Cold switches on brown fat
In 24 healthy men scanned in mild cold air at 16 C, brown fat activity appeared in 23 of them and not at 22 C, and was lower in heavier men. Cold air in a scanner, not a plunge.
Cold plunge and cold water · what it helps, and what it costs
What cold plunges have actually been measured to do
Cold water after a hard session makes muscles less sore the next day, and that is the best-pooled result on the page. Cold water after strength training also blunts the strength the training was for, and that is the best-pooled harm. The wellbeing and metabolism claims rest on thinner ground.
25 sources, each resolved on PubMed or read at the regulator or society that published it. None of the 6 goals meets the rule for a stronger record, which is printed below. 4 are thin, null, or ahead of the marketing. Learning only. No clinic, device or brand is named.
Plate 44
Cold record
What a study immersed
25
Sources on the page
6
Goals in people
On this page. Counts, not a grade and not a ranking.
No goal on this page meets the rule for a stronger record. The rule is printed above the goals, and the count it read is printed under each one.
Read this first
Educational use only. This page is not medical advice. Water temperatures and durations are what a study ran, not a setting for you. Cold water can trigger gasping, an abnormal heart rhythm and drowning, and is a question for your own clinician if you have heart disease or high blood pressure. Aaron Cuha is a coach, not a doctor.
Educational use only. This database summarizes published research and is not medical advice. Where a dose appears it is a record of what a trial or clinic ran, or what people describe doing, with its source attached. Nothing here is a recommendation for personal use.
What it is
A cold plunge is immersion in cold water, usually to the neck, for seconds to minutes. In the research it is called cold-water immersion, and the 2025 health meta-analysis defined it as water at 15 C or colder for at least 30 seconds. Ice baths, cold showers and winter swimming are versions of it.
Most cold water research is sports recovery: athletes immersed after a hard session, measured the next day. A separate line of research uses days of mild cold air to study brown fat and blood sugar, and is often cited for plunges although it did not use water.
The cold shock response is the first minute: a gasp, fast breathing and a racing heart. It is the reason the safety section is first-class here, and the reason the research distinguishes a first plunge from a habitual one.
How it is thought to work
The proposed stories are that cold dampens inflammation after exercise, switches on brown fat, and trains the stress response. Some of that is measured in people. The inflammation story in particular was tested inside muscle and did not hold up. This section says which is which.
Cold acclimation and blood sugar
In 8 people with type 2 diabetes, 10 days of cold at 14 to 15 C raised insulin sensitivity about 43 percent, mostly through muscle rather than brown fat. Uncontrolled, and in cold air.
The cold shock response habituates
Across 17 groups, the gasp and racing heart of cold immersion shrank with repetition after about 4 immersions, with heart rate 14 beats a minute lower. The authors suggest this could lower drowning risk.
Where the mechanism story is weak
It blunted strength training
In 21 active men over 12 weeks, 10 minutes of cold water after each strength session gave smaller gains in strength and muscle than active recovery, and type II fibres grew only without the cold.
It did not dampen inflammation in muscle
In nine men with muscle biopsies after leg exercise, 10 minutes at 10 C produced the same inflammation and cell stress inside the muscle as easy cycling.
Some claims are anecdote
A broad review of cold water as hazard and treatment concluded that the evidence for its claims varies and some remains at the level of anecdotal speculation.
The dose words, and what a trial ran
Every number here is what a study ran, named beside it. None is a setting for a reader. Water and air cool the body at very different rates, so a 15 C bath and a 15 C room are not the same exposure.
- Water temperature
- The health meta-analysis included 7 to 15 C. The soreness meta-analysis found 10 to 15 C gave the best results; the strength trials used 10 and 15 C.
- Duration
- From 30 seconds to 2 hours in the health meta-analysis. The soreness meta-analysis found 10 to 15 minutes best. The cold shower trial used 30, 60 or 90 seconds.
- Timing
- Right after a strength session is the timing that blunted gains. The soreness benefit was measured 24 hours after a hard session.
