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July 12, 2012

Study Suggests Sitting Less Can Extend Life

by Rebecca Widiss

What’s the best seat in the house? It may be whichever one you use the least. New research suggests that cutting daily sitting time to less than three hours might extend your life by two years.

Humans were designed to move. But modern lifestyles and office jobs rarely prompt us to roam around. Quite the opposite, says Peter Katzmarzyk, an epidemiologist at the University of Louisiana.

"Sitting is ubiquitous in our lives today. You know, we sit while we’re eating, we sit in the car, we sit while we watch TV. And many of sit for many hours at work. So on average, Americans report they sit between four and a half to five hour a day," Katzmarzyk said.

And, he says, those chair-centered days matter to our health, just like exercise.

"We can’t throw away physical activity. It’s extremely important. We have 60 years of research showing us that. But sedentary behavior is also important… Even if you exercise for 30 minutes a day. What goes on in the other 23 and a half hours a day is also very important," Katzmarzyk said.

Katzmarzyk and his colleagues are part of new generation of researchers trying to discover how sitting all day affects our lifespans.

"This is a relatively new area of study… Studies that have assessed the relationship between sitting and mortality or television viewing and mortality are very rare. There’s only been a few of them, actually five or six now, in the last four or five years," said Katzmarzyk.

Karzmarzyk and his colleagues pooled data from these studies, which involved almost 167,000 adults. Then they turned to a government-run survey of Americans to find out exactly how much time people spend sitting and watching TV.

Not only did the team find that U.S. citizens could live longer by sitting less, they found that cutting TV-time to less than two hours a day could add an extra 1.4 years to their lives.

People who’ve spent half their waking lives sitting down might well ask, “Is it ever too late to make a change?”

"That’s a good question. Physical activity data would say “No. It’s never too late.”  Physical activity is good for you at every age. We don’t know that yet about sitting. But one might assume it to be similar," Katzmarzyk said.

Change is already afoot in some offices, especially when it comes to desk designs.

"That’s one of the strategies that many companies are using now. They may have got five standing desks for their employees or a treadmill desk. I’ve heard of other companies where they may not have a desk for every person. But they’ll have a bank of these desks where people can go for an hour a day and answer their emails or talk on the phone," Katzmarzyk said.

Katzmarzyk says simply studying this problem has inspired his team to make a few changes in their own lives.

"As a university professor, you know, it is a very sedentary occupation. We’re chained to a desk in terms of writing papers and doing research. We really try to limit the amount of time we spend doing that, said Katzmarzyk.

Katzmarzyk and his team recommend a few simple changes:  frequently getting up from your desk, taking walks at lunch time, and instead of e-mailing colleagues,  walking over to their offices and talking face-to-face - all activities that can be enjoyable as well as life-extending.  Research on the benefits of reduced daily sitting time is published in the online journal, BMJ Open.