Cold plunge

The short version

I use a cold plunge. The cleanest finding is a hormone one: an hour in 57°F (14°C) water raised norepinephrine 530% and dopamine 250% in young men.¹
The mood evidence is encouraging but thin: 33 adults felt more positive after 5 minutes at about 68°F (20°C), with no control group.²
The most solid result is a warning: regular cold-water immersion after strength training blunts strength and muscle gains.^3,4
Immune claims are split. A 3,018-person cold-shower trial cut sickness absence 29% but did not change illness days.⁵
Rhonda Patrick, PhD, uses a cold plunge herself and has a specific view on dose and timing, covered below.⁶

The protocol

This is what the research used, not a prescription and not a record of my own routine.

Parameter	What the research used	Source
Hormone response	1 hour head-out at 14°C (57°F) raised norepinephrine 530% and dopamine 250%; at 20°C (68°F) the metabolic rate rose 93%	¹
Mood	One 5-minute immersion to the clavicles at about 20°C (68°F)	²
Frequency, observed	Winter swimmers averaged about 2.6 swims a week, 11 minutes a week in cold water in total, which is what that group did, not a recommended dose	⁷
Showers	A 30-, 60-, or 90-second cold finish to a hot shower, daily for 30 days	⁵
Acclimation	10 days at 14 to 15°C (57 to 59°F) in people with type 2 diabetes	⁸
Strength training	10 minutes of cold immersion after each session cost strength and muscle gains	⁴
Patrick's stated dose	About 50°F (10°C) for 2 minutes, which she says raises norepinephrine about twofold	⁶

Why it works

Cold is a sympathetic nervous system event. In the one-hour experiment, the authors concluded the cold effects mainly reflect sympathetic activation, and the metabolic rate rose 350% at 14°C (57°F).¹

Humans also carry brown fat that burns energy in the cold. In 24 healthy men, brown fat was active in 23 of them at 16°C (61°F) but not at 22°C (72°F), and it was lower in overweight or obese men.⁹

A review of the field treats cold water as a stress that can be a threat or a treatment depending on circumstance, which is the right frame for everything below.¹⁰

What the research says

Early Cold raises catecholamines. Young men sitting head-out for an hour at 14°C (57°F) saw norepinephrine up 530%, dopamine up 250%, and metabolic rate up 350%, while adrenaline did not change.¹ That is an hour of cold and a small physiology experiment, so it tells me about hormones, not focus or mood in daily life.¹

Early Brown fat and metabolism. Ten days of cold acclimation at 14 to 15°C (57 to 59°F) raised insulin sensitivity about 43% in eight people with type 2 diabetes.⁸ The abstract does not say whether that was cold air or water, so I do not read it as plunge guidance.⁸ Winter swimmers (7 men versus 8 controls) showed larger cold-induced increases in thermogenesis, but the authors say causality cannot be concluded.⁷

Early Mood. In 33 healthy adults, positive affect rose by a mean of 7 points on the PANAS scale (p < 0.001) and negative affect fell by 4.66 (p = 0.005) after a 5-minute immersion at about 20°C (68°F).² There was no control group and no randomization, so the lift could come from the challenge itself.²

Moderate Soreness. A Cochrane review of 17 small, low-quality trials (366 participants) found less soreness than passive recovery at 24 hours (standardized mean difference -0.55, 95% CI -0.84 to -0.27), 48 hours (-0.66), 72 hours (-0.93), and 96 hours (-0.58).¹¹

Strong Strength and muscle growth are worse with regular cold after lifting. A meta-analysis of 8 articles found harm to strength outcomes (standardized mean difference -0.60; 95% CI -0.87 to -0.33) and ballistic performance (-0.61), but no effect on aerobic power or time trials with endurance training.³ In a 12-week trial of 21 men, 10 minutes of cold immersion after training led to smaller gains than active recovery, with type II fiber area up 17% for active recovery and not for cold.⁴ These are small trials in young active men, but the direction is consistent.^3,4

Mixed Immunity. In 3,018 adults randomized to 30, 60, or 90 seconds of cold at the end of a hot shower for 30 days, sickness absence from work fell 29% (incidence rate ratio 0.71, P = 0.003), but illness days did not differ.⁵ People know when they have taken a cold shower, so the self-reported absence could partly reflect expectation.⁵

Rhonda Patrick on cold exposure

I looked for the foundmyfitness.com topic and episode pages, but the site would not load for me, so this section rests on the publisher's feed, her January 2026 talk (read as an auto-generated transcript on a mirror), and a few other pages. I list what I could open.⁶