- Cold air acclimation
- A different exposure: hours a day in a cool room at 14 to 16 C, or cold enough to shiver for 1 hour a day, for 10 days. It is where the brown fat and blood sugar results come from.
What a trial ran
Each row is a record from a paper. It is not a plan for you.
| Goal | Who | What the trial ran | Source |
|---|---|---|---|
| Strength training | 21 active men | 12 weeks of strength training twice a week, with 10 minutes of cold water or active recovery after each session. | PMID 26174323 |
| Muscle inflammation | Nine active men, crossover | Lower body in 10 C water for 10 minutes after leg exercise, against 10 minutes of easy cycling. | PMID 27704555 |
| Hormones after lifting | 11 strength-trained men, crossover | 15 minutes at 15 C after back squats, against passive rest. | PMID 31222379 |
| Sick days | 3018 working adults | 30, 60 or 90 seconds of cold at the end of a hot shower for 30 days, against a usual shower. | PMID 27631616 |
| Blood sugar, type 2 diabetes | 8 people with type 2 diabetes | 10 days of cold acclimation at 14 to 15 C. | PMID 26147760 |
| Blood sugar, overweight | 15 adults with overweight or obesity | Cold enough to shiver for 1 hour a day for 10 days. | PMID 39643644 |
What studies in people found, by goal
Stronger records first. Nulls and marketing-ahead goals stay on the same page. Every card is people only; animal work is in its own section below. Nothing here is ranked against the others, and no clinic or device is recommended.
How the tier is decided, so you can check it against the counts printed under each one. Stronger: a clinical guideline or a medical society's indication list recommends it in a named setting, or a pooled analysis of randomised trials favours cold water and the source rated the certainty moderate. Thin: the pooled result was null or went against cold water for the goal as named, the source rated it very low, or nothing was pooled at all. Mixed: everything else, including a result that moved one measure and not another.
Mixed, local, or early
52 studies pooled; certainty not graded by the source; result favours cold water
Soreness and recovery after hard exercise. Less soreness the next day is the best-pooled result for cold water
Who was studied
Physically active people after one hard session. A 2022 meta-analysis pooled 52 studies against passive rest, a 2023 one 28 studies against other recovery methods, and a 2016 one nine randomised trials. One author of the 2022 and 2023 analyses holds a football club grant to study cold water recovery.
Against passive rest, soreness 24 hours after high-intensity exercise improved (SMD -0.89), perceived recovery improved, and muscular power recovered slightly better. Against other methods, cold water was better for soreness and similar for power; air cryotherapy was better for strength recovery. 10 to 15 C for 10 to 15 minutes did best in the 2016 analysis.
Setting in the evidence
Immersion in 10 to 15 C water after exercise, mostly in sport settings.
What this does not show
Better fitness over weeks. Recovering faster from one session is a different question from adapting to many, which is the next card.
- Review of studiesImpact of Cold-Water Immersion Compared with Passive Recovery Following a Single Bout of Strenuous Exercise on Athletic Performance in Physically Active Participants: A Systematic Review with Meta-analysis and Meta-regression (2022)
- Review of studiesEffects of Cold-Water Immersion Compared with Other Recovery Modalities on Athletic Performance Following Acute Strenuous Exercise in Physically Active Participants: A Systematic Review, Meta-Analysis, and Meta-Regression (2023)
- Review of studiesCan Water Temperature and Immersion Time Influence the Effect of Cold Water Immersion on Muscle Soreness? A Systematic Review and Meta-Analysis (2016)
Mixed, local, or early
11 randomised trials pooled, 3,177 people; certainty not graded by the source; result mixed
Stress, sleep, mood and sick days. Lower stress at one time point and fewer sick days off work; mood and immune measures did not move
Who was studied
Healthy adults in a 2025 meta-analysis of 11 randomised trials and 3177 people. Most of those people are from one trial, 3018 Dutch adults finishing a hot shower with 30 to 90 seconds of cold for 30 days, one of whose authors worked for an insurer during the study.
