WHAT DOES A SAUNA DO?
The list of alleged benefits of regular use of sauna is long, but are they true? We take a look at what science tells us.
Humans all over the world have used saunas and sweat lodges for millennia. The list of reasons to use them is long: Hygiene, health, socialization and spiritual goals.
You can find loads of claims about the positive effects of using a sauna all over the internet. But not all of these alleged benefits have legitimate proof to back them up. So how do you know what is right?
For the past couple of decades, science have been looking into the use of saunas and heat therapy in general. So join us as we take a stroll down Science Lane and separate the rubbish from the truth!
Claim number 1: Reduces muscle and joint pain (and muscle tension)
One of the main claims is that sauna bathing are beneficial for your muscles and joints.
A number of studies have looked into the effects of using a sauna on ailments like arthritis, fibromyalgia (pain in bones, joints and muscles) and other kinds of permanent or frequent aches. The studies all showed a significant reduction in symptoms associated with the disorders. And this was shown both in the test subjects own perception of the symptoms and the objectively measureable data like joint mobility,,.
NOTE: Virtually all of the studies we found regarding muscle and joint pains looked at the effects of infrared saunas. Read more about infrared saunas here.
So sauna users often say they feel more relaxed, comfortable and feel less pain in muscles and joints. And science backs these claims. So let us mark this as TRUE (at least if you use an infrared sauna!)
Claim number 2: Makes you burn more calories
You have probably noticed an increase in your heart rate if you have spent just ten minutes in a sauna. The heated air in the cabin increases your perspiration so your body can get rid of the excess heat. And that increase require the blood to flow around the body faster, ultimately raising your heart rate.
This has an impact on our metabolism as well. That was confirmed in 2019, when a group of scientists tested how the bodies of young men reacted to the use of saunas. The test subjects sat in a sauna for ten minutes at a time followed by a five-minute cool down between each ten-minute segment. The scientists discovered that the metabolism increased during each of the four ten-minute sauna baths. The subjects burned 73 calories on average during the first bath. But by the fourth and final segment, the average caloric consumption had increased to 131 calories. That’s a near 80 percent increase!
In another study, also from 2019, German scientists found out that a 25-minute sauna bath (at approximately 93˚C) put the body through the same cardiovascular stress as if ride a stationary bike at a moderate pace for the same period of time. However, the scientists stress that this does not mean you should use sauna bathing as a strategy for weight loss. Simply because it does not activate the muscles like during physical exercise.
All in all, science seems to back the claim that using a sauna makes you burn more calories. We cannot say how much of an increase you will experience though. That calculation depends on a number of factors like age, body composition and general level of fitness. But we feel confident in marking this claim as TRUE (but it cannot replace working out and eating healthy if you try to lose weight!).
Claim number 3: It is good for the heart
The extreme heat in a sauna increases your heart rate and your blood pressure for a limited period of time. This can be beneficial to your heart.
One of the biggest studies regarding this topic was made in Finland. Back in the late 1980’s, a group of scientists performed a number of tests on more than 2000 middle aged men and women. 20 years later they did a follow up on the same group of people. All of the participants were regular sauna users. The only difference being how often they used it.
The results were clear: The bigger the sauna usage, the lesser the risk of cardiovascular diseases! The group that practiced sauna bathing at least four times a week had a 63% reduction in the risk of sudden cardiac death compared to the group that only visited the sauna once a week. On top of that, the same group had a 40% reduction in all-cause mortality.
The same group of scientists published another paper based on a similar collection of data. In this report they saw a 61% reduction in the risk of stroke, if the individual practiced sauna bathing at least four times a week.
There is sufficient evidence to support the claim that the use of sauna is good for your heart. So let us tick this one as TRUE!
Claim number 4: Boosts the Immune System
Summer is rending and the runny noses and tickling throats announces their arrival. Now it is about giving one’s body a helping hand to keep illness away. And it looks like sauna can give you a boost in the fight against bacteria and virus.
In 2013 a group of scientists found out that the number of white blood cells increased during sauna usage. The young men in the study were divided into two groups, trained and untrained and all the participants showed an increase in the number of white blood cells after a sauna bath. But the increase was most significant in the group of trained men.
We would like to point out, that the increase measured in the untrained group was not “statistically significant”. This means that the results can be attributed to coincidences due to the limited number of participants in the study.
The scientists do not provide a full theory on the potential long term impact of the results. But as white blood cells are part of “the first line of immune defence”, as the scientists put it, we must presume that an increase in the number of these cells provides a stronger Immune System.
