Tony Blair this week confirmed that the Government would be increasing spending on sport in schools by pound;500 million. By the end of the decade all children will be expected to do two hours PE a week at school and have access to two to three hours of after-school sport.

The funding will also help increase the number of specialist sports colleges from 287 to 400, provide extra training for PE teachers, and get more professional sports clubs and coaches to visit schools.

The Prime Minister, who donned a tracksuit to make the announcement at Waverley school in Southwark, said that sport was not just important for the way it taught children to win, lose and act as a team.

“It is also important for tackling obesity in young people,” he said.

However, a study by Peninsula medical school in Plymouth said there was only a 3 per cent difference in physical activity between pupils at one school and another offering double the amount of sport because children compensated in their spare time.

“The evidence at present suggests that neither better facilities and nor an increase to four hours in the amount of weekly time allocated to PE will improve physical activity levels in children and thereby impact on the rising tide of obesity,” it said.

The report recommended that more work is done instead on understanding why some children set themselves low limits for their physical activity.

Education ministers wrangled with their counterparts in the Department for Culture, Media and Sport over the four-hour target because of fears it would add to schools’ workloads.

Charles Clarke, the Education Secretary, flatly dismissed reports of the plan when he spoke last month at the Specialist Schools Trust conference.

Education and Health vol 22 is at www.sheu.org.ukpubs