Inflammation rose right after cold (SMD 1.03) and at 1 hour (1.26). Stress was lower at 12 hours (SMD -1.00) but not immediately, at 1 hour, 24 hours or 48 hours. Immune measures did not change. Sleep quality and quality of life improved narratively, and mood did not. In the shower trial, sickness absence was 29 percent lower, but days of illness did not differ.
Setting in the evidence
Cold baths at 7 to 15 C and cold showers.
What this does not show
Fewer infections. The shower trial counted days off work, not days ill, and people knew which group they were in.
Thin, null, or marketing ahead
10 studies pooled, 170 people; certainty not graded by the source; result went against cold water
Strength and muscle from training. Cold water after lifting blunted the strength gains it was meant to help
Who was studied
People strength training for weeks with or without cold water after each session. A 2023 meta-analysis of 10 studies and 170 people, 92 percent men; a 2021 meta-analysis of eight articles; and the 12-week trial in 21 men with muscle biopsies.
The 2023 analysis found smaller strength gains with cold water (effect size -0.23), more so when only the trained limbs were cooled (-0.31); whole-body immersion did not differ significantly. The 2021 analysis found smaller gains in maximal strength and strength endurance (SMD -0.60). In the trial, muscle fibres grew only without the cold. After squats, cold blunted the rise in testosterone and IL-6.
Setting in the evidence
Cold water at 10 to 15 C straight after strength training.
What this does not show
Harm from cold at other times of day. These studies put the cold right after the strength session.
- Review of studiesEffects of post-exercise cold-water immersion on resistance training-induced gains in muscular strength: a meta-analysis (2023)
- Review of studiesThe Effects of Regular Cold-Water Immersion Use on Training-Induced Changes in Strength and Endurance Performance: A Systematic Review with Meta-Analysis (2021)
- Study in peoplePost-exercise cold water immersion attenuates acute anabolic signalling and long-term adaptations in muscle to strength training (2015)
- Study in peopleCold-water immersion blunts and delays increases in circulating testosterone and cytokines post-resistance exercise (2019)
Thin, null, or marketing ahead
studies pooled, count not printed in the abstract; certainty not graded by the source; result null
Endurance from training. Regular cold water neither helped nor hurt endurance gains
Who was studied
Endurance training studies pooled in the 2021 meta-analysis, which included eight articles across strength and endurance.
With endurance training, regular cold water had no effect on time-trial power, maximal aerobic power in a graded test or time-trial duration.
Setting in the evidence
Cold water at 15 C or colder alongside a training programme.
What this does not show
A benefit for endurance athletes. The pooled result was null.
Thin, null, or marketing ahead
nothing pooled; certainty not graded by the source; no pooled result
Brown fat, blood sugar and weight. Days of cold air changed brown fat and blood sugar in small uncontrolled studies; plunges were not tested
Who was studied
24 men in a scanner at 16 C; 8 people with type 2 diabetes and 10 obese men after 10 days of mild cold; 15 adults with overweight after 10 days of shivering; young winter swimmers against controls; and two identical twins, one of them the Iceman. Two authors of the winter swimmer study work with obesity drug companies.
Brown fat activity appeared in 23 of 24 men in cold. Insulin sensitivity rose about 43 percent in the diabetes group, and glucose tolerance, triglycerides and blood pressure improved after shivering. Winter swimmers produced more heat in cold. The Iceman and his brother, who does not practise cold, had comparable brown fat activity.
Setting in the evidence
Mild cold air at 14 to 16 C for hours, or shivering for 1 hour a day.
What this does not show
Weight loss, or any effect of a plunge of a few minutes. These are days of cold air, mostly without a control group.
