New research from the University of Exeter and University College London has challenged claims that sitting for long periods increases the risk of an early death even if you are otherwise physically active.

The study, which is published in the International Journal of Epidemiology, followed more than 5000 participants for 16 years (making it one of the longest follow-up studies in this area of research) and found that sitting, either at home or at work, is not associated with an increased risk of dying.

These findings challenge previous research suggesting that the act of sitting itself causes harm even when people routinely walk a lot or do other exercise. Importantly, the findings contradict NHS recommendations which state that remaining seated for too long is bad for your health, regardless of how much exercise you do.

Dr Melvyn Hillsdon from Sport and Health Sciences at the University of Exeter said: "Policy makers should be cautious in recommending a reduction in the time spent sitting without also promoting increased physical activity."

"Our study overturns current thinking on the health risks of sitting and indicates that the problem lies in the absence of movement rather than the time spent sitting itself. Any stationary posture where energy expenditure is low may be detrimental to health, be it sitting or standing.

"The results cast doubt on the benefits of sit-stand work stations, which employers are increasingly providing to promote healthy working environments."

Lead author Dr Richard Pulsford from Sport and Health Sciences at the University of Exeter said: "Our findings suggest that reducing sitting time might not be quite as important for mortality risk as previously publicised and that encouraging people to be more active should still be a public health priority."

The study participants provided information on total sitting time and on four other specific types of sitting behaviour (sitting at work; during leisure time; while watching TV; and sitting during leisure time excluding TV) as well as details on daily walking and time spent engaged in moderate to vigorous physical activity. Age, gender, ethnicity, socioeconomic status, general health, smoking, alcohol consumption and diet were all taken into account. The study showed that over the 16 year follow-up period none of these five sitting measures influenced mortality risk.

Future work will consider whether long periods of sitting are associated with increased incidence of diseases such as heart disease and type II diabetes, and will investigate the biological mechanisms that underpin previously observed associations between sitting time and health outcomes.

The participants included 3720 men and 1412 women drawn from the Whitehall II study cohort which is supported by grants from the Medical Research Council, British Heart Foundation, Stroke Association, National Heart Lung and Blood Institute and the National Institute on Aging.