July 9, 2012 -- Sitting too much is a serious health threat, a new study suggests.
But keeping "down time" to less than three hours a day might make us live an extra two years. And cutting TV viewing -- which most of us do while sitting -- to less than two hours every day might extend life by almost 1.4 years.
The new findings appear in the online journal BMJ Open.
American adults spend on average about 55% of their time being sedentary, or inactive.
Being sedentary, which can include sitting for long periods of time, has been linked to diabetes and death from heart disease or stroke. The new study takes it a few steps further by showing just how much we can benefit by sitting less frequently.
"Sitting is a risk factor, not a disease," says Peter Katzmarzyk, PhD. He's an associate executive director for population science at Pennington Biomedical Research Center at Louisiana State University System in Baton Rouge, La. "It's comparable to obesity, and it's almost to the level of smoking," he says.
"We sit to eat and don't tend to stand up a whole lot," he says. "We need to turn that around and engineer sitting out of our lives."
Sit Less, Move More, Live Longer
What would a world with less sitting look like?
Some companies are replacing standard desks and chairs with treadmill desks or standing desks, Katzmarzyk says. "Rather than emailing a colleague, go talk to them," he says. Walking meetings can also take the place of sitting around a table.
The researchers used data from the National Health and Nutrition Examination Survey (NHANES) for 2005-2006 and 2009-2010 to see how much time U.S. adults spent watching TV and sitting down. They also analyzed five studies of 167,000 adults that looked at sitting time and deaths from all causes.
They estimated the theoretical effects that a factor such as sitting would have at a population level.
The new findings add to a growing body of literature on the possible health problems that occur when we sit too much, says Scott Kahan, MD, MPH, director of the National Center for Weight and Wellness in Washington, D.C.
"Independent of weight and independent of physical activity and all of these other things that can lead to long-term health problems, the more we sit, the more likely that bad things happen in the body," he says.
Garry Sigman, MD, director of the pediatric obesity program of Loyola University Medical Center in Maywood, Ill., agrees. "We evolved from a place where we needed to walk around a lot and not sit still to survive, and now in modern society, there is more opportunity where we sit and that is not healthy for more than one reason," he says.
"When we move, we feel better," Sigman says. His advice: If you have a desk job, take a walk during lunch hour. "If you are sitting because of your pastimes, try to adopt and enjoy a more active pastime like walking or bicycling."