- Study in peopleCold-activated brown adipose tissue in healthy men (2009)
- Study in peopleShort-term cold acclimation improves insulin sensitivity in patients with type 2 diabetes mellitus (2015)
- Study in peopleShort-term Cold Acclimation Recruits Brown Adipose Tissue in Obese Humans (2016)
- Study in peopleCold acclimation with shivering improves metabolic health in adults with overweight or obesity (2024)
- Study in peopleAltered brown fat thermoregulation and enhanced cold-induced thermogenesis in young, healthy, winter-swimming men (2021)
- Study in peopleFrequent extreme cold exposure and brown fat and cold-induced thermogenesis: a study in a monozygotic twin (2014)
Thin, null, or marketing ahead
nothing pooled; certainty not graded by the source; no pooled result
Longevity and ageing. No study in the search measured ageing or lifespan in people who plunge
Who was studied
Nobody, for this goal. The closest is a broad review of cold water as hazard and treatment.
The review found the evidence for cold water's claims varies and some remains anecdotal speculation. The mouse work on hearts and arteries is in the animal section.
Setting in the evidence
Not applicable.
What this does not show
Any lifespan or ageing benefit in people.
What studies in animals found, kept apart
Animal studies give cold a metabolism and heart story, and one result that runs the other way: rats that were not used to cold gained fat when cooled. They are here, apart from the people.
Mice, acute cold
Brown fat switched between burning fat and glucose depending on feeding, and the liver's glucose production was critical for heat production during fasting.
Obese mice, cold
Cold resolved obesity-related inflammation and insulin resistance through a brown fat lipid, maresin 2. Two authors hold a pending patent on it.
Obese rats raised warm
Rats raised warm, to suppress brown fat as in humans, gained weight and 125 percent more fat under the skin when moved to a cooler room.
Mice, 30 days of cold
Cold-kept mice developed less artery calcification than mice at room temperature.
Mice, chronic cold
Hearts grew 2 to 3 times as much as with exercise, reversed on rewarming, and resembled exercise growth rather than disease.
How to read this record
Recovery and adaptation are different goals with opposite answers. Cold water after a hard session reduces next-day soreness. Cold water after strength training, repeated for weeks, reduced the strength gains in two meta-analyses and a 12-week trial.
The inflammation story behind the soreness result did not hold inside muscle: biopsies showed the same inflammation after cold water as after easy cycling.
The wellbeing evidence is a meta-analysis whose people mostly come from one cold shower trial that counted days off work. Stress was lower at one time point out of five, and mood did not change.
The brown fat and blood sugar results are from days of mild cold air in small groups, mostly without controls. They are often quoted for plunges of a few minutes, which they did not test.
A position, labelled as one
The blocks above are the studies. The block below is a judgment about what to do with them. It has to say where it goes past the measurements.
Aaron Cuha’s position
This is opinion, not a finding. Everything else on this page is the evidence.
A cold plunge after a hard session reduces next-day soreness, and repeated after strength training it blunts the strength gains. Claims for mood, immunity, metabolism and longevity run ahead of the trials, and the immediate risk, the cold shock response, is real and documented.
The reasoning
- 52 studies pooled against passive rest found less soreness 24 hours after high-intensity exercise.
- Two meta-analyses and a 12-week biopsy trial found smaller strength gains with cold water after lifting.
- In the wellbeing meta-analysis, stress fell at one of five time points, mood did not change, and most people came from one shower trial.
- The metabolic results come from days of cold air, not plunges, in groups of 8 to 24.
Where this goes beyond the evidence
This position goes beyond the evidence in treating the wellbeing results as weak: a large trial of habitual plunging measuring mood and infections properly has not been run, and could show a real effect. It also generalises the strength result from studies where cold came straight after lifting; cold at another time of day has barely been tested and may not blunt anything. If such trials show otherwise, this position is too cautious.
Who this is not for
Anyone with heart disease, an abnormal heart rhythm or uncontrolled blood pressure who has not asked their own clinician; anyone plunging alone or in open water without help nearby; anyone breath holding in cold water; and anyone who wants this page to replace a clinician or a coach.
Aaron Cuha, who built this archive and reads the studies behind the pages. He is a coach, not a doctor, and no medical credential is claimed for him anywhere on this site. More about who writes this
Who it is for, and who it is wrong for
For
- Someone who plunges after strength training and wants to know what two meta-analyses found about the gains.
