Sauna for Recovery: Why Athletes Use Heat Therapy

Quick Answer

Plenty of athletes finish a session with a sauna, and there is a sensible logic to it. The best known study on the idea, a small trial by Scoon and colleagues in 2007, found that post-exercise sauna use improved endurance run time in a handful of competitive male runners, alongside an increase in plasma volume. It is a promising early finding rather than a settled result, because the study was very small. The recovery-related benefits people describe, from muscle repair to reduced soreness, are mostly based on plausible mechanisms that have not been confirmed in athletes. Heat is a low-risk addition to a recovery routine for most healthy people, but it is not a shortcut, and the honest picture is more modest than the usual headlines. For the wider evidence base, see our Evidence-Based Review of Sauna Therapy.

Why Athletes Reach for Heat

Heat exposure raises core temperature, increases heart rate and pushes blood toward the skin to help you cool down. Your body responds to that stress in ways that overlap with some of the adaptations from training itself, which is the reason researchers have taken an interest. The important thing to hold onto is that overlap in a mechanism is not the same as a measured performance gain. A lot of the sauna and recovery story is built on the first and thin on the second.

The Scoon et al. (2007) Study

The most cited study on sauna and athletic performance was published by Scoon, Hopkins, Mayhew and Cotter in the Journal of Science and Medicine in Sport in 2007. It looked at what happened when competitive male distance runners added post-exercise sauna to their training for three weeks.

Study Design

• Participants: six competitive male distance runners
• Protocol: post-exercise sauna bathing, around four sessions per week for three weeks
• Sauna conditions: roughly 87 degrees C, about 30 minutes per session
• Timing: immediately after training

Key Results

The 32% figure sounds large, and it gets quoted a lot, but it needs context. This was a study of six people with no separate control group, so the result carries real uncertainty. The much smaller time-trial improvement of about 1.9% is arguably the more useful number, because time to exhaustion tends to swing widely from day to day. Treat this as a single small study that is worth building on, not as proof of a fixed effect. It has not, as far as we are aware, been replicated in a large trial. (PMID: 16877041)

Plasma Volume: The Proposed Mechanism

The mechanism most often put forward to explain the Scoon result is plasma volume expansion. The reasoning goes like this. Sauna heat makes you sweat and lose fluid, and the body responds by holding onto more sodium and water and increasing blood proteins that keep fluid inside the vascular compartment. After you rehydrate, total plasma volume can end up a little higher than before. More blood volume can mean better cardiac filling and oxygen delivery, which matters for endurance.

Scoon and colleagues did measure a plasma volume increase of about 7.1% in their runners (PMID: 16877041). That part is real, if small in sample size. What is less certain is how reliably that translates into race-day performance across different athletes, training states and sauna protocols. People often compare this to altitude training. It is a reasonable analogy for how the body adapts to a stressor, but it is an analogy, not evidence that the two produce equivalent results.

Heat Shock Proteins and Muscle Recovery

Heat also triggers what is called the heat shock response, in which cells produce heat shock proteins. In laboratory work these proteins help refold stressed or damaged proteins and are involved in protecting cells under load, which is why they come up in discussions of muscle recovery.

Here is the honest limit. The specific magnitudes and downstream effects often quoted online, including claims about particular proteins protecting muscle fibres or activating muscle stem cells, come from cell and animal studies, not from trials showing faster recovery in trained athletes using a sauna. So the fair way to describe this is as a biologically plausible pathway that is still being studied, rather than a demonstrated recovery benefit you can count on. If it helps, it is likely to be a modest contributor alongside sleep, nutrition and sensible training load.

Sauna, Soreness and Cold Water Comparisons

Delayed onset muscle soreness is the stiffness and pain that shows up a day or two after unfamiliar or hard training. The direct evidence for sauna reducing that soreness is thin, so be cautious with confident claims either way.

The better-studied heat-versus-cold picture is actually about cold water immersion. A Cochrane review found that cold water immersion modestly reduces muscle soreness compared with passive rest in the days after exercise, though the authors rated the evidence quality as low (PMID: 22336838). That is worth knowing, but there is a catch for strength athletes. A controlled trial found that regularly using cold water immersion after resistance training over 12 weeks produced smaller gains in strength and muscle mass than active recovery, and blunted some of the signalling involved in muscle growth (PMID: 26174323). In other words, aggressively chilling down after every strength session may cost you adaptation. That is one reason some strength athletes prefer heat or simply active recovery. It is a comparison worth understanding, not a green light to claim sauna beats cold for soreness, because that specific head-to-head has not been settled.

Sauna, Strength and Hypertrophy

The evidence for sauna directly building strength or muscle is limited, and this is where a lot of overstatement creeps in. A few points that get repeated deserve softening.

Growth Hormone

You will often read that sauna produces large multiples of growth hormone. Heat exposure can acutely change several hormones, but we are not citing a specific figure here because the commonly quoted numbers are not well supported for athletic outcomes, and short-term hormone spikes do not reliably translate into measurable muscle growth. The honest position is that this is an area of interest, not an established muscle-building pathway.

