Cold Showers and Ice Baths: What They Do, and Don't Do, for Testosterone

It is 6.15 on a February morning and he is standing next to a converted chest freezer in his garden. The water reads 3°C. He saw a video last month that promised cold plunges would raise his testosterone, sharpen his focus and melt his belly fat, and he has done it every day since, usually straight after his morning lifting session.

He does feel sharper afterwards. That part is real.

The testosterone part is not backed by any controlled human trial we could find. And the timing he has chosen, straight after lifting, is the one timing where the research suggests cold water may be working against him.

Where the testosterone claim comes from

The idea has two roots, and neither holds up the way it is usually told.

The first is the logic that testes work best cool, so cooling them must help. It is true that sperm production needs the testes to sit a few degrees below core body temperature, and that sustained heat harms it, as we explain in sperm count: what lowers it, what raises it. But avoiding heat damage is not the same as boosting hormone output with cold. There is no good evidence that brief cold exposure makes the testes produce more testosterone.

The second root is a striking set of numbers about brain chemicals. In a study by Šrámek and colleagues published in 2000, young men sat in water at different temperatures for an hour. At 14°C, plasma noradrenaline rose by 530 per cent and dopamine by 250 per cent, and metabolic rate rose by 350 per cent.

Those figures get quoted everywhere, usually attached to a two-minute plunge. Note what the study actually did: a full hour, head out, in 14°C water. It was not a study of testosterone, and it did not track how long the effect lasted after people got out.

We looked for a controlled human trial showing that regular cold showers or ice baths raise resting testosterone, and could not find one.

The part nobody mentions: cold after lifting

If you train for muscle, this is the most useful thing in this article.

In 2015, Roberts and colleagues ran a 12-week strength training study in 21 young men. After each session, one group sat in cold water at about 10°C for 10 minutes. The other did 10 minutes of easy cycling instead. By the end, the cold water group had gained less muscle and less strength than the active recovery group, and a separate part of the study found that cold water blunted the signalling inside the muscle that drives growth.

A 2019 study by Earp and colleagues looked at hormones directly. Eleven resistance-trained men did a heavy squat session twice, a week apart, followed either by 15 minutes of cold water immersion or by passive rest. Without cold water, testosterone was 9.2 per cent higher 30 minutes after the session. With cold water, it had barely moved, and by 60 minutes it was 10.4 per cent below where it started.

To keep that in proportion: the short-lived testosterone rise after lifting contributes very little to how much muscle you build, as we explain in does lifting increase testosterone. The Earp result matters less for its own sake than as a sign that cold water changes the recovery environment in the muscle. The Roberts result, less muscle and less strength after 12 weeks, is the one that should change what you do.

The simple fix

Separate them. If you enjoy cold water, do it on rest days, first thing in the morning before an evening session, or at least several hours after lifting. If you are an endurance athlete in a heavy competition block where the next session matters more than long-term muscle growth, cold water immediately after may still have a place. For someone training to build muscle, straight after the session is the worst time to do it.

What cold water does do

Stripped of the hormone claims, cold exposure has a small but real set of effects.

Alertness

The noradrenaline response is real, even if brief dips produce far less of it than an hour at 14°C. That jolt of alertness is the main reason people who do it daily say they feel better, and it is a legitimate reason to keep going if you like it.

Fewer sick days, not fewer illnesses

The biggest trial of cold showers, published in 2016 by Buijze and colleagues, randomised 3,018 working adults in the Netherlands to end their usual hot shower with 30, 60 or 90 seconds of cold water for 30 days, or to shower as normal.

The cold shower groups reported 29 per cent fewer days off sick from work. But the number of days they were ill did not change. The authors suggested people may have felt more able to work through minor illness, rather than getting ill less often. The length of the cold spell made no difference: 30 seconds did as well as 90.

Worth knowing: 79 per cent of those in the cold shower groups completed the 30 days, and the most common complaint was feeling cold for a while afterwards.

Brown fat

Cold activates brown adipose tissue, a type of fat that burns energy to produce heat. In a study by van Marken Lichtenbelt and colleagues, 24 healthy men were exposed to mild cold at 16°C, and brown fat activity appeared in 23 of them. Men with a higher BMI and more body fat had less of it.