- Someone who has seen cold water sold for mood, immunity and fat loss and wants the trial record before buying a tub.
Wrong for
Anyone lifting for strength or size
Cold water straight after strength sessions reduced strength gains in two meta-analyses, and muscle fibres grew only without it in a 12-week trial.
Anyone with a heart condition
Cold water submersion can trigger abnormal heart rhythms in healthy volunteers, and the combination of cold shock and breath holding is proposed as a cause of sudden death.
Anyone alone in open water
The cold shock response causes gasping and hyperventilation in the first minute, and is linked to drowning and to unexplained whitewater deaths.
Anyone wanting a personal protocol
Temperatures and durations here are records of what a study ran. They are not instructions for your body.
Limits and safety, with the numbers
Cold shock
The cold shock response induces hyperventilation, raises the risk of abnormal heart rhythm and increases drowning risk. It habituated with repeated immersion, after about 4 immersions, across 17 groups.
Heart rhythm
Cold water submersion can induce abnormal heart rhythms in healthy volunteers. The cold shock and diving responses, triggered together by submersion with a held breath, are proposed to explain some deaths blamed on drowning.
Open water
Sudden unexplained deaths in cold whitewater, called flush drownings, may be explained by cold water immersion syndrome, according to a 2019 review.
Training adaptation
Cold water straight after strength sessions reduced strength gains and, in a crossover, blunted the testosterone and IL-6 response to squats.
Where this sits in the archive
This site teaches a blood panel, protein and training before gadgets. Cold water does not move that order, and for strength training the evidence says it can cost some of what the training builds.
Disclosed both ways: the owner of this archive lists the cold plunge in his own protocol at /my-protocols. That is a personal choice recorded there, not a finding on this page.
Nothing on this page is for sale. No seller wrote it, and no tub, chiller or brand is named or ranked.
Setups, not a shopping list
Four ways cold is sold. No brand is named, and none is ranked.
Plunge tub or ice bath
Immersion to the chest or neck in cold water, usually for minutes.
Evidence match. The recovery and strength studies, mostly at 10 to 15 C.
Mismatch. The brown fat and blood sugar results were not from tubs.
Cold shower
Cold water at the end of a hot shower, for seconds.
Evidence match. The 3018-person Dutch trial, 30 to 90 seconds.
Mismatch. It counted days off work, not days ill, and did not test mood or metabolism.
Winter or open-water swimming
Swimming in cold natural water, often paired with a sauna.
Evidence match. The winter swimmer brown fat study, cross-sectional.
Mismatch. Open water adds drowning risk; the comparison groups chose their own habits.
Cold air acclimation
Hours a day in a cool room, or cold enough to shiver.
Evidence match. The brown fat, insulin sensitivity and shivering studies.
Mismatch. Not a plunge, and small uncontrolled groups.
What a cold habit has to state before it can be compared with a study
- The water temperature and duration actually used. The soreness benefit was best at 10 to 15 C for 10 to 15 minutes.
- When it sits relative to training: straight after strength work is the timing that blunted gains.
- Whether the goal is next-day recovery, long-term adaptation, wellbeing or metabolism, because those have different answers.
- Who is nearby and whether there is breath holding. The documented deaths involve cold shock, open water and held breath.
Claims this page will not make
- Cold plunges reduce inflammation.
- Inflammation rose right after cold in the 2025 meta-analysis, and inside muscle after exercise cold water matched easy cycling.
- Cold plunges speed recovery.
- Next-day soreness was lower in pooled studies. That is recovery from one session, not better fitness.
- Cold plunges build muscle.
- Cold water after lifting reduced strength gains in two meta-analyses and muscle fibre growth in a 12-week trial.
- Cold plunges boost immunity.
- Immune measures did not change in the 2025 meta-analysis. The cold shower trial found fewer days off work, not fewer days ill.
- Cold plunges burn fat.
- Brown fat activates in cold air. No study in the search found weight loss from plunges, and rats not used to cold gained fat when cooled.
- Cold plunges improve mood.
- Mood did not improve in the 2025 meta-analysis; stress was lower at 12 hours only.
