Schools are not offering children sufficient levels of exercise, it has been suggested.
Kevin Giles, an international sports coach who has worked with elite sports men and women around the world, told the BBC that PE lessons are barely managing to raise heart rates.
He said: "Out of the 40 minutes there's eight minutes of activity going on.
"Very often the kids are standing around and just listening to the teacher talk. So heart rates aren't being raised. Mechanical efficiency isn't being looked at."
The news follows a decision by the government to cut the sports budget for schools.
However, education Michael Gove claimed that the reduction in funding should not reduce participation levels among pupils.
Exercise has become a hot topic in the UK as obesity levels are rising among adults and children.
According to the Food Standards Agency, levels of childhood obesity in particular have tripled in England since 1980.
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