Muscle Preservation During Downtime

There is laboratory and animal work suggesting heat can help limit muscle loss during immobilisation. It is an interesting idea for injured athletes, but it has not been confirmed in a way that supports a firm recommendation for people, so treat it as a hypothesis under investigation rather than an established anti-catabolic tool.

Insulin Sensitivity and Nutrient Handling

Heat exposure is being studied for effects on how the body handles glucose, which in theory could help with recovery nutrition. We are not attaching a specific percentage improvement here, because a reliable athlete-specific figure is not available. Keep this filed under plausible mechanism, not measured benefit.

Sleep and Recovery

Sleep is genuinely one of the most important recovery tools an athlete has, and there is a reasonable case that passive heating before bed can help you fall asleep. A systematic review of warm-water bathing and showering before bed found improvements in how quickly people fell asleep and in sleep quality (PMID: 31102877). That evidence is for warm baths and showers rather than saunas, so applying it to sauna is a sensible inference rather than a direct finding. If an evening sauna leaves you relaxed and helps you wind down, that is a plausible indirect recovery benefit. For a fuller treatment, see our Sauna and Sleep guide.

Heat Acclimatisation for Hot Competition

If you are racing in genuine heat, whether that is a summer marathon or a warm-climate triathlon, getting your body used to heat beforehand is a well established idea. The classic approach is training in hot conditions for a week or two, which can improve sweating, plasma volume and how comfortably you work in the heat. Sauna is sometimes used as a stand-in when training in hot conditions is not practical, and the logic is reasonable. What we cannot do here is give you a precise sauna dose that guarantees competition benefit, because the specific protocols have not been pinned down well enough to promise a result. Think of it as a supporting tool for heat readiness, applied sensibly and with good hydration.

When to Use Sauna: Timing for Athletes

Practical Protocols

These are sensible starting points drawn from how the studies and common practice line up. They are not guarantees of performance, and hydration matters throughout.

Endurance-Style Protocol (Based on Scoon)

General Recovery Protocol

Evidence Summary Table

Safety

Sauna is safe for most healthy people, but it is not for everyone. Skip it or check with your doctor first if you are pregnant, have heart disease, low blood pressure, or any condition affected by heat. Do not combine sauna with alcohol. Come out if you feel dizzy, unwell or lightheaded, keep sessions moderate while you get used to the heat, and rehydrate properly afterwards. For a full run-through, see our Sauna Safety guide.

This article is general information, not medical advice. It is not a substitute for guidance from a qualified health professional. Talk to your doctor before starting sauna use, especially if you have an existing health condition or are training at a high level.

Frequently Asked Questions

Can sauna really improve athletic performance?

There is one small study, Scoon et al. (2007), where post-exercise sauna improved endurance in six competitive male runners, alongside a rise in plasma volume (PMID: 16877041). It is an encouraging early result, but six people is not enough to call it settled, and it has not been confirmed in a large trial. Treat sauna as a low-risk thing to try rather than a guaranteed performance boost.

When should athletes use the sauna?

Soon after training or in the evening on easy days both make sense. Avoid it right before hard sessions or on competition day, mainly because of fluid loss and added cardiovascular load. Consistent, moderate use with good hydration is the sensible pattern.

How long before I might notice anything?

The Scoon study ran for three weeks, so if you are trialling it for endurance, give it around that long before judging. Any effect is likely to be modest, so do not expect a dramatic change.

Is sauna better for endurance or strength athletes?

The little direct evidence there is leans toward endurance, through possible blood volume effects. For strength athletes the direct case is weaker, though there is an interesting related finding that heavy use of cold water immersion after lifting can reduce gains (PMID: 26174323), which is one reason some lifters favour heat or plain active recovery instead.

Does sauna help with muscle recovery?

Possibly, but mostly through indirect routes such as helping you relax before sleep. The cellular recovery pathways people cite are plausible but not yet shown to speed recovery in athletes, so keep expectations grounded.

References

• Scoon GSM, Hopkins WG, Mayhew S, Cotter JD (2007). Effect of post-exercise sauna bathing on the endurance performance of competitive male runners. Journal of Science and Medicine in Sport. PMID: 16877041
• Bleakley C, McDonough S, Gardner E, et al. (2012). Cold-water immersion (cryotherapy) for preventing and treating muscle soreness after exercise. Cochrane Database of Systematic Reviews. PMID: 22336838
• Roberts LA, Raastad T, Markworth JF, et al. (2015). Post-exercise cold water immersion attenuates acute anabolic signalling and long-term adaptations in muscle to strength training. The Journal of Physiology. PMID: 26174323
• Haghayegh S, Khoshnevis S, Smolensky MH, Diller KR, Castriotta RJ (2019). Before-bedtime passive body heating by warm shower or bath to improve sleep: a systematic review and meta-analysis. Sleep Medicine Reviews. PMID: 31102877