Sauna

The short version

I use a sauna. The best evidence for it is a set of Finnish cohort studies, and they show an association, not proof that sauna caused anything.^1,2
In the biggest one (2,315 men followed for a median of 20.7 years), men who sat in a sauna 4 to 7 times a week for more than 19 minutes did best compared with men who went once a week for under 11 minutes.¹
The randomized evidence is thin: six runners, one small depression trial, and short hormone studies. Nothing here shows sauna extends life.^3,4,5
Real cautions exist: heart conditions, alcohol, and a reversible drop in sperm count and motility.^6,7
Rhonda Patrick, PhD, co-wrote a review of the topic and has covered it for years, so her take gets its own section below.⁸

The protocol

This is what the research used, not a prescription and not a record of my own routine. Where a number comes from Rhonda Patrick talking about the studies, it says so.

Parameter	What the research used	Source
Frequency	4 to 7 sessions a week did best; once a week was the comparison group	^1,9
Session length	Over 19 minutes beat under 11 minutes for sudden cardiac death risk	¹
Temperature	Experiments ran at 80 to 100°C (176 to 212°F); Patrick says the Finnish cohort studies sit around 174 to 179°F (79 to 82°C)	^10,11,12
Timing	The running trial put the sauna right after training, about 89.9°C (194°F) for 31 minutes	³
Alcohol	Avoid it before and during; it raises the risk of low blood pressure, arrhythmia, and sudden death	⁶

Why it works

A session is a heat stress on the heart and the hormones. In eight young men, heart rate rose by about 60% to 130% and norepinephrine by about 100% to 310%, depending on how hot and how long they stayed.¹⁰

Researchers propose that repeated sessions improve how arteries dilate, lower arterial stiffness, shift autonomic nervous system balance, and nudge lipids and blood pressure in a good direction.²

Patrick and her co-author describe repeated sauna use as likely producing hormesis, meaning a dose of stress small enough that the body adapts and comes out ahead.⁸

Heat shock proteins come up a lot in sauna talk. In her January 2026 talk, Patrick describes them as proteins that help other proteins keep their shape and says they stay elevated for about 48 hours after heat or exercise; she ties them to protection against amyloid-beta buildup in mouse models.¹² I have not traced a human trial for that claim for this page, so I treat it as a plausible mechanism, not a result.

What the research says

Moderate Frequent sauna use goes with fewer cardiovascular deaths and fewer deaths overall. In 2,315 Finnish men aged 42 to 60, 4 to 7 sessions a week versus one had a sudden cardiac death hazard ratio of 0.37 (95% CI 0.18 to 0.75), and crude all-cause deaths were 49.1% at one session a week, 37.8% at 2 to 3, and 30.8% at 4 to 7.¹ Another Finnish study of 1,688 men and women (mean age 63) found fatal cardiovascular events fell with frequency too, with a fully adjusted hazard ratio of 0.23 (0.08 to 0.65) at 4 to 7 sessions, while 2 to 3 sessions (0.75, 0.52 to 1.08) was not clearly different from once a week.⁹ The catch is that these are observational studies, all Finnish and sharing authors, so fitter or healthier people may simply sauna more.^1,9

Early Dementia and Alzheimer's disease followed the same pattern in the 2,315-man cohort: hazard ratios of 0.34 (0.16 to 0.71) for dementia and 0.35 (0.14 to 0.90) for Alzheimer's at 4 to 7 sessions a week, with only 204 and 123 cases.¹³ I call this early because it is the same cohort, it has few cases, and 2 to 3 sessions a week showed nothing significant (dementia 0.78, 0.57 to 1.06).¹³

Early Stroke and blood pressure look similar but thinner. For stroke, 1,628 adults had 155 strokes and a hazard ratio of 0.38 (0.18 to 0.81) at 4 to 7 sessions a week.¹⁴ For new high blood pressure, 1,621 men followed for a median of 24.7 years had a fully adjusted hazard ratio of 0.53 (0.28 to 0.98) at 4 to 7 sessions, but the 2 to 3 session group came out at 0.83 (0.59 to 1.18).¹⁵

