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Sauna Hype°H

The claim

“Sauna helps you build and keep muscle.”

Stretched. Heating one muscle for hours a day slowed its loss in immobilized legs and gave small strength gains in some trials. The one sauna trial that measured muscle growth found no extra gain from post-workout infrared sessions.

Updated Sep 24, 2026 · 2 studies reviewed

The claim pulls a real finding well past what the study showed.

People say it in places like these

  • Rhonda Patrick's FoundMyFitness

    Heat treatment cut muscle loss by 37% in people and by up to 32% in rats.

    See an example ↗

  • Rhonda Patrick on Huberman Lab

    Heat stress can cut muscle atrophy by almost 40%.

    See an example ↗

The research found this

The clearest human result is about keeping muscle. Researchers immobilized one leg in each of 23 healthy adults for 10 days. Two hours a day of deep heat from a shortwave diathermy device cut the shrinkage of the heated muscle from 7.6% with a sham treatment to 4.5%.Source 1 · Clinical trialDaily heat treatment maintains mitochondrial function and attenuates atrophy in human skeletal muscle subjected to immobilizationHafen PS, Abbott K, Bowden J, et al.. Journal of Applied Physiology, 2019.Read the paper ↗PubMed ↗ Loss in the individual muscle fibers fell from 10.8% to 5.8%, and the device raised muscle temperature by 4.2°C.

Building muscle with local heat gives mixed results. Eight men wore a heat-generating sheet on the thigh for 8 hours a day, four days a week. After 10 weeks their knee-extension force was up 5.8%, and the muscle's cross-sectional area had grown 2.7% to 6.1%.Source 2 · Clinical trialResponses of muscle mass, strength and gene transcripts to long-term heat stress in healthy human subjectsGoto K, Oda H, Kondo H, et al.. European Journal of Applied Physiology, 2011.Read the paper ↗PubMed ↗ The abstract doesn't say what the heated leg was compared with. A heated garment worn 90 minutes a day raised peak torque (a measure of strength) without enlarging muscle fibers.Source 3 · Clinical trialEffects of repeated local heat therapy on skeletal muscle structure and function in humansKim K, Reid BA, Casey CA, et al.. Journal of Applied Physiology, 2020.Read the paper ↗PubMed ↗ Calf heat pads worn 8 hours a day for six weeks changed nothing.Source 4 · Clinical trialSix weeks of localized heat therapy does not affect muscle mass, strength and contractile properties in healthy active humansLabidi M, Ihsan M, Behan FP, et al.. European Journal of Applied Physiology, 2021.Read the paper ↗PubMed ↗

Heat added to training did no better in the trials that combined them. Ten untrained adults heated one thigh during and after 30 knee-extension sessions, and lean mass rose 15% in both legs.Source 5 · Clinical trialNo clear benefit of muscle heating on hypertrophy and strength with resistance trainingStadnyk AMJ, Rehrer NJ, Handcock PJ, et al.. Temperature, 2018.Read the paper ↗PubMed ↗ In a study of 40 female athletes, half took 10 minutes of infrared sauna at 50°C after training three times a week. Over six weeks they gained as much muscle as the athletes who skipped it, and their loaded jumps improved more.Source 6 · Clinical trialEffects of repeated use of post-exercise infrared sauna on neuromuscular performance and muscle hypertrophyAhokas EK, Hanstock HG, Kyröläinen H, et al.. Frontiers in Sports and Active Living, 2025.Read the paper ↗PubMed ↗

Hot water hasn't helped older muscles either. In a crossover trial, middle-aged and older adults spent six weeks taking hour-long hot baths and six weeks without them. The baths held rectal temperature at 38.5–39.0°C, and quadriceps strength didn't improve. Grip strength fell compared with the control period.Source 7 · Crossover trialEffect of repeated hot water immersion on muscle strength, power, function and physical activity in healthy older adults: A randomised crossover trialPiccolo DD, Corbett J, Exell TA, et al.. Experimental Physiology, 2026.Read the paper ↗PubMed ↗

Much of the confidence in heat for muscle comes from animals. Rats heated before eight days of hind-limb unloading lost less muscle.Source 8 · Animal studyHeat stress attenuates skeletal muscle atrophy in hindlimb-unweighted ratsNaito H, Powers SK, Demirel HA, et al.. Journal of Applied Physiology, 2000.Read the paper ↗PubMed ↗ In a 2020 meta-analysis, the only pooled effect was more muscle mass seven days after heating, and it came from animal studies. The authors called the human evidence preliminary.Source 9 · Meta-analysisEffects of passive heating intervention on muscle hypertrophy and neuromuscular function: A preliminary systematic review with meta-analysisRodrigues P, Trajano GS, Wharton L, et al.. Journal of Thermal Biology, 2020.Read the paper ↗PubMed ↗

