PEOPLE who spent a lot of time sitting at a desk or in front of a TV were more likely to die young than those who were sedentary a few hours a day.
Researchers found that the link between too much time sitting and shortened lives stuck even when they accounted for how much exercise people got, as well as their weight and other measures of health.
That suggests that shifting some time from sitting to light physical activity, such as slow walking or active chores, might have important long-term benefits, they added.
"When we give people messages about how much physical activity they should be doing, we also need to talk to them about reducing the amount of hours they spend sitting each day," said Hidde van der Ploeg, the study's author from the University of Sydney in Australia.
Of more than 200,000 adults aged 45 and older, van der Ploeg and her colleagues found that people who reported sitting for at least 11 hours a day were 40pc more likely to die during the study than those who sat less than four hours daily.
That doesn't, however, prove that sitting itself cuts people's lives short, she noted, adding that there could be other differences between people who spend a lot or a little time sitting each day.
The team surveyed about 220,000 people from New South Wales, Australia, between 2006 and 2008, including questions about participants' general health, whether they smoked and how much time they spent both exercising and sitting.
Then the research team tracked responders using mortality records for an average of almost three years, during which 5,400 -- between 2 and 3pc -- died.
They found that the extra risk tied to sitting held up regardless of whether people were normal weight or overweight, how much time they spent working out and whether they had medical conditions.
The findings are consistent with other recent studies suggesting health consequences from too much sitting, said Mark Tremblay, an obesity researcher at Children's Hospital of Eastern Ontario, Canada.
"Sitting or reclining, especially in front of screens, is bad for you regardless of your age," said Tremblay.