Related doors
Floor habits and the neighbouring pages. None of these is a cart.
Neighbour
Sauna and heat
The opposite stress, held to the same rule.
Neighbour
Wim Hof breathing
The method that pairs cold with breath holds.
Floor
Training and muscle
What cold water after lifting costs the training.
Floor
Start from a blood panel
A marker, or a panel you still need. Not a diagnosis.
Disclosure
The owner's own protocol
Where the cold plunge appears in a personal plan, labelled as one.
Order
What this teaches
Measure first. Floor habits before gadgets.
Map
The longevity protocol
Every pillar, this one among them, held to the same rule.
Questions people ask
- Should a cold plunge come before or after lifting?
- This page does not set a protocol. What the studies found is that cold water straight after strength sessions reduced strength gains, and that cold at other times has barely been tested.
- Does a cold plunge help recovery?
- It reduced soreness 24 hours after a hard session across 52 pooled studies. That is not the same as getting fitter.
- Does cold water boost brown fat?
- Mild cold air for days increased brown fat activity in small studies. Plunges of a few minutes were not what they tested.
- Is a cold shower the same as a plunge?
- No. The large shower trial used 30 to 90 seconds at the end of a hot shower and measured days off work.
- What is the main risk?
- The cold shock response in the first minute: gasping, fast breathing and a racing heart, linked to abnormal heart rhythm and drowning. It lessens with repeated exposure.
- Is this a cold plunge protocol?
- No. Aaron is a coach, not a doctor, and this page reports what studies ran. It does not set a temperature, a duration or a schedule for anyone.
Sources
Knowledge stays free. No seller wrote this page. Every source below opens the record that was checked before the sentence was written, with what it found and who funded it.
- N Engl J Med, 2009. Cold-activated brown adipose tissue in healthy men Study in people
24 healthy men, 10 lean and 14 overweight or obese, scanned at 22 C and at a mild 16 C. Brown fat activity appeared in 23 of 24 during cold, not at the warmer temperature, and was lower in the heavier men. Cold air, not water. No funding or conflict statement in the PubMed record.
- Nat Med, 2015. Short-term cold acclimation improves insulin sensitivity in patients with type 2 diabetes mellitus Study in people
8 people with type 2 diabetes, 10 days of cold acclimation at 14 to 15 C. Peripheral insulin sensitivity rose about 43 percent, mostly through muscle glucose transport, with only a minor rise in brown fat glucose uptake. Uncontrolled, and cold air. PubMed tags it as non-government funded; no conflict statement in the record.
- J Therm Biol, 2024. Habituation of the cold shock response: A systematic review and meta-analysis Review of studies
17 groups. The cold shock response (gasping, fast breathing, a racing heart) habituated with repeated immersion, after about 4 immersions: heart rate fell 14 beats a minute and minute ventilation 21.3 litres a minute. No conflicts declared.
- J Physiol, 2015. Post-exercise cold water immersion attenuates acute anabolic signalling and long-term adaptations in muscle to strength training Study in people
21 active men, 12 weeks of strength training twice a week with 10 minutes of cold water or active recovery after each session. Strength and muscle mass rose more with active recovery; type II fibre size rose 17 percent only in that group. A second study of nine men found blunted satellite cell and growth signalling after cold. PubMed tags it as non-government funded; no conflict statement in the record.
- J Physiol, 2017. The effects of cold water immersion and active recovery on inflammation and cell stress responses in human skeletal muscle after resistance exercise Study in people
Nine active men, lower body in 10 C water for 10 minutes or 10 minutes of easy cycling after leg exercise, with muscle biopsies to 48 hours. Inflammation and stress responses inside the muscle did not differ. PubMed tags it as non-government funded; no conflict statement in the record.
- Exp Physiol, 2017. Cold water immersion: kill or cure? Review of studies
Review across the field of cold water as hazard and treatment, from drowning, cardiac arrest and hypothermia to inflammation. The evidence for the claims varies, and some remains at the level of anecdotal speculation. No funding or conflict statement in the PubMed record.