Early Acute heart effects are real and well documented in small studies. Pushed to discomfort or exhaustion, eight young men had heart rates up by as much as 130%.¹⁰ A review of the field concludes that most healthy adults tolerate the brief cardiovascular and hormonal swings, and that unstable angina, a recent heart attack, and severe aortic stenosis rule it out.⁶

Early Growth hormone rises with heat, but not in a way that matters for a normal routine. In 17 people sitting in an 80°C (176°F) sauna for an hour twice a day for 7 days, men's growth hormone rose 16-fold, and the rise faded after day 3.¹¹ In the eight-man study, growth hormone rose in the 100°C (212°F) session while cortisol fell in the shorter sessions.¹⁰ That is a lot of heat for a hormone blip, and the authors tie it to dehydration.¹¹

Early Post-exercise sauna may help endurance. Six male runners who sat in a sauna after training for 3 weeks (about 12.7 sessions of 31 minutes) lasted 32% longer (90% confidence limits 21% to 43%) in a run to exhaustion, and plasma volume rose 7.1%.³ Six runners over three weeks is a pilot, not a verdict.³

Early Heat for depression has one real randomized trial. In 29 adults with major depressive disorder, a single session of whole-body hyperthermia (a clinical heating procedure, not a backyard sauna) beat a sham by 6.53 points on the Hamilton Depression Rating Scale at week 1 and 4.27 points at week 6.⁴ The catch: 93.8% of the heat group and 71.4% of the sham group guessed they got real heat, so blinding was imperfect.⁴

Mixed Overall quality is uneven. A systematic review found 40 clinical studies with 3,855 participants, only 13 of them randomized, and most with fewer than 40 people.⁵

Rhonda Patrick on sauna

Patrick is the person I read most on this, so here is what I can verify she said, with the limits of what I could open.

She co-authored "Sauna use as a lifestyle practice to extend healthspan" (Patrick and Johnson, Experimental Gerontology, 2021). Its abstract frames sessions as typically running 113 to 212°F (45 to 100°C), repeated use as likely producing hormesis, and the large cohort studies as showing a dose-dependent link to lower morbidity and mortality.⁸ I could read only the abstract, not the full text.

Her FoundMyFitness episodes on the topic:

2015, "Sauna Use and Building Resilience to Stress," where she treats heat as a resilience tool.¹⁶
2017, an interview with Jari Laukkanen, the lead author of the Finnish papers above, on sauna and cardiovascular and Alzheimer's risk.¹⁷
2022, "Sauna Benefits Deep Dive and Optimal Use" with MedCram's Kyle Allred, with segments on her own protocol, hydration, cold therapy, safety, and who should avoid saunas.¹⁸
2025, a chapter on how heat exposure supports resistance training, unlike cold.¹⁹

She has also covered it twice on The Peter Attia Drive, in 2023 (including her personal protocol) and in 2025 (including why hotter may not be better), though those details sit behind a paywall.^20,21

The most specific numbers come from her January 22, 2026 talk on the FoundMyFitness YouTube channel. They come from an auto-generated transcript, so treat the exact figures as approximate:¹²

Studies she cites used roughly 174 to 179°F (79 to 82°C), with humidity from water on hot rocks.
She calls about 20 minutes the sweet spot, with shorter sessions showing a weaker effect, and links 4 to 7 sessions a week to lower risks compared with once a week.
She says she personally uses about 180°F (82°C), suggests about 190°F (88°C) as a ceiling, and advises against 212°F (100°C) saunas.
For infrared she suggests roughly doubling the time, to about 45 to 60 minutes, and she flags that as based on limited data.
She describes a hot bath at about 104°F (40°C) for about 20 minutes as another option, and says sauna combined with exercise looks additive for fitness.

Those are her words about the research and her own body. They are not a sign-off on anything I do.

Sauna and cold together

I use both, so I looked for evidence on the combination. There is not much.