In the 2026 talk she describes herself using a cold plunge and calls about 50°F (10°C) for 2 minutes her favorite protocol, for a norepinephrine boost she links to focus, attention, and mood.⁶ She also names about 20 seconds at 35°F (2°C) as producing a similar twofold norepinephrine rise, and about 15 minutes at 50°F for mitochondrial effects.⁶ She says she prefers cold-water immersion over cryotherapy, and describes a small sham-controlled cryotherapy study in depression.⁶

Her view on lifting matches the data above: she advises against deliberate cold around resistance training if the goal is muscle, and suggests recovery days, endurance days, or many hours away from the weights.⁶ A chapter title from a 2025 FoundMyFitness episode makes the same contrast, heat supports resistance training "unlike cold."¹²

Earlier work: a 2016 solo episode frames cold shock as hormesis and compares cryotherapy with cold-water immersion.¹³ In her 2017 interview with Jari Laukkanen, a chapter covers adding cold-water immersion to the sauna.¹⁴ Her 2022 MedCram episode has segments on cold therapy and hydration after sauna.¹⁵

What I could not verify: the studies behind her 2-minute and 20-second claims. Her one-hour, about 57°F reference appears to match the experiment I cite above.^6,1 I also did not find her cold safety guidance in the pages I could open. These are her words about research and her own body, not an endorsement of anything I do.

Sauna and cold together

I use both. The evidence on the pairing is mostly about what happens in people who do both, not what the combination adds.

In the winter-swimmer comparison, the swimmers did cold dips alternated with sauna, and the group averaged 11 minutes of cold and 57 minutes of sauna heat a week; with 7 swimmers and no way to separate the two, it cannot say what the pairing does.⁷ Alternating hot and cold water after exercise beat passive recovery for soreness and strength loss in a meta-analysis of 18 trials, though all had a high risk of bias and the baths were hot water, not sauna.¹⁶

I found no trial comparing sauna-then-cold with cold-then-sauna, so ordering is a judgment call, not a finding. The solid piece is the lifting result: cold after strength work costs gains.^3,4 So the cold, not the sauna, is the thing to keep away from heavy lifting. That is a reading of the evidence, not a trial result. Patrick's advice in the 2026 talk points the same direction.⁶

How I use it

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

Cautions

Cold shock is the real danger. Cold water immersion is linked to drowning, cardiac arrest, and hypothermia.¹⁰
One proposed mechanism is "autonomic conflict": the cold shock response (racing heart) and the diving response (slowing heart) fire together and can trigger rhythm problems, especially in people with predisposing conditions.¹⁷ That is a hypothesis from a review with no incidence figures, so I take it as a reason for respect, not a probability.¹⁷
Regular cold after lifting blunts strength and muscle gains.^3,4
Several of the benefits above come from trials of a few people, and the mood and immune findings could be expectation.^2,5
I found no data on going straight from a hot sauna into cold water, so the cautions on each stand on their own and I would not assume the combination is safe.
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

