It is important that they have a proper rest and recovery period - and that they are well nourished while they train

John Brewer, National Sports Centre, Lilleshall

However, Professor Nicola Maffulli, writing in the British Journal of Sports Medicine, suggests there is no evidence of a link.

The professor writes: "In general, the differences observed in stature between athletes and non-athletes are mainly the result of nature rather than nurture.

"With regard to pubertal development, the evidence suggests that the tempo is slowed down in some sports, but it has not yet been possible to identify whether this is an effect of nature or nurture."

Natural selection

The professor said that the fact that so many elite gymnasts were smaller than average was probably at least partly due to the fact that smaller girls were most likely to progress to the heights of the sport - and taller girls more likely to drop out or take up other sports.

And while many female athletes experienced a later than average onset of puberty, the authors said there were other potential reasons for this which at least cast doubt on excessive training as a cause.

Other UK experts, such as John Brewer, from the National Sports Centre at Lilleshall, Shropshire, also gave their stamp of approval to intensive training programmes.

He told BBC News Online: "I think that young female athletes can train five or six days a week with one day off.

"It is important that they have a proper rest and recovery period - and that they are well nourished while they train.

"If anything it is the rest and nutrition that are the most important factors rather than the frequency of training."