Scandinavian winter swimmers alternate cold dips with sauna. In one small comparison (7 swimmers, 8 controls), the swimmers averaged 11 minutes a week in cold water and 57 minutes a week in sauna heat, and the authors say causality cannot be concluded.²² That 11 minutes is what that group did, not a dose the paper recommends.²²

A meta-analysis of alternating hot and cold water after exercise found less soreness and less strength loss than doing nothing, with little to separate it from other recovery methods, and all 18 trials had a high risk of bias.²³ It tested hot and cold baths, not sauna and plunge.

On ordering, I found no trial that compares sauna-then-cold with cold-then-sauna. The one firm thing is about cold and lifting: cold-water immersion after strength training blunted strength and muscle gains.^24,25 I found no such finding for heat, and a chapter title in one of Patrick's episodes says heat supports resistance training unlike cold.¹⁹ So if cold goes in the mix, the evidence says to keep it away from heavy lifting. That is my reading of the evidence, not a trial result. Patrick's advice in the 2026 talk points the same way: cold on recovery or endurance days, or many hours from lifting.¹²

How I use it

I use a sauna. My own setup, temperature, and schedule go here next; until then, everything above is what the research used, not my routine.

Cautions

Everything on mortality, dementia, stroke, and blood pressure is observational, and healthier people may use saunas more.¹
People with unstable angina, a recent heart attack, or severe aortic stenosis are told to avoid it, and alcohol with sauna raises the risk of low blood pressure, arrhythmia, and sudden death.⁶
Sauna can lower sperm count and motility. In 10 men with normal semen, two 15-minute sessions a week at 80 to 90°C (176 to 194°F) for 3 months strongly impaired both (P < 0.001), and the effects were reversed 6 months after stopping.⁷
Extreme schedules are a different animal. In the hour-twice-a-day study, five of seven women had transient amenorrhea.¹¹
Going to the limit stresses the heart harder: in the eight-man study, the longest session pushed heart rate up about 130%.¹⁰
I am not a doctor, and this is what I read, not medical advice. If you have a heart condition or take blood pressure medication, ask yours first.