Šrámek P, Simečková M, Janský L, Savlíková J, Vybíral S. Human physiological responses to immersion into water of different temperatures. European Journal of Applied Physiology. 2000;81(5):436-442.Lab or mechanistic studyPubMed 10751106 · DOI
What it found: Young men sat head-out in water for 1 hour at 32°C, 20°C, and 14°C (90°F, 68°F, 57°F). At 14°C metabolic rate rose 350%, norepinephrine 530%, and dopamine 250%, while adrenaline did not change; the authors attribute the cold effects mainly to sympathetic activation.
Limits: A small physiology experiment in young men (the abstract does not give the number) showing hormone responses during one hour in the water, not a trial of any health outcome.
Yankouskaya A, Williamson R, Stacey C, Totman JJ, Massey H. Short-Term Head-Out Whole-Body Cold-Water Immersion Facilitates Positive Affect and Increases Interaction between Large-Scale Brain Networks. Biology. 2023;12(2):211.Lab or mechanistic studyPubMed 36829490 · DOI
What it found: fMRI study of 33 healthy adults aged 20 to 45 scanned before and after 5 minutes of head-out immersion in water at about 20°C (68°F). Positive affect rose (mean difference 7 points on the PANAS scale, p < 0.001) and negative affect fell (-4.66, p = 0.005), alongside changes in brain network connectivity.
Limits: Before-and-after design with no control group and no randomization, so the mood lift could come from the challenge itself, and it measures a single immersion.
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.
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.
Buijze GA, Sierevelt IN, van der Heijden BCJM, Dijkgraaf MG, Frings-Dresen MHW. The Effect of Cold Showering on Health and Work: A Randomized Controlled Trial. PLoS ONE. 2016;11(9):e0161749.Randomized trialPubMed 27631616 · DOI
What it found: Randomized trial of 3,018 Dutch adults aged 18 to 65 assigned to a 30-, 60-, or 90-second cold finish to a hot shower for 30 days, or to a control group. Sickness absence from work fell 29% (incidence rate ratio 0.71, P = 0.003), but the number of illness days did not differ between groups.
Limits: Participants know whether they take cold showers, so the self-reported sickness absence could reflect expectation or motivation, and only 79% completed the 30-day protocol.
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.
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.
Hanssen MJW, Hoeks J, Brans B, van der Lans AAJJ, Schaart G, van den Driessche JJ, et al. Short-term cold acclimation improves insulin sensitivity in patients with type 2 diabetes mellitus. Nature Medicine. 2015;21(8):863-865.Lab or mechanistic studyPubMed 26147760 · DOI
What it found: Ten days of cold acclimation at 14 to 15°C (57 to 59°F) raised peripheral insulin sensitivity by about 43% in eight people with type 2 diabetes, alongside a marked rise in muscle GLUT4 translocation. Brown fat glucose uptake rose only slightly.
Limits: Eight patients, no control group, and the abstract does not say whether the exposure was cold air or cold water, so it is not a cold plunge protocol.
van Marken Lichtenbelt WD, Vanhommerig JW, Smulders NM, Drossaerts JM, Kemerink GJ, Bouvy ND, et al. Cold-activated brown adipose tissue in healthy men. The New England Journal of Medicine. 2009;360(15):1500-1508.Cross-sectional studyPubMed 19357405 · DOI
What it found: PET/CT study of 24 healthy men (10 lean, 14 overweight or obese) at 22°C and in mild cold at 16°C. Brown fat activity appeared in 23 of 24 men in the cold but not at the warmer temperature, and was lower in overweight or obese men than in lean men (P = 0.007).
Limits: A snapshot of 24 men that shows brown fat exists and responds to cold, not that cold exposure changes body weight or health.
Tipton MJ, Collier N, Massey H, Corbett J, Harper M. Cold water immersion: kill or cure?. Experimental Physiology. 2017;102(11):1335-1355.ReviewPubMed 28833689 · DOI
What it found: Review of the threats and uses of cold water immersion, from drowning, cardiac arrest, and hypothermia to treating hyperthermia and managing inflammation. The authors rate the evidence behind each claim and conclude that some uses have a credible rationale while others remain anecdotal.
Limits: A narrative review whose abstract gives no numbers, so it frames risk and benefit but does not quantify either.
Bleakley C, McDonough S, Gardner E, Baxter GD, Hopkins JT, Davison GW. Cold-water immersion (cryotherapy) for preventing and treating muscle soreness after exercise. The Cochrane Database of Systematic Reviews. 2012;2012(2):CD008262.Systematic reviewPubMed 22336838 · DOI
What it found: Cochrane review of 17 small trials (366 participants, all rated low quality) of cold-water immersion below 15°C after exercise. Versus passive recovery, soreness was lower at 24 hours (standardized mean difference -0.55; 95% CI -0.84 to -0.27), 48 hours (-0.66), 72 hours (-0.93), and 96 hours (-0.58).
Limits: Small, low-quality trials with heterogeneous results, most of which did not track adverse events, and it predates the strength-training findings that cold can blunt adaptation.
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.
Patrick R. #021 How Cryotherapy Affects the Brain, the Immune System, Metabolism, and Athletic Performance. FoundMyFitness, February 12, 2016.PodcastListen
What it found: A solo episode that frames cold shock as hormesis and walks through cold exposure and the brain, inflammation, thermogenesis, and whole-body cryotherapy versus cold water immersion.
Limits: I read only the show-note entry in the publisher's feed, which gives no doses, and it is a 2016 episode.
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.
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.
Shattock MJ, Tipton MJ. 'Autonomic conflict': a different way to die during cold water immersion?. The Journal of Physiology. 2012;590(14):3219-3230.ReviewPubMed 22547634 · DOI
What it found: Review proposing that cold water immersion can trigger heart rhythm problems when the cold shock response (sympathetic racing heart) and the diving response (parasympathetic slowing) fire at the same time. The authors suggest this 'autonomic conflict' may explain some deaths attributed to drowning or hypothermia, especially in people with predisposing conditions.
Limits: A hypothesis-driven review with no incidence numbers, so it explains a plausible mechanism rather than how often it happens.