The dial reads 65°H for four reasons

How the reading adds up

15 + 18 + 16 + 16 = 65°H

  1. EvidenceWhat kind of human evidence exists?

    15/25

    Most human trials heated one muscle with a local device, and many ran for hours a day.Source 2 · Clinical trialResponses of muscle mass, strength and gene transcripts to long-term heat stress in healthy human subjectsGoto K, Oda H, Kondo H, et al.. European Journal of Applied Physiology, 2011.Read the paper ↗PubMed ↗Source 3 · Clinical trialEffects of repeated local heat therapy on skeletal muscle structure and function in humansKim K, Reid BA, Casey CA, et al.. Journal of Applied Physiology, 2020.Read the paper ↗PubMed ↗Source 4 · Clinical trialSix weeks of localized heat therapy does not affect muscle mass, strength and contractile properties in healthy active humansLabidi M, Ihsan M, Behan FP, et al.. European Journal of Applied Physiology, 2021.Read the paper ↗PubMed ↗Source 1 · Clinical trialDaily heat treatment maintains mitochondrial function and attenuates atrophy in human skeletal muscle subjected to immobilizationHafen PS, Abbott K, Bowden J, et al.. Journal of Applied Physiology, 2019.Read the paper ↗PubMed ↗ The one sauna trial of muscle growth used 10 minutes of infrared after training.Source 6 · Clinical trialEffects of repeated use of post-exercise infrared sauna on neuromuscular performance and muscle hypertrophyAhokas EK, Hanstock HG, Kyröläinen H, et al.. Frontiers in Sports and Active Living, 2025.Read the paper ↗PubMed ↗

  2. ConsistencyHave other studies found the same thing?

    18/25

    Local heat added strength in two of the four trials that tested it.Source 2 · Clinical trialResponses of muscle mass, strength and gene transcripts to long-term heat stress in healthy human subjectsGoto K, Oda H, Kondo H, et al.. European Journal of Applied Physiology, 2011.Read the paper ↗PubMed ↗Source 3 · Clinical trialEffects of repeated local heat therapy on skeletal muscle structure and function in humansKim K, Reid BA, Casey CA, et al.. Journal of Applied Physiology, 2020.Read the paper ↗PubMed ↗Source 4 · Clinical trialSix weeks of localized heat therapy does not affect muscle mass, strength and contractile properties in healthy active humansLabidi M, Ihsan M, Behan FP, et al.. European Journal of Applied Physiology, 2021.Read the paper ↗PubMed ↗Source 5 · Clinical trialNo clear benefit of muscle heating on hypertrophy and strength with resistance trainingStadnyk AMJ, Rehrer NJ, Handcock PJ, et al.. Temperature, 2018.Read the paper ↗PubMed ↗ It slowed muscle loss in the one immobilization study.Source 1 · Clinical trialDaily heat treatment maintains mitochondrial function and attenuates atrophy in human skeletal muscle subjected to immobilizationHafen PS, Abbott K, Bowden J, et al.. Journal of Applied Physiology, 2019.Read the paper ↗PubMed ↗

  3. MagnitudeDoes the claim match the size of the effect?

    16/25

    The claim promises muscle built and kept. Heat trimmed 10-day shrinkage from 7.6% to 4.5% in immobilized legs, and the sauna trial found no extra growth.Source 1 · Clinical trialDaily heat treatment maintains mitochondrial function and attenuates atrophy in human skeletal muscle subjected to immobilizationHafen PS, Abbott K, Bowden J, et al.. Journal of Applied Physiology, 2019.Read the paper ↗PubMed ↗Source 6 · Clinical trialEffects of repeated use of post-exercise infrared sauna on neuromuscular performance and muscle hypertrophyAhokas EK, Hanstock HG, Kyröläinen H, et al.. Frontiers in Sports and Active Living, 2025.Read the paper ↗PubMed ↗

  4. DoseDoes the studied dose match how people use it?

    16/25

    The positive results came from heating one muscle for 90 minutes to 8 hours a day.Source 3 · Clinical trialEffects of repeated local heat therapy on skeletal muscle structure and function in humansKim K, Reid BA, Casey CA, et al.. Journal of Applied Physiology, 2020.Read the paper ↗PubMed ↗Source 2 · Clinical trialResponses of muscle mass, strength and gene transcripts to long-term heat stress in healthy human subjectsGoto K, Oda H, Kondo H, et al.. European Journal of Applied Physiology, 2011.Read the paper ↗PubMed ↗Source 1 · Clinical trialDaily heat treatment maintains mitochondrial function and attenuates atrophy in human skeletal muscle subjected to immobilizationHafen PS, Abbott K, Bowden J, et al.. Journal of Applied Physiology, 2019.Read the paper ↗PubMed ↗ A sauna warms muscle less. Forty minutes at 80°C raised muscle temperature 1.95°C, against 4.2°C with diathermy.Source 10 · Clinical trialThe vascular response to acute sauna heating is similar in young and middle-aged adultsLeach OK, Strong K, Mack GW, et al.. Journal of Applied Physiology, 2024.Read the paper ↗PubMed ↗Source 1 · Clinical trialDaily heat treatment maintains mitochondrial function and attenuates atrophy in human skeletal muscle subjected to immobilizationHafen PS, Abbott K, Bowden J, et al.. Journal of Applied Physiology, 2019.Read the paper ↗PubMed ↗