References

Laukkanen T, Khan H, Zaccardi F, Laukkanen JA. Association between sauna bathing and fatal cardiovascular and all-cause mortality events. JAMA Internal Medicine. 2015;175(4):542-548.Cohort studyPubMed 25705824 · DOI
What it found: Prospective cohort of 2,315 men aged 42 to 60 in eastern Finland, followed a median of 20.7 years, with 929 deaths. Compared with one sauna session a week, 4 to 7 sessions a week had an adjusted sudden cardiac death hazard ratio of 0.37 (95% CI 0.18 to 0.75), and sessions longer than 19 minutes versus under 11 minutes gave 0.48 (0.31 to 0.75); crude all-cause deaths were 49.1%, 37.8%, and 30.8% at 1, 2 to 3, and 4 to 7 sessions a week.
Limits: Observational, men only, with sauna habits recorded at baseline, so it cannot show that sauna caused the lower risk (fitter or healthier men may sauna more often).
Laukkanen JA, Laukkanen T, Kunutsor SK. Cardiovascular and Other Health Benefits of Sauna Bathing: A Review of the Evidence. Mayo Clinic Proceedings. 2018;93(8):1111-1121.ReviewPubMed 30077204 · DOI
What it found: Narrative review (MEDLINE and EMBASE searched to February 24, 2018) of observational studies and trials linking sauna bathing to lower risk of hypertension, cardiovascular disease, neurocognitive disease, pulmonary disease, and mortality. It proposes mechanisms including better endothelium-dependent dilation, lower arterial stiffness, autonomic nervous system effects, favorable lipid changes, and lower blood pressure.
Limits: A narrative review by the same group that ran the Finnish cohort, so it leans on their observational work and the abstract reports no pooled estimates.
Scoon GSM, Hopkins WG, Mayhew S, Cotter JD. Effect of post-exercise sauna bathing on the endurance performance of competitive male runners. Journal of Science and Medicine in Sport. 2007;10(4):259-262.Randomized trialPubMed 16877041 · DOI
What it found: Crossover trial in six male distance runners: 3 weeks of sauna bathing right after training (about 89.9°C for 31 minutes, 12.7 sessions on average) versus 3 weeks of control training. Time to exhaustion at 5 km pace rose 32% (90% confidence limits 21% to 43%) and plasma volume rose 7.1%, with performance changes tracking plasma volume (r = 0.96).
Limits: Six runners over three weeks, and the abstract I read does not describe randomization or blinding, so treat it as a small pilot.
Janssen CW, Lowry CA, Mehl MR, Allen JJB, Kelly KL, Gartner DE, et al. Whole-Body Hyperthermia for the Treatment of Major Depressive Disorder: A Randomized Clinical Trial. JAMA Psychiatry. 2016;73(8):789-795.Randomized trialPubMed 27172277 · DOI
What it found: Double-blind, sham-controlled trial of one session of whole-body hyperthermia in 29 analyzed adults with major depressive disorder, followed for 6 weeks. The hyperthermia group scored lower on the Hamilton Depression Rating Scale than sham by 6.53 points at week 1 (95% CI -9.90 to -3.16) and 4.27 points at week 6 (-7.94 to -0.61).
Limits: Tiny trial of a clinical heating procedure rather than a home sauna session, and 93.8% of the heat group (versus 71.4% of sham) believed they had received real heat, so blinding was imperfect.
Hussain J, Cohen M. Clinical Effects of Regular Dry Sauna Bathing: A Systematic Review. Evidence-Based Complementary and Alternative Medicine. 2018;2018:1857413.Systematic reviewPubMed 29849692 · DOI
What it found: Systematic review of 40 clinical studies with 3,855 participants, of which only 13 were randomized controlled trials and most had fewer than 40 participants. Most studies reported beneficial effects, and one small study (n = 10) reported reversible disruption of sperm production; the authors call for better data on adverse effects, frequency, and duration.
Limits: Mostly small and varied studies, so it maps the evidence rather than settling any single claim.
Hannuksela ML, Ellahham S. Benefits and risks of sauna bathing. The American Journal of Medicine. 2001;110(2):118-126.ReviewPubMed 11165553 · DOI
What it found: Review concluding that sauna bathing causes brief cardiovascular and hormonal changes that most healthy adults tolerate well. It lists unstable angina, recent myocardial infarction, and severe aortic stenosis as contraindications and warns that alcohol during sauna use raises the risk of hypotension, arrhythmia, and sudden death.
Limits: A narrative review from 2001 with no pooled numbers in the abstract, so the risk statements are expert judgment rather than measured rates.
