Cold Therapy: Cryotherapy and Ice Baths

From wheelie bins filled with ice at rugby clubs to minus-110-degree cryo chambers in city-centre studios, cold exposure has become one of the most visible recovery rituals in sport. Yet the research tells a more complicated story than social media does: cold can ease soreness, but it may also blunt some of the adaptations you train for. Our editorial team weighed up the trials.

Types of cold therapy

"Cold therapy" is an umbrella term covering quite different practices. Cold-water immersion (CWI), commonly called an ice bath, involves sitting in water typically between about 10 and 15 °C up to the waist or chest for several minutes. Because water conducts heat far more efficiently than air, it cools tissues quickly even at temperatures that are not especially extreme.

Whole-body cryotherapy (WBC) uses chambers filled with very cold, dry air, often below −100 °C, for two to four minutes. Partial-body cryotherapy is a variant in which the head stays outside a cabin cooled with nitrogen vapour. Despite the dramatic temperatures, the brief exposure and the insulating effect of air mean that deep muscle cooling can be smaller than with a well-run ice bath.

Then there are local methods: ice packs, cold sprays and cooling compression devices, which have a long history in treating acute injuries. Finally, open-water or "wild" swimming in British lakes and seas has grown hugely in popularity, though it is usually pursued for wellbeing rather than structured recovery.

These methods should not be lumped together. Their physiology, cost and risk profiles differ, and so does the quality of evidence behind each one.

What happens in the body

Cold exposure triggers peripheral vasoconstriction: blood vessels in the skin and limbs narrow to preserve core temperature. Proponents argue that this reduces swelling and the movement of inflammatory cells into damaged muscle. Cold also slows nerve conduction, which partly explains its pain-relieving effect.

Immersion in water adds hydrostatic pressure, which may help shift fluid from the limbs back towards the centre of the body. Some researchers think part of the benefit of CWI comes from this pressure rather than the cold itself, which is why thermoneutral water immersion is sometimes used as a comparison in studies.

The initial seconds of sudden cold produce the "cold shock response": a gasp reflex, rapid breathing and a spike in heart rate and blood pressure. As Tipton and colleagues have described, this response is responsible for many cold-water drownings and is the main acute hazard of plunging into very cold water.

At the molecular level, cooling muscle after resistance exercise appears to dampen some signalling pathways linked to protein synthesis and satellite cell activity. Peake and colleagues (2017) found that cold-water immersion did not reduce intramuscular inflammation more than active recovery after a resistance session, challenging a long-held assumption.

Soreness and short-term recovery

The best-summarised outcome is delayed-onset muscle soreness (DOMS). A Cochrane review by Bleakley and colleagues (2012) concluded that cold-water immersion may reduce soreness in the days after exercise compared with passive rest, although the trials were small and of variable quality. Effects on objective measures of muscle function were less clear.

A later meta-analysis by Machado and colleagues (2016) suggested that water temperatures of roughly 11–15 °C and immersion times of about 11–15 minutes were associated with the most consistent reductions in soreness. Colder is not necessarily better; very low temperatures add discomfort and risk without clear extra benefit.

For whole-body cryotherapy, a Cochrane review by Costello and colleagues (2015) found insufficient evidence to judge whether it reduces soreness or improves recovery compared with passive rest. Given its cost and the regulatory grey area many clinics operate in, this is an important finding.

In practical terms, CWI looks most useful when the next performance matters more than long-term adaptation: tournament days, multi-stage events, or fixture congestion in football and rugby where players compete twice within a few days.

The trade-off with strength and muscle gains

The turning point in this field was a study by Roberts and colleagues published in the Journal of Physiology in 2015. Over 12 weeks of strength training, participants who took a cold-water immersion after each session gained less muscle mass and strength than those who did active recovery. Biopsies showed reduced activation of anabolic signalling and satellite cells.

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Fyfe and colleagues (2019) reported a similar pattern: regular post-exercise cold immersion attenuated muscle fibre hypertrophy, although strength gains were less affected in their cohort. Together, these findings suggest that the inflammation and cellular stress cold suppresses are, at least partly, signals the body uses to adapt.

Endurance adaptations seem less clearly affected, and some studies even suggest cold may support certain mitochondrial responses. However, the data are mixed and too limited to draw firm conclusions.

The sensible conclusion is periodisation: use cold strategically during competition blocks and keep it away from sessions where adaptation is the main objective, especially in hypertrophy or strength phases.

Practical use and safety

If you decide to use cold immersion, a few principles from the literature and from sports medicine practice apply:

1. Aim for moderate temperatures (around 10–15 °C) rather than near-freezing water.
2. Keep exposures to roughly 5–15 minutes, depending on temperature and tolerance.
3. Enter slowly and control your breathing to blunt the cold shock response.
4. Never immerse alone in open water, and avoid immersing your head.
5. Separate immersion from strength sessions by several hours, or skip it during muscle-building phases.

Some people should be particularly cautious or avoid cold exposure altogether: those with heart disease, uncontrolled high blood pressure, Raynaud's phenomenon, cold urticaria, or a history of arrhythmia. The sudden rise in heart rate and blood pressure can be dangerous for them.

Whole-body cryotherapy has its own risks. Cold burns have occurred when skin was wet, when clothing was inadequate or when sessions exceeded recommended durations. Nitrogen-based cabins carry a risk of oxygen depletion if poorly ventilated. In the UK these services are not regulated as medical treatments, so choose operators who screen clients and supervise every session.

Open-water swimmers should also be aware of after-drop, the continued fall in core temperature after leaving the water, and of the risks of swimming in cold seas or reservoirs. Organised groups and qualified supervision greatly reduce these dangers.

Conclusions of the editorial team

Cold-water immersion can modestly reduce muscle soreness and is a reasonable tool when quick turnaround between competitions is the priority. Moderate temperatures and durations appear just as effective as extreme ones.

Used routinely after strength training, however, it may reduce the muscle growth you are working for. Timing and context matter more than the ritual itself.

Whole-body cryotherapy is expensive, and current evidence does not show it outperforms simpler options. Sleep, nutrition and sensible load management remain the foundations of recovery.

You may also find our editorial articles on sleep and recovery in athletes, heat acclimatisation and the role of protein timing after training useful.

References

1. Roberts LA, Raastad T, Markworth JF, 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):4285–4301.
2. Bleakley C, McDonough S, Gardner E, et al. Cold-water immersion (cryotherapy) for preventing and treating muscle soreness after exercise. Cochrane Database Syst Rev. 2012;(2):CD008262.
3. Costello JT, Baker PR, Minett GM, et al. Whole-body cryotherapy (extreme cold air exposure) for preventing and treating muscle soreness after exercise in adults. Cochrane Database Syst Rev. 2015;(9):CD010789.
4. Machado AF, Ferreira PH, Micheletti JK, et al. Can water temperature and immersion time influence the effect of cold water immersion on muscle soreness? A systematic review and meta-analysis. Sports Med. 2016;46(4):503–514.
5. Fyfe JJ, Broatch JR, Trewin AJ, et al. Cold water immersion attenuates anabolic signaling and skeletal muscle fiber hypertrophy, but not strength gain, following whole-body resistance training. J Appl Physiol. 2019;127(5):1403–1418.
6. Peake JM, Roberts LA, Figueiredo VC, et al. The effects of cold water immersion and active recovery on inflammation and cell stress responses in human skeletal muscle after resistance exercise. J Physiol. 2017;595(3):695–711.
7. Tipton MJ, Collier N, Massey H, et al. Cold water immersion: kill or cure? Exp Physiol. 2017;102(11):1335–1355.