Paula Radcliffe may say they are the secret of her success, but Australian research is questioning the benefits of taking an ice bath after exercise.

Physiotherapists recommend the bath as a way to speed up recovery, claiming the icy cold helps shift lactic acid.

But this is unproven, and a study in the British Journal of Sports Medicine now claims the opposite may be true.

Out of 40 volunteers, those who took an icy plunge reported more pain after 24 hours than those who took a tepid bath.

Although physiotherapists who promote the bath have had little evidence to prove this, there is plenty of anecdotal evidence from the athletes themselves that the bath makes them feel better.

In line with this theory, the study carried out at the University of Melbourne had expected to find a 25% reduction in pain after 48 hours among those who had the ice immersion.

Instead it found that there was no difference in physical pain measurements such as swelling or tenderness, and in fact those who had been in the ice reported more pain when going from a sitting to a standing position after 24 hours than those who had the tepid treatment.

"This study challenges the use of ice-water immersion in athletes," wrote the researchers.

"Ice-water immersion offers no benefit for pain, swelling, isometric strength and function, and in fact may make more athletes sore the next day."

It was unclear why the ice may had this effect, and the researchers said further study was needed.

John Brewer, Director of the Lucozade Sports Science Academy, said he did not find it surprising that there was no difference between the two samples.

"I don't find it hard to believe that the ice doesn't have any long-term benefit, although I would question whether the ice group really did feel more pain after 24 hours than the tepid group. The problem with pain is that it is subjective and very hard to measure," he said.

"And because it's subjective, there may even be a placebo effect on those who take the cold bath. It's part of their ritual, it finishes off the endurance test, and many clearly report that it makes them feel better."