages around Europe. In particular the people in the Scandinavian regions such as Finland love it and they are as common as the family car. In fact going down the research rabbit hole I read a statistic that said there are 5 million inhabitants in Finland and 3 million saunas which averages out to be 1 per household. It makes sense, it gets cold in places like Finland but I really feel there is more to saunas then just keeping warm.
Before we go into seeing what the evidence says lets think about what happens physiologically. When we sit in a sauna our body endures thermal stress and as a result the following happens:
- Heart rate increases
- Cardiac output (the amount of blood that the heart pumps through the circulatory system in a minute) increases
- There is an increase in peripheral resistance and increasing circulation (arteries dilate decreasing the pressure needed for the blood to flow through them)
- There can be a decrease in blood pressure
- Metabolic rate increases
Do these effects sound familiar? I mean if you went for a brisk walk with your dog the physiological effects would be similar! But don’t get me wrong there is really nothing that can replace regular exercise but it makes sense that it would be great as an adjunct therapy!
Historically there has been a small amount of low quality evidence that has shown that the use of regular saunas can assist with respiratory function to those who have asthma and bronchitis (although contraindicated in acute respiratory infection). The use of sauna in these individuals resulted in an increase in Forced Vital Capacity (the total amount of air exhaled during the Forced Expiratory Volume test), Peak expiratory flow (maximum speed of expiration) and Forced expiratory volume (forced expiratory volumes that a person can do in 1 second).
A study that looked at 2315 middle aged Finnish men over a 20 year period, showed that regular sauna use (4-7 days a week) could in fact extend your life span. The study showed that an increase frequency of sauna use is associated with a decrease risk of coronary heart disease (CHD), cardiovascular disease (CD) and all causes of mortality. The researchers suspect this happens because there is a physiological effect that is similar to low to medium intensity physical exercise, such as, an increase in heart rate up to 100-150 beats per minute. With repeated treatments there is an improvement of endothelial function (the endothelial is a thin membrane that lines the inside of the heart and blood vessels) in patients with CHD and therefore there it could have a preventative role in improving the integrity of our blood vessels.
What about the use of saunas for exercise and sports recovery?
A very small study looking at male distance runners found that using a sauna after exercise resulted in an increase in blood volume and as a result an improvement in their endurance running performance. After 3 weeks of using saunas after exercise they could run 32% further before exhaustion.
As well as all the changes in circulation there was also an experiment with rats that showed intermittent heating releases specific proteins called heat shock proteins. What the researchers found was that when the rats were immobilised (not using their muscles) and then mobilised and heated the heating improved muscle growth up to 30%.
Now with most of the literature out there, confounders make it very difficult to confidently make definite statements about correlations and because of this there is always a need for more research. If you unsure if it is safe to use a sauna regularly then check with your health professional first otherwise give it a go and see how it feels for yourself.
- Laukkanen, T., Khan, H., Zaccardi, F., & Laukkanen, J. A. (2015). Association Between Sauna Bathing and Fatal Cardiovascular and All-Cause Mortality Events. JAMA Internal Medicine, 175(4), 542. doi:10.1001/jamainternmed.2014.8187
- Crinnion, W. (2011). Sauna as a Valuable Clinical Tool for Cardiovascular, Autoimmune, Toxicant- induced and other Chronic Health Problems. Altern Med Rev,16(3):215-225 .
- Scoon, G. S. M., Hopkins, W. G., Mayhew, S., & Cotter, J. D. (2007). Effect of post-exercise sauna bathing on the endurance performance of competitive male runners. Journal of Science and Medicine in Sport, 10(4), 259–262. doi:10.1016/j.jsams.2006.06.009
- Selsby, J. T., Rother, S., Tsuda, S., Pracash, O., Quindry, J., & Dodd, S. L. (2007). Intermittent hyperthermia enhances skeletal muscle regrowth and attenuates oxidative damage following reloading. Journal of Applied Physiology, 102(4), 1702–1707. doi:10.1152/japplphysiol.00722.2006