The short answer
There are hints of benefit, from very small studies. Six runners who used a sauna after training for three weeks ran 32% longer before exhaustion, probably because their blood volume rose. Ten men recovered jump height slightly better after an infrared sauna. Larger trials are needed, and dehydration is the main risk.
Weak evidence
Small or short studies, surveys, or results that are mixed. How we grade
On this page
Can a sauna improve endurance?
The study most often quoted is from New Zealand in 2007. Six competitive male distance runners did three weeks of their normal training with a sauna straight afterwards, and three weeks without, in random order. The sauna was humid, about 90°C, and they stayed in for about 30 minutes, around 13 times in total.
After the sauna weeks, they could run at their 5 km race pace for 32% longer before exhaustion, which the authors estimated would be worth about 2% in a race. Their plasma volume, the liquid part of the blood, rose by about 7%, and the bigger the rise, the bigger the improvement. More plasma means the heart can pump more blood with each beat and the body can sweat more freely, a bit like heat training before a race in a hot country.
Six people is a very small study. Treat it as a promising idea, not proof.
What about recovery after a hard session?
A Finnish study tested a far-infrared sauna in ten active men after a strength or endurance workout. After the endurance session, the men’s jump height had recovered slightly more 30 minutes later if they had sat in the infrared sauna than if they hadn’t. After the strength session, there was no difference. The infrared sauna was mild, at 35°C to 50°C, and felt easier than a traditional one: heart rate afterwards was lower.
Does a sauna make you fitter?
In a Finnish randomised trial, 47 inactive adults with heart risk factors exercised for 8 weeks, with or without a 15-minute sauna afterwards. Those who added the sauna gained a little more aerobic fitness, about 2.7 ml/kg/min of oxygen uptake, than those who only exercised. Exercise still did most of the work.
How should you use a sauna after training?
- Rehydrate first, especially after a long or hot session, and drink again afterwards. See hydration.
- Start with 10 to 15 minutes and build up if you feel fine.
- Don’t use it to “sweat out” weight before a weigh-in. Rapid weight loss through dehydration is dangerous.
- If you like cold water after training, see cold plunges: it may blunt muscle gains from strength training.
There’s more practical detail in using a sauna after the gym.
Keep reading
- Can a sauna help your lungs or prevent colds?
Saunas and respiratory health: what Finnish studies found on pneumonia and lung disease, and whether a sauna can stop a cold.
Weak - Is a sauna good for your skin?
What the research says about saunas and skin: hydration, barrier function, acne, eczema and psoriasis, and what to watch out for.
Weak - Do saunas detox you or help you lose weight?
Sauna detox and weight loss claims, checked: what is in sweat, how much weight you lose in a session and why it comes straight back.
None
Common questions
Should I use a sauna before or after a workout?
After. A hot sauna before exercise raises your heart rate and body temperature and can leave you dehydrated, which hurts performance. The studies that found benefits used the sauna after training.
Does a sauna help with muscle soreness?
Probably not much. The best evidence for soreness is for cold water immersion and hot-and-cold contrast, both of which beat doing nothing by a small amount in trials.
Does a sauna build muscle?
There is no good evidence that it does in people. Claims about growth hormone and heat shock proteins come from short-term blood tests and animal studies, not trials measuring muscle.
References
- Scoon GS et al. Effect of post-exercise sauna bathing on the endurance performance of competitive male runners. Journal of Science and Medicine in Sport, 2007.pubmed.ncbi.nlm.nih.gov
- Mero A et al. Effects of far-infrared sauna bathing on recovery from strength and endurance training sessions in men. SpringerPlus, 2015.pubmed.ncbi.nlm.nih.gov
- Lee E et al. Effects of regular sauna bathing in conjunction with exercise on cardiovascular function: a multi-arm, randomized controlled trial. American Journal of Physiology, 2022.pubmed.ncbi.nlm.nih.gov
- Hussain J, Cohen M. Clinical effects of regular dry sauna bathing: a systematic review. Evidence-Based Complementary and Alternative Medicine, 2018.pubmed.ncbi.nlm.nih.gov
First published 4 November 2026. Spotted an error? Tell us and we'll correct it. Read our editorial policy.