Ice baths are popular after a strenuous workoutWOJTEK RADWANSKI/AFP via Getty Images
Plunging into an ice bath after a workout may be worse for your muscle recovery than doing nothing. Cold therapy is a popular intervention after rigorous exercise, like marathons, to relieve soreness and dampen the inflammation that can impair muscle recovery. But in a new study, adults who had ice baths after intense leg exercise showed markers of muscle damage for longer than those who just rested.
“Ice baths have long been considered a go-to recovery strategy in sport, so many people might expect them to outperform doing nothing,” says Freya Bayne at the University of East London. But emerging studies suggest that cold therapies slow muscle-protein synthesis by restricting blood flow and reducing the supply of nutrients to the muscles. “The [latest] study contributes to a growing conversation that recovery strategies should be selected based on the desired outcome, rather than assuming one approach works for everything,” she says.
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The use of cold therapy – from ice baths and cold showers to open-water swimming – dates back centuries. Some studies suggest that cold therapy, particularly if it involves open-water swimming, benefits our mental health. But other claims, such as those made by Wim Hof around ice baths improving athletic performance and immune health, lack good scientific evidence.
Focusing on muscle recovery and soreness, Bayne and her colleagues compared cold therapy with other post-exercise interventions.
Forty adults who regularly strength-train had the strength of their quadriceps measured via a machine that also controls movement. While seated, the participants pushed against the machine as hard as possible while it kept their knee in a fixed position. They then performed a high-intensity knee-extension exercise using the same leg. This involved them trying to straighten their knee as much as possible while the machine pushed it back towards a bent position, causing the quadriceps to lengthen.
Similar movements occur when lowering into a squat or running downhill. These can cause small tears to muscle fibres, which trigger an inflammatory response and lead to muscle soreness. This discomfort usually kicks in within hours of doing a new or particularly intense workout, peaking between 24 and 72 hours, and fading after a week.
Straight after exercising, the participants’ muscle strength was measured again, revealing a loss of 36 per cent, on average. They were then randomly assigned to one of four recovery strategies: cold-water immersion at 9°C (48°F) for 15 minutes, hot-water immersion at 42°C (108°F) for 30 minutes, hot-air exposure at 30°C (86°F) for 30 minutes, or passive rest at room temperature for 30 minutes. Cold-water immersion is typically a short treatment to reduce the risk of hypothermia, which is why it was offered for just 15 minutes.
After 72 hours, those who simply rested had recovered strength to a similar extent as those in the hot-water and hot-air groups, with all three groups regaining around 89 per cent of their maximum muscle strength. The cold-water group recovered about 82 per cent of their maximum strength.
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Self-reported pain and muscle soreness significantly increased in all groups at 24 hours after exercise, with none of the groups reporting a significant reduction by 72 hours. The cold-water group did report less pain at 24 hours relative to the other groups, but this had increased by 48 hours, suggesting the cold-water therapy had only temporarily masked pain.
Blood samples showed that levels of creatine kinase-MM, an enzyme in skeletal muscle cells that enters the bloodstream when muscles are damaged, returned to normal levels faster in the hot-water group than in the control and hot-air groups. In the cold-water group, levels remained 25 per cent above normal, even after 72 hours.
It is possible that changes to the interventions, such as repeating them or applying heat or cold therapies more locally to the affected area, would also change the results, says Bayne.
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Ken Nosaka at Edith Cowan University in Western Australia says that much of the evidence supporting cold therapies is anecdotal. “It is interesting that the authors found that none of the thermal recovery strategies were effective in alleviating pain and muscle soreness, but importantly none of them had negative effects,” he adds.
But it remains to be seen whether each recovery strategy has longer-term benefits, or whether different types of exercise would have different outcomes. “Athletes and recreational exercisers experience muscle fatigue and recovery demands in many different contexts,” says Bayne.
Mike Tipton at the University of Portsmouth, UK, says the findings shouldn’t stop athletes using ice baths altogether. “[It] may assist with repeated bouts of continuous activity in the heat as well as blunt perceived muscle soreness and fatigue during multi-day events where rapid recovery is required,” he says.
Journal of Thermal Biology DOI: 10.1016/j.jtherbio.2026.104551