Garolla A, Torino M, Sartini B, Cosci I, Patassini C, Carraro U, et al. Seminal and molecular evidence that sauna exposure affects human spermatogenesis. Human Reproduction. 2013;28(4):877-885.Lab or mechanistic studyPubMed 23411620 · DOI
What it found: Ten men with normal semen took two 15-minute sauna sessions a week at 80 to 90°C for 3 months. Sperm count and motility were strongly impaired at the end (P < 0.001), and the effects were reversed 6 months after stopping.
Limits: Ten men, no control group, and no men with abnormal semen at baseline, so it shows a reversible effect in healthy men but not how it plays out in men with fertility problems.
Patrick RP, Johnson TL. Sauna use as a lifestyle practice to extend healthspan. Experimental Gerontology. 2021;154:111509.ReviewPubMed 34363927 · DOI
What it found: Review by Rhonda Patrick and Teresa Johnson of sauna practices (sessions typically 45 to 100°C, or 113 to 212°F), the heat-stress response, and health benefits and concerns. It describes repeated sauna use as likely producing hormesis and cites large prospective cohorts linking sauna use to lower morbidity and mortality in a dose-dependent way.
Limits: A narrative review; I could read only the PubMed abstract (the full text was not accessible to me), and the cohort evidence it leans on is observational.
Laukkanen T, Kunutsor SK, Khan H, Willeit P, Zaccardi F, Laukkanen JA. Sauna bathing is associated with reduced cardiovascular mortality and improves risk prediction in men and women: a prospective cohort study. BMC Medicine. 2018;16(1):219.Cohort studyPubMed 30486813 · DOI
What it found: Prospective cohort of 1,688 Finnish adults (mean age 63, 51.4% women) followed a median of 15.0 years, with 181 fatal cardiovascular events. Compared with one session a week, 4 to 7 sessions a week had a hazard ratio of 0.30 (95% CI 0.14 to 0.64) adjusted for age and sex, and 0.23 (0.08 to 0.65) after full adjustment; 2 to 3 sessions was 0.75 (0.52 to 1.08) after full adjustment.
Limits: Observational, so it cannot show that sauna lowered the risk; the 2 to 3 session group was not clearly different from once a week after full adjustment.
Kukkonen-Harjula K, Oja P, Laustiola K, Vuori I, Jolkkonen J, Siitonen S, et al. Haemodynamic and hormonal responses to heat exposure in a Finnish sauna bath. European Journal of Applied Physiology and Occupational Physiology. 1989;58(5):543-550.Lab or mechanistic studyPubMed 2759081 · DOI
What it found: Eight healthy young men did three heat sessions (80°C and 100°C dry heat until discomfort, plus a longer 80°C session to exhaustion). Heart rate rose about 60%, 90%, and 130%, plasma norepinephrine about 100%, 160%, and 310%, and growth hormone rose in the 100°C session while cortisol fell in the two shorter sessions.
Limits: Eight young men in single, push-to-the-limit sessions, so it describes acute stress responses, not long-term effects or what a typical session does.
Leppäluoto J, Huttunen P, Hirvonen J, Väänänen A, Tuominen M, Vuori J. Endocrine effects of repeated sauna bathing. Acta Physiologica Scandinavica. 1986;128(3):467-470.Lab or mechanistic studyPubMed 3788622 · DOI
What it found: Ten healthy men and seven women sat in an 80°C (176°F) sauna for 1 hour twice a day for 7 days. Men's growth hormone rose 16-fold and prolactin 2.3-fold, but the growth hormone rise faded after day 3; cortisol and ACTH fell, and five of seven women had transient amenorrhea.
Limits: Seventeen people, a far heavier schedule than anyone uses at home, and the authors tie the hormone changes to dehydration; it shows no health outcome.
Patrick R. Dr. Rhonda Patrick: Maximizing Healthspan with Exercise, Sauna, & Cold Exposure. FoundMyFitness (YouTube), January 22, 2026.VideoWatch
What it found: A talk by Rhonda Patrick, followed by audience questions, covering exercise, sauna, and cold exposure; in it she gives the sauna and cold doses she bases on studies and says what she uses herself (about 180°F for sauna, about 50°F for 2 minutes for cold).
Limits: I read an auto-generated transcript on a third-party mirror (rosetta.to), because the YouTube page itself would not load for me; the title and channel were confirmed through YouTube's oEmbed, the date comes from the mirror, and the transcript was cut off partway through the Q&A. Title, channel, and the January 22, 2026 date were confirmed on YouTube; the figures quoted come from an auto-generated transcript.
