A report released by Ofsted recommends the government develop a new national strategy on PE and sports in schools, with teaching in more than a quarter of schools not improving pupils’ fitness.

The Beyond 2012 report, released today, found PE and sport had benefited from “considerable” investment over the past decade but said the Department of Education needed to harness momentum from the Olympics and Paralympics.

According to the report, one fifth of primary schools did not ensure all pupils learnt to swim, many teachers lacked specialist PE knowledge and only a minority of schools played competitive sport to a high level.

Her Majesty’s chief inspector Sir Michael Wilshaw said PE lessons often did not involve enough strenuous activity.

“In many of the schools visited, the more able pupils were not challenged sufficiently because teachers’ expectations of them were too low.”

However, he said the report found more good and outstanding PE than at the last time of the survey in 2008.

The report also found very few schools had adapted PE programmes to suit the needs of overweight and obese students – despite the NHS classifying three out of 10 children as obese.

Chair of the Youth Sport Trust Baroness Sue Campbell welcomed Ofsted’s recommendation for a national strategy on PE and sport.

“From our own research we know that primary school teachers are not receiving adequate training in how to deliver an effective PE experience and this can leave teachers lacking the confidence and competence to deliver the subject effectively.”

Ofsted has commissioned a follow-up report examining the quality of competitive sport in the state sector compared with that offered in the independent sector.

Ukactive chief executive David Stalker said: "Introducing the benefits of physical activity at an early age is one of the key ways of embedding a long term healthy lifestyle.

"If things continue as they are now, obesity related illnesses are projected to cost the NHS £50 billion by 2050.

"Schools hold a unique position within communities and it is important that we act upon the findings of this report as soon as possible, in order to avoid a public health crisis in the future."

Chief executive of British swimming body ASA David Sparkes said swimming lessons should be part of Ofsted's school inspections.

“Learning to swim can mean far more than just improving the physical health of an individual, it is also about giving them a life saving skill," he said.

The English Federation of Disability Sport supported the report’s recommendations for a minimum two hours physical education each week.

Chief executive Barry Horne said: “Providing an environment in which everyone has the opportunity to be challenged appropriately and make good progress is important.

“We are committed to showing inclusion and competition matter – in every form.”