So it looks like sauna bathing boosts our bodies defences, especially if we consider the previously confirmed claims. We go out on a limb and mark this claim as TRUE for fit individuals, and possibly true for untrained!
Claim number 5: It is healthy for the brain
A lot of claims regarding the positive effects of using a sauna is about the physical benefits. But it seems that a good sweat in a hot cabin is good for the brain as well.
In 2005 a group of scientists found out that regular sauna bathing had a positive effect on patients with mild depression symptoms. Moreover, the Finnish study, that we touched on above, discovered that the test participants that used saunas at least four times a week, almost every week, had 65% reduced risk of developing Alzheimer’s Disease. The same group also had 66% reduced risk of developing Dementia. These findings are especially interesting due to the enourmous amount of data included in the study.
It seems safe to say that this claim is TRUE, if you do sauna bathing on a regular basis!
Claim number 6: Helps “detox” the body
“Detoxing” is very controversial. The first part of the discussion is whether it is even possible to detoxify your body. The second part of the discussion is how to do it, if it actually is possible? We have found two studies that looked at possible detoxifying effects of sauna bathing. Please note that both of the studies combined a number of alleged detoxifiers, but the use of sauna was the most prominent.
Both studies used questionnaires about the test subjects own perception of the quality of life. The first study found a significant increase in quality of life according to the participants answers to the questionnaires. But the scientists note that the increased care associated with the testing could have affected the test subjects, making them more likely to give positive answers in the follow up-questions.
The second study tested two different kinds of sauna therapy. Once again the scientists discovered that the participants own perception of their health a quality of live increased. But there were no changes in the actual measurements of toxins in the bodies of any of the subjects.
Many of the toxins in our bodies are mainly secreted through the liver and kidneys. It seems doubtful that heat therapy like sauna bathing should have any effect on that process. You can argue that increased blood flow would speed up the processes of the kidneys and liver, but we do not know if that is even possible. We can also point out that sweating does not make you secrete more toxins.
Looking at these results, sauna does not seem to have any detoxifying qualities. Therefore, we mark this claim as FALSE – sauna bathing does NOT detoxify your body!
Claim 7: Increases mobility and flexibility
Heat therapy, such as sauna bathing, has a documented effect on joint mobility and muscle tensions (see “Claim number 1”) in individuals with disorders and ailments. But what about a completely healthy person that just wants to be able to touch his or her own toes?
We found a couple of studies looking into this. One of them found that short yoga sessions could significantly increase the test subjects’ mobility in just eight weeks with one weekly yoga session.
Another very interesting study found that the effect of stretching your muscles increased by more than 200 percent, if done in an infrared sauna. According to the author of the study, it would normally take “weeks of repeated mobility training to achieve this kind of effect”.
Fitness instructors and trainers generally recommend warming up before stretching. This could explain why the effects of stretching in a sauna seems to be so effective. No matter what, we mark this claim as TRUE, but you have to actively stretch in the sauna to reap the benefits.
Claim number 8: Increases your performance
Numerous athletes and fitness enthusiasts use sauna bathing as part of their training regimen. Some gyms even offer their members to relax in a sauna or Steam after their workout. And you CAN actually gain a slight advantage in your hunt for training results if you include the use of sauna in to your training habits.
In 2018 a so-called meta review was written. This is a review of all the available literature and studies surrounding a topic, to get an impression of the overall results instead of the individual studies. 16 papers were reviewed, including studies with other kinds of heat therapy like hot water bathing. The authors found a number of interesting results, the most interesting being:
- Lowering of heart rate when resting,
- Up to two percent increase in performance in endurance running
- Improved ability to keep the core body temperature down, which plays a crucial role when aiming for performance, as it counteracts the risk of e.g. overheating
The authors of the review give a list of recommendations on how to implement heat therapy. We recommend you read the section on “Practical Applications and Recommendations for Athletes” in the review, if you are interested in gaining an edge in your training or competition. You find the entire review here.
In the end we can conclude that this claim is TRUE, even though we still need clarification on the possible differences between using a sauna and hot water bathing.
To sum up…
Most of the studies we refer to in this article is from a huge meta review focusing on the health benefits and physical effects of using sauna. You can find the review right here, but as the authors conclude themselves: “Regular infrared and/or Finnish sauna bathing has the potential to provide many beneficial health effects, especially for those with cardiovascular-related and rheumatological disease, as well as athletes seeking improved exercise performance”.
More research is needed in order to make rock solid conclusions regarding some of the claims. But we still feel safe to say that science confirms a lot of the potential health benefits of sauna bathing shared by users all over the world!