A study which followed more than 5,000 people for 16 years found sitting is not associated with an increased risk of dying.
The findings challenge previous research suggesting sitting causes harm, even if people are otherwise physically active.
Instead, problems lie in not moving, whether while sitting or standing, say the researchers from universities in Exeter and London.
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,” said Dr Hillsdon.
“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.”
The research was published in the International Journal of Epidemiology.