- Eur J Appl Physiol, 2019. Cold-water immersion blunts and delays increases in circulating testosterone and cytokines post-resistance exercise Study in people
11 strength-trained men, 15 minutes at 15 C or passive rest after back squats, crossover. Free testosterone at 60 minutes fell 10.4 percent below baseline after cold and not after rest; the IL-6 rise at 30 minutes was 4.9 against 47.5 percent. Funded by the University of Rhode Island.
- PLoS One, 2016. The Effect of Cold Showering on Health and Work: A Randomized Controlled Trial Study in people
3018 Dutch adults randomised to 30, 60 or 90 seconds of cold at the end of a hot shower, or a usual shower, for 30 days. Sickness absence from work was 29 percent lower (rate ratio 0.71); days of illness did not differ. Declared interest: one author was employed by an insurer, Achmea, during the study. No funding statement in the PubMed record.
- Nat Metab, 2024. Cold acclimation with shivering improves metabolic health in adults with overweight or obesity Study in people
15 men and postmenopausal women with overweight or obesity, cold enough to shiver for 1 hour a day for 10 days. Oral glucose tolerance, fasting glucose, triglycerides and blood pressure improved. No control group in the abstract. Funded by the Dutch Diabetes Research Foundation and ZonMw; no conflicts declared.
- Sports Med, 2022. Impact of Cold-Water Immersion Compared with Passive Recovery Following a Single Bout of Strenuous Exercise on Athletic Performance in Physically Active Participants: A Systematic Review with Meta-analysis and Meta-regression Review of studies
52 studies in physically active people. Against passive rest, cold water improved muscle soreness 24 hours after high-intensity exercise (SMD -0.89), perceived recovery (0.66) and recovery of muscular power (0.34 after eccentric exercise). One author holds a grant from a football club to study cold water recovery; the others declare no conflicts.
- Sports Med, 2023. Effects of Cold-Water Immersion Compared with Other Recovery Modalities on Athletic Performance Following Acute Strenuous Exercise in Physically Active Participants: A Systematic Review, Meta-Analysis, and Meta-Regression Review of studies
28 studies. Cold water beat other recovery methods for soreness and matched them for power and flexibility; air cryotherapy beat cold water for strength recovery. Water temperature and duration rarely changed the result. No conflict statement in the PubMed record.
- Sports Med, 2016. Can Water Temperature and Immersion Time Influence the Effect of Cold Water Immersion on Muscle Soreness? A Systematic Review and Meta-Analysis Review of studies
Nine randomised trials against passive recovery. Cold water was slightly better for soreness; 10 to 15 C and 10 to 15 minutes gave the best results. Funded by Brazilian state and national research agencies; no conflicts declared.
- Eur J Sport Sci, 2023. Effects of post-exercise cold-water immersion on resistance training-induced gains in muscular strength: a meta-analysis Review of studies
10 studies, 170 people, 92 percent men. Cold water after strength sessions reduced strength gains (effect size -0.23); applied to the trained limbs only, -0.31; whole-body immersion showed no significant difference (-0.08). No conflict statement in the PubMed record.
- Sports Med, 2021. The Effects of Regular Cold-Water Immersion Use on Training-Induced Changes in Strength and Endurance Performance: A Systematic Review with Meta-Analysis Review of studies
Eight articles. With strength training, regular cold water reduced gains in one-repetition maximum, isometric strength and strength endurance (SMD -0.60) and ballistic power (-0.61). With endurance training it had no effect on time trials or maximal aerobic power. Funded by the Sao Paulo state research foundation.
- PLoS One, 2025. Effects of cold-water immersion on health and wellbeing: A systematic review and meta-analysis Review of studies
11 randomised trials, 3177 healthy adults, water at 7 to 15 C for 30 seconds to 2 hours. Inflammation rose immediately and at 1 hour (SMD 1.03 and 1.26); stress was lower at 12 hours (SMD -1.00) but not at any other time point; immune measures did not change. Narratively, sleep quality and quality of life improved, mood did not. No competing interests declared.
