The prevalence of obesity is now three times greater than it was 20 years ago and it appears to be increasing more rapidly in England than anywhere else in Europe. The Food Standards Agency has predicted that by 2010 obesity will cost the taxpayer pound;3.8 billion per annum. We have a crisis. Ministers are “concerned”. But, have we not been here before?

Almost 20 years ago the children’s health and exercise research centre at Exeter University initiated its studies of children’s habitual physical activity. The research team fixed small transmitters to children’s chests and transmitted their heart rates to receivers which the children wore as watches on their wrists.

To estimate daily physical activity heart rates were monitored continuously for 12 hours a day for at least three weekdays and a weekend day. The results showed clearly that many children had adopted sedentary lifestyles.

Boys were generally more active than girls even at primary school age and the frequency and intensity of activity of both sexes gradually decreased with age with a marked reduction during the teen years, particularly in girls. The media coined the phrase “couch potatoes” to describe the data.

The research team was invited to share its concerns with MPs of all parties in seminars at the House of Commons. A minister visited the research centre, the Duke of Edinburgh was briefed at Buckingham Palace, a private meeting at Westminster was arranged with the Conservative minister of sport, questions were asked in both houses of Parliament and Labour’s shadow secretary for health told MPs that the Government’s policy on physical education was “running out of puff”. But what have governments of either party done over the past decade to address the inevitable consequence of low levels of physical activity in children?

The most effective way to approach the problem of obesity is to prevent it in the first place. It is clear that promoting physical activity in children plays a crucial role in the lifelong prevention of obesity. This is not as straightforward as it seems, as the successful promotion of physical activity requires a contribution from environmental, behavioural, social, cultural, legislative and financial factors.

However, all children attend school from an early age and the school setting provides a golden opportunity for influencing young people’s behaviour. All schools should endeavour to develop a physical activity policy, provide an environment conducive to physical activity and establish appropriate partnerships, community links and inter-school liaisons.

Nevertheless, even in an active school physical educators are likely to provide the fulcrum for the promotion of physically active lifestyles. In the primary school it is important to build a foundation of motor skills and to make children’s early activities enjoyable in order to foster future participation; but serious concerns have been expressed over facilities for PE in primary schools.

The transition from primary to secondary often coincides with a decrease in physical activity. Good primary-secondary liaison and a more gradual change of emphasis in the PE programme may be beneficial in addressing the issue but in a recent survey 50 per cent of secondary schools reported limited or no contact with their feeder primaries.

In secondary schools, the time allocated to PE varies considerably with few schools meeting the recommended 8-10 per cent of curriculum time. A consistent trend is a decrease in curriculum time through the school. While outdoor facilities are generally felt to be at least adequate, many PE departments feel their indoor facilities to be inadequate.

The moderate to vigorous physical activity content of secondary school PE lessons has been criticised but although high activity content is an important component of lessons it is curriculum content and enjoyment which are the most influential factors in developing positive attitudes towards physical activity.

Young people need to be exposed to a balanced programme of competitive, co-operative, individual, partner and team activities, thus laying the foundation for present and future physical activity behaviour. Recent years have witnessed some positive and encouraging developments in the promotion of physical activity but much remains to be done.

The message is loud and clear and politicians must not be allowed to waste another decade before they act. Britain is fortunate to have an excellent and dedicated PE profession. Local and national government must turn “concerns” into resources to enable physical educators to meet the challenge of the obesity epidemic. The future health of our children depends on it.

Professor Neil Armstrong is director of the children’s health and exercise research centre at the University of Exeter.