Elite athletes, including the Irish rugby team, are wasting their time by plunging into icy water after intense exercise and may even be putting their health at risk.
Scientists at the University of Portsmouth found cold-water immersion is no more or less effective for recovery after sport than light cool-down exercise.
They also warn ice baths might do more harm than good. Lead author Jo Corbett said they "pose a number of potentially serious health risks".
Cold water has been thought to reduce inflammation, swelling and muscle spasms, and therefore pain, meaning an athlete can perform again at a high level more quickly.