- Diabetes, 2016. Short-term Cold Acclimation Recruits Brown Adipose Tissue in Obese Humans Study in people
10 metabolically healthy obese men, 10 days of mild cold. Cold-induced glucose uptake in brown fat rose; white fat glucose uptake did not change. PubMed tags it as non-government funded; no conflict statement in the record.
- Cell Rep Med, 2021. Altered brown fat thermoregulation and enhanced cold-induced thermogenesis in young, healthy, winter-swimming men Study in people
Young men who swim in winter and use a sauna 2 to 3 times a week, against controls. The swimmers had lower core temperature and a greater rise in heat production in cold, while brown fat glucose uptake rose similarly in both. Cross-sectional. Declared interests: one author consults for Novo Nordisk; another works for an obesity drug company.
- PLoS One, 2014. Frequent extreme cold exposure and brown fat and cold-induced thermogenesis: a study in a monozygotic twin Study in people
Two people: the Dutchman known as the Iceman and his identical twin brother, who does not practise cold exposure. Brown fat activity was comparable (1144 and 1325), and cold-induced heat production was 40.1 and 41.9 percent, with both using a breathing technique. No competing interests declared.
- Cell Metab, 2023. Comprehensive quantification of metabolic flux during acute cold stress in mice Animal study
Mice, acute cold. Brown fat burned fat when fasted and glucose when fed; liver glucose production was critical for heat production during fasting. Funded by the NIH heart and diabetes institutes; no competing interests declared.
- Nat Metab, 2022. Brown adipose tissue-derived MaR2 contributes to cold-induced resolution of inflammation Animal study
Diet-induced obese mice. Cold resolved obesity-related inflammation and insulin resistance, through a brown fat lipid mediator, maresin 2. Two authors are inventors on a pending patent on maresin 2 for metabolic therapy. Funded by the NIH heart and diabetes institutes.
- Int J Mol Sci, 2022. Cold Exposure Drives Weight Gain and Adiposity following Chronic Suppression of Brown Adipose Tissue Animal study
Obese rats raised warm to suppress brown fat, as in humans, then moved from 28 to 20 C. They gained weight and 125 percent more fat under the skin. Funded by the British Heart Foundation; no conflicts declared.
- J Nanobiotechnology, 2023. Cold exposure protects against medial arterial calcification development via autophagy Animal study
Mice kept cold for 30 days developed less vitamin D-induced artery calcification than mice at room temperature, through exosomes that promoted autophagy. Funded by Chinese national and provincial science grants; no competing interests declared.
- J Exp Biol, 2024. Chronic cold exposure causes left ventricular hypertrophy that appears to be physiological Animal study
Mice under chronic cold grew larger hearts, 2 to 3 times the growth typically seen with exercise, which reversed on rewarming and resembled exercise growth rather than disease. Funded by the American Heart Association, Illumina and the NIH; no competing interests declared.
- J Physiol, 2012. 'Autonomic conflict': a different way to die during cold water immersion? Review of studies
Review. Cold water submersion can induce cardiac arrhythmias in healthy volunteers. The authors propose that the cold shock response and the diving response, triggered together by submersion and breath holding, may explain some deaths wrongly attributed to drowning. No funding or conflict statement in the PubMed record.
- Wilderness Environ Med, 2019. Cold Water Immersion Syndrome and Whitewater Recreation Fatalities Review of studies
Review of sudden unexplained deaths in cold whitewater, which the authors suggest cold water immersion syndrome may explain. No funding or conflict statement in the PubMed record.
Educational use only. This page is not medical advice. Water temperatures and durations are what a study ran, not a setting for you. Cold water can trigger gasping, an abnormal heart rhythm and drowning, and is a question for your own clinician if you have heart disease or high blood pressure. Aaron Cuha is a coach, not a doctor.
Educational use only. This database summarizes published research and is not medical advice. Where a dose appears it is a record of what a trial or clinic ran, or what people describe doing, with its source attached. Nothing here is a recommendation for personal use.