Laukkanen T, Kunutsor S, Kauhanen J, Laukkanen JA. Sauna bathing is inversely associated with dementia and Alzheimer's disease in middle-aged Finnish men. Age and Ageing. 2017;46(2):245-249.Cohort studyPubMed 27932366 · DOI
What it found: Prospective cohort of 2,315 men aged 42 to 60 followed a median of 20.7 years, with 204 dementia cases and 123 Alzheimer's cases. Compared with one session a week, 4 to 7 sessions a week had a dementia hazard ratio of 0.34 (95% CI 0.16 to 0.71) and an Alzheimer's hazard ratio of 0.35 (0.14 to 0.90); 2 to 3 sessions a week was not significant (0.78, 0.57 to 1.06, for dementia).
Limits: Observational, men only, relatively few cases, and the same Finnish cohort as the mortality paper, so it is not an independent confirmation and cannot show causation.
Kunutsor SK, Khan H, Zaccardi F, Laukkanen T, Willeit P, Laukkanen JA. Sauna bathing reduces the risk of stroke in Finnish men and women: A prospective cohort study. Neurology. 2018;90(22):e1937-e1944.Cohort studyPubMed 29720543 · DOI
What it found: Prospective cohort of 1,628 Finnish adults aged 53 to 74 with no stroke history, followed a median of 14.9 years, with 155 strokes. Compared with one session a week, 4 to 7 sessions a week had a hazard ratio of 0.39 (95% CI 0.18 to 0.83) adjusted for age and sex, and 0.38 (0.18 to 0.81) after adding physical activity and socioeconomic status.
Limits: Observational with a modest number of strokes (only 34 hemorrhagic), so subgroup results are imprecise and causation is not shown.
Zaccardi F, Laukkanen T, Willeit P, Kunutsor SK, Kauhanen J, Laukkanen JA. Sauna Bathing and Incident Hypertension: A Prospective Cohort Study. American Journal of Hypertension. 2017;30(11):1120-1125.Cohort studyPubMed 28633297 · DOI
What it found: Prospective cohort of 1,621 Finnish men aged 42 to 60 without hypertension at baseline, followed a median of 24.7 years, with 251 new cases (15.5%). Compared with one session a week, 4 to 7 sessions a week had a hazard ratio of 0.54 (95% CI 0.32 to 0.91), or 0.53 (0.28 to 0.98) after full adjustment; 2 to 3 sessions was 0.76 (0.57 to 1.02), and 0.83 (0.59 to 1.18) after full adjustment.
Limits: Observational and men only; the confidence intervals for the top group sit close to 1.0, and the 2 to 3 session group showed no clear benefit.
Patrick R. #014 Sauna Use and Building Resilience to Stress with Dr. Rhonda Patrick. FoundMyFitness, September 11, 2015.PodcastListen
What it found: An early FoundMyFitness episode in which Patrick treats heat stress as a way to build resilience, touching on heart disease risk, endurance, muscle, mood, and removal of metals.
Limits: I read only the entry in the publisher's feed, not a transcript, and it is a 2015 episode that predates the 2017 to 2018 Finnish cohort papers.
Patrick R, Laukkanen J. #037 Dr. Jari Laukkanen on Sauna Use for the Prevention of Cardiovascular & Alzheimer's Disease. FoundMyFitness, June 15, 2017.PodcastListen
What it found: Rhonda Patrick interviews Jari Laukkanen, lead author of the Finnish sauna cohort papers, about sauna and cardiovascular and Alzheimer's risk; the show notes mention heart rate rising to 150 beats per minute and a chapter on adding cold-water immersion to the sauna.
Limits: I read only the show-note entry in the publisher's feed, not a transcript, so I cannot say what either speaker said about doses beyond the topics listed.
Patrick R, Allred K. #073 Sauna Benefits Deep Dive and Optimal Use with Dr. Rhonda Patrick & MedCram. FoundMyFitness, April 13, 2022.PodcastListen
What it found: Rhonda Patrick is interviewed by MedCram co-founder Kyle Allred; the show notes list segments on heat as an exercise mimetic, heat shock proteins and dementia, depression, BDNF, her own sauna protocol (duration, temperature, humidity, frequency), hydration, cold therapy, sauna safety, and who should avoid saunas.
Limits: I read the show notes on the publisher's Libsyn directory page, not a transcript, so the notes list the topics but I did not read her numbers from this episode.
FoundMyFitness. #098 How to Train According to the Experts. FoundMyFitness, February 3, 2025.PodcastListen
What it found: A long training episode whose chapter list includes 'How sauna use improves cardiorespiratory fitness' and 'Why heat exposure supports resistance training, unlike cold.'
Limits: I read only the chapter titles in the publisher's feed, so I can say the topic is covered but not what was said or by whom.
