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Cold water swimming and training: what is known, and what is a myth

CrossFit Wilanów

Winter swimming is something of a Polish national sport: from November to March you will see people walking into lakes and rivers in nothing but a swimsuit and a woolly hat. Some people at our box do it, and some of them ask whether it helps their training. Below is what can be said about cold water reliably, and what is not worth promising.

What cold water swimming is, and how cold “cold” is

Cold water swimming means getting into cold water: a lake, a river, the sea or a tub. Researchers do not have one strict definition of “cold water”. A 2020 review (Knechtle and colleagues) takes it to mean water below 15 °C. Ice swimming, the competitive version, is in water colder than 5 °C. For comparison, the thermoneutral temperature for a person in water, where the body does not lose heat, is about 35 °C.

The authors point out that the body’s responses are strongest at 10-15 °C, water many people would call “just chilly”. The cold does not have to be extreme to be serious.

The first minutes: cold shock

The first reaction to getting into cold water is the cold shock response. Breathing becomes rapid and hard to control, and the heart rate rises. The review describes this response as strongest in roughly the first 30 seconds and fading within about two minutes, with the “shock” phase covering about the first three minutes. That is the riskiest moment, and according to the authors most deaths from immersion in cold water happen then.

A few practical points follow:

  • Get in slowly and try to breathe calmly.
  • Go with an experienced person the first time. The review recommends supervision and gradual acclimatisation, and beginners are a group at particular risk.
  • Do not drink alcohol beforehand. According to the review, alcohol speeds up cooling.
  • If you have a heart condition, or are not sure whether you can do it, ask your doctor. The authors write that people with known or undiagnosed heart disease have a higher risk of heart rhythm problems in cold water.

Preparing for the first time

Preparation is practical. What to bring:

  • a swimsuit,
  • water shoes (the bottom can be slippery or hard),
  • a hat and gloves for when you come out,
  • a mat or rug to change on, so you are not standing on cold ground,
  • a towel,
  • a warm drink in a flask.

How long you stay in depends on the water temperature and your experience. Start with short dips and lengthen them gradually. You can warm up lightly before getting in, for example with ten or fifteen minutes of jogging. Get dressed as soon as you are out.

Cold water after training: here is the catch

Many people get into cold water after training because they believe it speeds up recovery. The evidence is mixed.

A Cochrane systematic review (Bleakley and colleagues, 2012) covered 17 small studies with 366 participants in total. It found that after immersion in cold water (below 15 °C) participants reported less muscle soreness than people who simply rested, but the authors rated the quality of the studies as low.

The second point matters more if you care about strength. In the study by Roberts and colleagues (2015), 21 active men did strength training twice a week for 12 weeks. After each session some of them spent 10 minutes in cold water, and the rest did active recovery. Strength and muscle mass increased more in the active-recovery group. In the second part of the study, cold water after exercise blunted the signals linked to muscle growth. The authors wrote that using cold water as a regular post-exercise recovery method is worth reconsidering.

What this means for you:

  • If the main goal of your training is strength or muscle mass, do not get into cold water straight after strength training. The study does not say how long to wait, so the simplest approach is to swim on rest days or well after training.
  • If you do it for enjoyment rather than for recovery from training, this applies to you less.
  • The study had 21 people and one specific protocol, so do not treat it as final proof. But it is reason enough not to promise that cold water after training always helps.

What else the research says

The review by Tipton and colleagues (2017) assesses the whole field of cold water: alongside the dangers it discusses the claimed benefits. The authors write that the strength of evidence differs between claims, and some are still, as they put it, anecdotal speculation. The Knechtle review adds that cold water swimming appears to bring health benefits when practised by experienced, healthy people, regularly and gradually, and that for beginners the risk is real.

So we do not write that cold water swimming improves sleep, immunity or mood. Many people say it does, but we will not state it as fact, because we have not gathered that evidence here.

Where to do it

Ideally somewhere you can get into the water with other people, with an easy way in and a place to change, and with someone who will react if something goes wrong.

The club does not organise regular group swims, and that is deliberate. It works like this: every season a few members swim more or less regularly and post in the club’s Facebook group that at the weekend they are heading to Jeziorko Czerniakowskie or to Wawa Wake, and invite the rest. Whoever wants to joins. These are meet-ups between members, not club sessions, so the rules in this piece, especially about the first time and about heart conditions, apply to everyone at their own risk.

The one place where cold water is part of the programme is the camp at FITstodoła: there is a sauna and a cold plunge tub, so during the camp we do contrast therapy, alternating heat and cold. There, someone is watching, and that is exactly the condition described above.

Sources

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