Even if you are physically active, sitting for more than six hours can increase your risk of heart disease and diabetes

Sitting down for at least six hours a day results in tens of thousands of people dying every year and costs the NHS £700 million annually, analysis concludes.

Office workers must be encouraged to stand up every hour and spend their free time walking to make up for the effects of long days behind a desk, researchers said. Employers should allow activity breaks and accept that yoking staff to their screens all day will one day go the way of offices wreathed in cigarette smoke, they added.

People are already advised to spend 2½ hours a week walking or half that time in more vigorous exercise such as running. However, evidence is emerging that long hours spent sitting are bad for you over and above