The claim drifts from the data here

The helpful human results came from heating one muscle directly for hours a day. A sauna heats the whole body for minutes, and 40 minutes at 80°C warmed muscle by 1.95°C in one study.Source 10 · Clinical trialThe vascular response to acute sauna heating is similar in young and middle-aged adultsLeach OK, Strong K, Mack GW, et al.. Journal of Applied Physiology, 2024.Read the paper ↗PubMed ↗

Wellness sites offer the growth hormone rise as the mechanism. The famous 16-fold rise came from two hour-long saunas a day, and researchers never followed it through to muscle gains.Source 11 · Clinical trialEndocrine effects of repeated sauna bathingLeppäluoto J, Huttunen P, Hirvonen J, et al.. Acta Physiologica Scandinavica, 1986.Read the paper ↗PubMed ↗

A sauna with no workout can leave you weaker for a day. After a 70°C session, maximal leg force was still 4.1% lower 24 hours later.Source 12 · Clinical trialAcute Neuromuscular and Hormonal Responses to Different Exercise Loadings Followed by a SaunaRissanen JA, Häkkinen A, Laukkanen J, et al.. Journal of Strength and Conditioning Research, 2020.Read the paper ↗PubMed ↗

Put it to use

Let training build the muscle, and add a post-workout sauna if you like it. In the one trial of that routine, athletes gained as much muscle as those who skipped the heat.Source 6 · Clinical trialEffects of repeated use of post-exercise infrared sauna on neuromuscular performance and muscle hypertrophyAhokas EK, Hanstock HG, Kyröläinen H, et al.. Frontiers in Sports and Active Living, 2025.Read the paper ↗PubMed ↗

From our sister magazine

Sauna Monthly compares infrared cabins and times the plunge around training

Sauna Monthly · Shop

Sauna Monthly compares infrared cabins on price and build

Some plug into a wall outlet and others need a hardwired circuit.

Read it on Sauna Monthly

Sauna Monthly · Guide

Time your plunge around your training

Keep a hard plunge a few hours away from heavy lifting.

Read it on Sauna Monthly

People also ask

Is sauna good for muscle growth?

It added no extra muscle in the one trial that tested it. Female athletes who took a 10-minute infrared sauna after training gained muscle at the same rate as matched athletes who skipped it.Source 6 · Clinical trialEffects of repeated use of post-exercise infrared sauna on neuromuscular performance and muscle hypertrophyAhokas EK, Hanstock HG, Kyröläinen H, et al.. Frontiers in Sports and Active Living, 2025.Read the paper ↗PubMed ↗ Local heating devices have given mixed results.Source 3 · Clinical trialEffects of repeated local heat therapy on skeletal muscle structure and function in humansKim K, Reid BA, Casey CA, et al.. Journal of Applied Physiology, 2020.Read the paper ↗PubMed ↗Source 4 · Clinical trialSix weeks of localized heat therapy does not affect muscle mass, strength and contractile properties in healthy active humansLabidi M, Ihsan M, Behan FP, et al.. European Journal of Applied Physiology, 2021.Read the paper ↗PubMed ↗

Can a sauna prevent muscle loss?

A sauna hasn't been tested for that. Deep heat aimed at one thigh for two hours a day slowed muscle loss during 10 days of immobilization, and the muscle shrank 4.5% with heat against 7.6% with a sham.Source 1 · Clinical trialDaily heat treatment maintains mitochondrial function and attenuates atrophy in human skeletal muscle subjected to immobilizationHafen PS, Abbott K, Bowden J, et al.. Journal of Applied Physiology, 2019.Read the paper ↗PubMed ↗

Should you use the sauna before or after lifting?

The studies favor after. A sauna alone lowered maximal strength, and leg force was still 4.1% lower a day later.Source 12 · Clinical trialAcute Neuromuscular and Hormonal Responses to Different Exercise Loadings Followed by a SaunaRissanen JA, Häkkinen A, Laukkanen J, et al.. Journal of Strength and Conditioning Research, 2020.Read the paper ↗PubMed ↗ Athletes who used an infrared sauna after training kept making gains.Source 6 · Clinical trialEffects of repeated use of post-exercise infrared sauna on neuromuscular performance and muscle hypertrophyAhokas EK, Hanstock HG, Kyröläinen H, et al.. Frontiers in Sports and Active Living, 2025.Read the paper ↗PubMed ↗

Check these claims next

60°H

Stretched

Heat

“A sauna session raises your growth hormone 16-fold.”

