Cold water and ice baths: what the evidence really says

What cold water does do

Getting into cold water lowers skin and muscle temperature and narrows blood vessels near the surface. That tends to dull pain signals and reduce the feeling of heat and swelling in hard-worked muscles, which is where the reduction in perceived soreness comes from.

• Short-term relief: people usually feel less sore for a while afterwards, and sometimes the next day.
• A sense of freshness: many people feel alert and energised after a cold dip, and that is a real and pleasant effect, even if it is hard to measure.
• Back-to-back performance: when you have to perform again within 24 hours or so, such as a two-day tournament or a competition with heats, feeling fresher may be worth more than long-term adaptation.
• Cooling after hot sessions: after training or racing in heat, cold water is an effective way to bring body temperature down.

Plenty of people also enjoy the ritual and the mental challenge of it. That is a perfectly good reason to do something, as long as you are clear that it is enjoyment rather than a proven performance tool.

It is worth separating cold water immersion from cold showers. A cold shower cools the body far less than sitting in cold water up to your chest, so most research findings do not transfer directly. Cold showers are a fine way to wake yourself up, but think of them as a lifestyle choice rather than a recovery protocol.

The catch for strength and muscle

Here is the part the trend tends to skip. Some research suggests that regularly getting into cold water straight after strength training can reduce gains in muscle size and strength over a training block. The likely reason is that the inflammation and blood flow changes after a session are part of the signal that tells your body to adapt. Blunt them every time and you may blunt the adaptation a little too.

The effect seems modest and the research is not settled, but if building muscle or strength is your goal, it is a sensible reason not to make an ice bath a post-lifting habit. For more on what actually drives muscle growth, see our guide to how to build muscle.

If you want to try it

Start gently. There is no evidence that colder and longer is better, and plenty of reasons to think it is riskier.

1. Begin with 30 to 60 seconds of cold water at the end of a normal shower for a week or two.
2. If you move to a bath or plunge, most research protocols use water somewhere around 10 to 15°C for a few minutes up to about 10 to 15 minutes. You do not need ice-cold water.
3. Enter slowly and breathe out steadily. Do not hold your breath or duck your head under.
4. Get out if you start shivering hard, lose feeling in your hands or feet, or feel unwell.
5. Warm up gradually with dry clothes, a warm drink and some easy movement.

Consider the cost as well. Home plunge tubs and chillers are expensive, and spas and clubs charge per session. If money is tight, spending it on good food, decent trainers or coaching will do more for your recovery and results than a plunge tub will.

Who should avoid it or check first

Sudden immersion in cold water triggers a cold shock response: a reflex gasp, fast breathing and a spike in heart rate and blood pressure. It peaks in the first minute. In open water, that gasp can lead to inhaling water, and it is a known factor in drownings around UK lakes, rivers and coastline, which stay cold even in summer.

• Never do open water dips alone, and never jump straight in.
• Speak to your GP first if you have a heart condition, high blood pressure, or have ever fainted during exercise.
• Avoid it if you have Raynaud's, cold urticaria or poor circulation.
• If you are pregnant, check with your midwife or GP before starting.
• Do not use cold water after drinking alcohol.

For a fresh injury such as a sprained ankle, the question of whether to use cold is a separate one, covered in our guide to heat or ice for injuries.

Where it fits for HYROX and hybrid athletes

After a HYROX race, your legs, grip and lungs have all taken a beating. A cold dip may make the next day feel a bit easier, and there is no adaptation to protect straight after a race, so it is a reasonable choice if you like it. It is not necessary. Sleep, food, fluids and a couple of easy days do the heavy lifting. Our guide to recovering after HYROX sets out the full picture.

During a training block, the priorities are the same as for any lifter: get the sessions done, sleep well and eat enough. At Lycan Strength, members preparing for a race build strength in the Full Body, Upper and Lower classes and conditioning in Engine and Lycan Shred, and the gains from that training come from consistency, not from the plunge afterwards. If you are curious about heat as well as cold, our guide to sauna and recovery covers the other side of the temperature debate.