Attia P, Patrick R. #252 ‒ Latest insights on Alzheimer's disease, cancer, exercise, nutrition, and fasting | Rhonda Patrick, Ph.D. The Peter Attia Drive, May 1, 2023.PodcastListen
What it found: Peter Attia's second conversation with Rhonda Patrick; the show notes include a segment on possible brain benefits of sauna and her personal protocol at 1:09:30.
Limits: The detailed show notes are behind a membership paywall, so I confirmed the topic but not what she said.
Attia P, Patrick R. #369 ‒ Rethinking protein needs for performance, muscle preservation, and longevity, and the mental and physical benefits of creatine supplementation and sauna use | Rhonda Patrick, Ph.D. The Peter Attia Drive, October 20, 2025.PodcastListen
What it found: Peter Attia's third conversation with Rhonda Patrick; the preview lists sauna as an exercise mimic that may help cardiovascular and brain health and mood, plus a segment on dementia risk and why hotter may not be better.
Limits: Only the preview is public (the rest is behind a membership paywall), so I confirmed the topics but did not read any temperatures or durations from this episode.
Søberg S, Löfgren J, Philipsen FE, Jensen M, Hansen AE, Ahrens E, et al. Altered brown fat thermoregulation and enhanced cold-induced thermogenesis in young, healthy, winter-swimming men. Cell Reports Medicine. 2021;2(10):100408.Cross-sectional studyPubMed 34755128 · DOI
What it found: Comparison of 7 winter-swimming men (about 2.6 swims a week, who also used sauna) with 8 controls. Swimmers had lower core temperature and larger cold-induced increases in thermogenesis and supraclavicular skin temperature, while brown fat glucose uptake in the cold rose about the same as in controls; their group average was 11 minutes a week in cold water and 57 minutes a week in sauna heat (Table 1).
Limits: Seven swimmers versus eight controls, men only, and the authors say causality cannot be concluded; the 11 minutes a week is what this group did, not a dose the paper recommends.
Bieuzen F, Bleakley CM, Costello JT. Contrast water therapy and exercise induced muscle damage: a systematic review and meta-analysis. PLoS ONE. 2013;8(4):e62356.Meta-analysisPubMed 23626806 · DOI
What it found: Meta-analysis of 18 trials (13 pooled) of contrast water therapy, alternating hot and cold water, after exercise. Compared with passive recovery it improved muscle soreness and reduced strength loss at every follow-up from under 6 hours to 96 hours, but showed little difference from other common recovery methods.
Limits: All 18 trials had a high risk of bias, and it tested alternating hot and cold water baths after hard exercise, not sauna followed by a plunge.
Roberts LA, Raastad T, Markworth JF, Figueiredo VC, Egner IM, Shield A, et al. Post-exercise cold water immersion attenuates acute anabolic signalling and long-term adaptations in muscle to strength training. The Journal of Physiology. 2015;593(18):4285-4301.Randomized trialPubMed 26174323 · DOI
What it found: In 21 active men who strength trained twice a week for 12 weeks, 10 minutes of cold water immersion after each session produced smaller strength and muscle gains than active recovery (for example, type II fiber area rose 17% with active recovery and not with cold). A second study of 9 men found cold immersion blunted the satellite cell and p70S6 kinase response after a single leg workout.
Limits: Small trials in young active men using a 10-minute immersion after every session, so it does not tell us what occasional cold exposure far from a workout does.
Malta ES, Dutra YM, Broatch JR, Bishop DJ, Zagatto AM. The Effects of Regular Cold-Water Immersion Use on Training-Induced Changes in Strength and Endurance Performance: A Systematic Review with Meta-Analysis. Sports Medicine. 2021;51(1):161-174.Meta-analysisPubMed 33146851 · DOI
What it found: Meta-analysis of 8 articles on regular cold-water immersion (15°C or colder) alongside training. With resistance training it hurt strength outcomes (overall standardized mean difference -0.60; 95% CI -0.87 to -0.33) and ballistic performance (-0.61; -1.11 to -0.11); with endurance training it had no effect on maximal aerobic power (-0.07) or time-trial performance (0.00).
Limits: Only 8 articles, mostly small trials in healthy, trained or active adults, so the size of the effect is uncertain even though the direction is consistent.