by Nanci Hellmich
If most people spent less than three hours a day sitting, it would add two years to the average life expectancy in this country. 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 are currently spending in their seats.
"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 Monday in BMJ Open. Smoking also cuts about two years off of life expectancy, he says.
This is the latest in a string of studies that has investigated the health dangers of "sitting disease," which is sitting too long or too much. Research has linked it to an increased risk of diabetes and death from cancer, heart disease and stroke.
For the latest research, scientists looked at several studies that evaluated sitting and all causes of death. They also reviewed government data that shows almost half of people report sitting more than six hours a day. And 65% say they spend more than two hours a day watching TV.
Using a statistical model, the researchers found that if people sat for less than three hours a day, the average life expectancy in this country would be 80.5 years instead of the current 78.5 years.
This research doesn't prove that sitting causes early death but it shows a link, Katzmarzyk says. "Sitting a lot doesn't mean you'll die earlier, but it increases the risk."
He says many people spend nine or more hours a day in their seats, especially those who work long hours at a desk job, travel frequently or watch a lot of TV. The people in sedentary occupations are at the highest risk of early death, he says. "Even just standing up to work at your desk or moving around as you work is better for your health."
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. It's not just a problem here but an issue in many other countries, Levine adds.
Levine says other data shows that getting up intermittently throughout the day might reduce the ill effects 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," Levine says. "My gut feeling is you should be up for 10 minutes of every hour."
Katzmarzyk says there are interventions that make it easier to avoid being in your seat so much, including holding meetings while you walk and getting up to talk to a colleague instead of sending an e-mail. Some companies even offer a treadmill at your desk.