Sitting less could lead to a longer life, a study out Monday says.
If most people spent less than three hours a day sitting, it would add two years to the average U.S. life expectancy. And if they cut the time they spent on the couch watching TV to less than two hours a day, it would add about 1.4 years to overall life expectancy, the research found. This is far less than the six hours a day that many people now sit.
"Sitting is a dangerous risk factor for early death, on par with smoking and being obese," says Peter Katzmarzyk, a researcher at the Pennington Biomedical Research Center in Baton Rouge and lead author of the study, published online in BMJ Open.
It is the latest in a string of studies looking at the dangers of "sitting disease," sitting too much or too long. Research links it to increased risks of diabetes and death from cancer, heart disease and stroke.
In the new research, scientists looked at several studies that evaluated sitting and all causes of death. They also reviewed government data that show almost half of us report sitting more than six hours a day; 65% spend more than two hours a day watching TV.
Using a statistical model, they found that if people sat for less than three hours a day, average life expectancy would be 80.5 years instead of the current 78.5 years.
"Sitting a lot doesn't mean you'll die earlier, but it increases the risk," Katzmarzyk says.
He says many people sit nine or more hours a day, especially those who work long hours at a desk job, travel frequently or watch a lot of TV. Those in sedentary occupations are at highest risk of early death.
James Levine, a professor of medicine at Mayo Clinic in Rochester, Minn., who did some of the first research on sitting disease but was not involved in this study, says, "It's extraordinary to see the coming to life of the concept that your chair really does appear to be killing you, one year after another."
"Sitting is diminishing the health of the nation," he says.
Other data show that getting up intermittently throughout the day might reduce the risks of prolonged sitting.
"No one knows how much we should be up, but we do know we are down too much," he says. "If you've been sitting for an hour, you've been sitting too long."
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