Cold Training: Ice Bath, Cold Shower and Winter Swimming – Effects, Getting Started and Safety

Why everyone is suddenly jumping into cold water

Ice barrels on balconies, plunge pools in every gym, New Year's swims in the lake: cold training has gone from niche hobby to trend. The promises are big – more energy, a stronger immune system, faster recovery, fat burning, better mood. Some of it is well supported, some plausible but unproven, and some simply marketing.

This article sorts out what research actually shows, what a sensible start looks like and which rules you should never break. Because for all the enthusiasm: cold water is one of the few training stimuli that can become life-threatening within minutes if you make mistakes.

The four forms at a glance

The decisive difference is not just the temperature but how much skin is in the cold water at once. In the shower, the water only ever hits part of the body; when you submerge, it surrounds almost everything at once, and water draws heat from the body many times faster than air. In winter swimming, open water, currents and the distance to the shore come on top.

What happens in the body

The first one to three minutes in cold water belong to the cold shock: an involuntary deep breath, then fast, barely controllable breathing, a jump in heart rate and blood pressure. The blood vessels of the skin constrict and blood shifts to the trunk. The body releases stress hormones – above all noradrenaline. In a frequently cited study by Šrámek et al. (2000), noradrenaline rose by around 530 % after an hour in 14 °C water. That explains the feeling of alertness and clarity almost everyone describes after cold water.

With repetition the body adapts: after a few weeks the cold shock is measurably weaker, and breathing settles faster. This habituation is the best-supported effect of cold training – and at the same time a safety gain if you ever fall into cold water unintentionally.

What research shows – and what it doesn't

Well supported

• Habituation to the cold shock. Even a few short sessions weaken the breathing and circulation response. This has been well studied for decades, including in the work of Mike Tipton, for example in the review article "Cold water immersion: kill or cure?" (2017).
• Less muscle soreness after hard exercise – a little. A meta-analysis by Machado et al. (2016) found a small to moderate effect on muscle soreness, most likely at 11–15 °C and 11–15 minutes. Noticeable, but no miracle cure.
• Dampened muscle growth when the cold comes right after strength training. In the study by Roberts et al. (2015) muscle mass and strength grew less over twelve weeks when participants went into cold water after every session than with active recovery. The inflammatory response that cold dampens is also a signal for adaptation.

Plausible, but thinly supported

• Fewer sick days from cold showers. In the large randomised study by Buijze et al. (2016) with around 3,000 participants, people who took cold showers of 30 to 90 seconds for 30 days called in sick about 29 % less often. The number of days of illness itself did not differ, though. Participants stayed home less often but did not fall ill less often – an effect on wellbeing, not on the immune system.
• Mood and stress. Many winter swimmers report a better mood, and there are case reports on depression. Controlled studies are small and short; whether it is the cold, the exercise outdoors or the community that works is open.
• Brown fat and metabolism. Cold activates brown fat, which produces heat – that is well supported. That a few minutes of ice bath a week therefore help noticeably with weight loss is not.

Not supported so far

"Boosts the immune system", "heals inflammation", "burns fat" – for these promises in their general form there is no solid data. A review by Espeland et al. (2022) sums up the situation soberly: many studies are small, many participants are experienced winter swimmers, and whether cold is the cause of the observed differences usually cannot be said. The frequently cited study on the Wim Hof method also tested a combination of breathing, cold and meditation – not cold alone.

Getting started: six weeks of cold showers

Start with the cold shower, not the ice barrel. It is safe, costs nothing and trains exactly what matters at the beginning: keeping your breathing calm during the cold shock.

1. Weeks 1–2: Shower warm, 30 seconds cold at the end. Legs and arms first, then the upper body.
2. Weeks 3–4: 60 seconds cold, now chest, back and neck from the start as well.
3. Weeks 5–6: 90 seconds to 2 minutes. If you like, start cold right away instead of warm.

The rule for every step: only move on once you can breathe out calmly and slowly again within about 30 seconds after the first shock. You don't need more than two to three minutes under the cold shower in everyday life.

After that you can move on to the cold plunge or ice bath – first the cool plunge pool at 10–15 °C, then the ice bath around 5 °C, each for 30 to 60 seconds, not straight to ice water and five minutes. Never increase time and cold at the same time. Winter swimming is the last step and belongs exclusively in an experienced group.

When cold fits into your training

• Building muscle is the goal: No cold directly after strength training. With a few hours' gap or on rest days it is unproblematic.
• Endurance or tournaments with several efforts close together: Here a cold bath between sessions can help you feel fresher.
• Simply for the mind: In the morning under the cold shower the timing doesn't matter – as long as you warm up afterwards.

More on the role of cold in recovery – and why sleep beats every ice bath – is in the article Sleep and recovery.

Safety: the rules you never break

This article is not medical advice. Cold is a strong stimulus for the heart and circulation, and most serious incidents do not happen through freezing but through the cold shock in the first minute.

• Check with a doctor first if you have cardiovascular disease, heart rhythm disorders, high blood pressure, Raynaud's syndrome, cold urticaria, epilepsy and during pregnancy.
• Never alone in the ice bath, the barrel or open water. A second person must be able to see you and help in an emergency.
• No alcohol – neither before nor afterwards to "warm up". It dilates the vessels, speeds up cooling and clouds judgement.
• No breathing exercises and no breath-holding in the water. Hyperventilation before immersion or diving in cold water can lead to sudden loss of consciousness. Breathing techniques belong on land.
• Get in slowly, never head first. No jumping into the plunge pool, least of all after the sauna.
• Get out at the first warning signs: uncontrollable shivering, numb or clumsy hands, dizziness, slowed thinking, pain.
• Warm up slowly: Dry off, dry warm clothes, a hat, a warm drink, light movement. Core temperature keeps dropping for a few minutes after you get out – not straight under the hot shower or into the sauna.

Tracking cold in Movepath

Movepath has the new category Cold for this with four exercises: Cold shower, Ice bath, Cold plunge and Winter swimming. You log them like plank or stretching as a duration – only the time in cold water, not preparation and warming up. That way you see in the analysis how your cold minutes develop over weeks, can set yourself a goal and collect XP like with any other exercise.

Progression in particular benefits from a log: 30 seconds in week one, two minutes in week six – in black and white, instead of estimated from memory. And if you had no desire for cold water for a week, you'll see that too.

Conclusion

Cold training is not a cure-all, but an honest, well-dosable stimulus: it wakes you up, you demonstrably get used to the cold shock, and many people feel better afterwards. For broader health promises the evidence is missing – and for building muscle, cold directly after training is even counterproductive. Anyone who starts with 30 seconds of cold shower, builds up slowly and takes the safety rules seriously can try it at low risk and find out for themselves what it does for them.