The 16-fold rise came from ten men doing two hour-long saunas a day for a week, and it faded after the third day. One ordinary session gives a small, brief bump in younger men and none in older men.

22°H

Likely

Cold

“Ice baths after lifting weights blunt your muscle gains.”

In several trials, people who got into cold water right after their strength sessions for weeks built less muscle and strength, and three pooled analyses point the same way. Most studies put only the legs into water at about 10°C for 10 to 20 minutes.

52°H

Unsettled

Heat

“A sauna after training boosts your endurance.”

Post-training saunas expand blood plasma and help athletes cope with heat, and six runners lasted 32% longer in a run to exhaustion. When 13 men tried training both with and without sauna in a randomized trial, the sauna added nothing to hemoglobin mass or aerobic fitness.

We cited these sources

  1. 01Hafen PS, Abbott K, Bowden J, Lopiano R, Hancock CR, Hyldahl RD. Daily heat treatment maintains mitochondrial function and attenuates atrophy in human skeletal muscle subjected to immobilization. Journal of Applied Physiology. 2019;127(1):47-57. doi:10.1152/japplphysiol.01098.2018 PMID 31046520
  2. 02Goto K, Oda H, Kondo H, Igaki M, Suzuki A, Tsuchiya S, et al.. Responses of muscle mass, strength and gene transcripts to long-term heat stress in healthy human subjects. European Journal of Applied Physiology. 2011;111(1):17-27. doi:10.1007/s00421-010-1617-1 PMID 20803152
  3. 03Kim K, Reid BA, Casey CA, Bender BE, Ro B, Song Q, et al.. Effects of repeated local heat therapy on skeletal muscle structure and function in humans. Journal of Applied Physiology. 2020;128(3):483-492. doi:10.1152/japplphysiol.00701.2019 PMID 31971474
  4. 04Labidi M, Ihsan M, Behan FP, Alhammoud M, Smith T, Mohamed M, et al.. Six weeks of localized heat therapy does not affect muscle mass, strength and contractile properties in healthy active humans. European Journal of Applied Physiology. 2021;121(2):573-582. doi:10.1007/s00421-020-04545-9 PMID 33159573
  5. 05Stadnyk AMJ, Rehrer NJ, Handcock PJ, Meredith-Jones KA, Cotter JD. No clear benefit of muscle heating on hypertrophy and strength with resistance training. Temperature. 2018;5(2):175-183. doi:10.1080/23328940.2017.1391366 PMID 30393753
  6. 06Ahokas EK, Hanstock HG, Kyröläinen H, Ihalainen JK. Effects of repeated use of post-exercise infrared sauna on neuromuscular performance and muscle hypertrophy. Frontiers in Sports and Active Living. 2025;7:1462901. doi:10.3389/fspor.2025.1462901 PMID 40104529
  7. 07Piccolo DD, Corbett J, Exell TA, Moore JM, Wright A, Alnajjar MGA, et al.. Effect of repeated hot water immersion on muscle strength, power, function and physical activity in healthy older adults: A randomised crossover trial. Experimental Physiology. 2026:EP093501. doi:10.1113/EP093501 PMID 42010888
  8. 08Naito H, Powers SK, Demirel HA, Sugiura T, Dodd SL, Aoki J. Heat stress attenuates skeletal muscle atrophy in hindlimb-unweighted rats. Journal of Applied Physiology. 2000;88(1):359-363. doi:10.1152/jappl.2000.88.1.359 PMID 10642402
  9. 09Rodrigues P, Trajano GS, Wharton L, Minett GM. Effects of passive heating intervention on muscle hypertrophy and neuromuscular function: A preliminary systematic review with meta-analysis. Journal of Thermal Biology. 2020;93:102684. doi:10.1016/j.jtherbio.2020.102684 PMID 33077110
  10. 10Leach OK, Strong K, Mack GW, Gifford JR. The vascular response to acute sauna heating is similar in young and middle-aged adults. Journal of Applied Physiology. 2024;136(3):573-582. doi:10.1152/japplphysiol.00287.2023 PMID 38271083
  11. 11Leppäluoto 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. doi:10.1111/j.1748-1716.1986.tb08000.x PMID 3788622
  12. 12Rissanen JA, Häkkinen A, Laukkanen J, Kraemer WJ, Häkkinen K. Acute Neuromuscular and Hormonal Responses to Different Exercise Loadings Followed by a Sauna. Journal of Strength and Conditioning Research. 2020;34(2):313-322. doi:10.1519/JSC.0000000000003371 PMID 31490429