That is interesting physiology, but it is not a fat-loss plan. The extra energy burned by occasional cold exposure is small compared with what diet and daily activity change. If belly fat is the goal, stubborn belly fat in men covers what actually moves it.

Cold water shock: the risk that is not a myth

Cold water deserves respect, and the danger is concentrated in the first minute.

The Royal Society for the Prevention of Accidents describes cold water shock as a response to sudden entry into water at 15°C or below. It triggers gasping and can make you breathe up to ten times faster than normal, along with a spike in heart rate and blood pressure that can cause a heart attack, even in people who are fit and healthy.

A few rules follow from that.

• Never do open-water cold swimming or plunging alone.
• Enter slowly rather than jumping or diving in, and let the gasping pass before you do anything else.
• Never combine cold water with breath-holding or with breathing techniques that involve deliberate hyperventilation. Hyperventilating before going under can cause you to black out without warning.
• Do not plunge after drinking alcohol.
• If you have a heart condition, high blood pressure or a history of fainting, talk to your doctor first.

A cold shower at the end of a warm one is far gentler than a plunge into a lake or an ice bath, and for most people it delivers much of the same alertness.

A note on saunas and hot tubs

Many people pair cold plunges with saunas. If fertility matters to you, the heat is the part to think about. In a small study, men who used a sauna twice a week for three months saw their sperm count and motility fall, and it took around six months after stopping for them to recover. That does not make saunas harmful for everyone. It does mean the contrast routine is not a fertility hack, whatever the videos say.

What to do instead, if testosterone is the goal

If you like cold water, keep doing it. It is cheap, it wakes you up, and if you time it away from lifting it is unlikely to do any harm. Just do not count it as part of your testosterone plan.

The things that measurably move testosterone are less dramatic. Sleep comes first: see the 90-minute sleep rule and does sleep affect testosterone. Body fat comes next. Then strength training done consistently, a sensible amount of daylight and vitamin D, and managing the kind of chronic stress described in cortisol spiking before lunch.

If you want to know where you actually stand, a testosterone test will tell you more than any morning routine.

Common questions

Do cold showers increase testosterone?

We could not find a controlled human trial showing that cold showers or ice baths raise resting testosterone. The claim relies on reasoning about testicular temperature and on brain chemical studies that did not measure it.

Should I take an ice bath after lifting weights?

Not if building muscle is the goal. In a 12-week study, men who used cold water after training gained less muscle and strength than men who did light cycling instead. Keep cold water several hours away from lifting.

How long should a cold shower be?

In the largest trial, 30 seconds of cold water at the end of a warm shower was as effective for the outcomes measured as 60 or 90 seconds.

Do ice baths burn fat?

Cold activates brown fat, which burns energy to make heat, but the amount is small compared with diet and activity. It is not a practical fat-loss tool on its own.

Is cold water immersion dangerous?

It can be. Sudden entry into water at 15°C or below triggers gasping, rapid breathing and a spike in heart rate and blood pressure. Never plunge alone in open water, never hold your breath under, and speak to a doctor first if you have heart problems.

Sources: Roberts LA et al., Post-exercise cold water immersion attenuates acute anabolic signalling and long-term adaptations in muscle to strength training, J Physiol 2015;593(18):4285-301 · Earp JE et al., Cold-water immersion blunts and delays increases in circulating testosterone and cytokines post-resistance exercise, Eur J Appl Physiol 2019;119(8):1901-7 · Šrámek P et al., Human physiological responses to immersion into water of different temperatures, Eur J Appl Physiol 2000;81(5):436-42 · Buijze GA et al., The effect of cold showering on health and work: a randomized controlled trial, PLoS One 2016;11(9):e0161749 · van Marken Lichtenbelt WD et al., Cold-activated brown adipose tissue in healthy men, N Engl J Med 2009;360(15):1500-8 · Garolla A et al., Seminal and molecular evidence that sauna exposure affects human spermatogenesis, Hum Reprod 2013;28(4):877-85 · Royal Society for the Prevention of Accidents, Cold water shock guidance · Educational only, not medical advice.

Keep reading: Does lifting increase testosterone? · Sperm count: what lowers it, what raises it · What testosterone does for muscle growth · Is cardio tanking your testosterone? · Sleep apnoea and testosterone · Does stress lower testosterone?