Sitting about doing nothing is as damaging to health as smoking, doctors say.

Physical inactivity may be responsible for as many as one in 10 deaths worldwide – mainly from heart disease, diabetes and breast and bowel cancer. If exercise – such as brisk walking for 30 minutes, five days a week – could be bottled, it would be a miracle cure. A series of research papers published in The Lancet today show that millions of lives could be saved if people were stimulated by the spirit of the Olympic Games to get active.

Around a third of adults globally and four out of five adolescents are doing so little they put themselves at significantly greater risk of disease.

The UK has one of the most inactive populations with 63 per cent of adults failing to do enough. Improved street lighting, cycle lanes and more green space can boost activity levels by 50 per cent. Simple measures such as signs encouraging people to use the stairs rather than the lift can also have an impact.

One of the most effective interventions, known as ciclovia, which originated in Colombia and translates as "cycle path", involves closing city streets to vehicles on Sunday mornings and holidays and opening them to walkers, runners, skaters and cyclists.