Don't just sit there! It could be harmful later in life

• Adults over age 60 spend an average of two-thirds of waking time being sedentary
• Each additional hour of sedentary time doubles the risk of being disabled
• Exercise more and sit less for better health as you age

Sitting too much, sometimes called sitting disease, may increase the risk of disability in people over age 60, a new study suggests.

Adults this age spend an average of two-thirds of their waking time being sedentary -- roughly nine hours a day, the research showed.

Every additional hour adults over age 60 spend sitting increases by 50% their risk of being disabled for activities of daily living such as bathing, dressing and walking, says the study's lead author Dorothy Dunlop, a professor of medicine at Northwestern University Feinberg School of Medicine. Too many people "have very low levels of activity," she says.

The health problems associated with sitting disease are mounting. Research has linked too much sitting to increased risk of heart failure, type 2 diabetes and death from cancer, heart disease and stroke. It may affect mood and creativity. One study showed that if most people spent fewer than three hours a day sitting, it would add two years to the average life expectancy in this country.

Dunlop and colleagues reviewed data on more than 2,200 people, age 60 and older, who participated in the government's National Health and Nutrition Examination Survey.

The participants wore accelerometers (motion sensors) during their waking hours for one week during the three-year survey period. This measured the time they spent being sedentary, doing light physical activity such as pushing a grocery cart, doing moderately vigorous physical activity such as brisk walking, or vigorous physical activity such as running.

Among the findings out Tuesday in the Journal of Physical Activity and Health:

• 6.2% of participants met the government's physical activity guidelines, which advise adults to get at least 2½ hours of moderate-intensity physical activity each week, such as brisk walking, or 1¼ hours of a vigorous-intensity activity, such as jogging or swimming laps, or a combination of the two types.

• 3.6% reported having disabilities in activities of daily living (eating, bathing, dressing, walking).

• The odds of a person being disabled were almost 50% greater for each hour spent in sedentary behavior, Dunlop says. This was true after researchers controlled for physical activity, obesity, socioeconomic status and other health factors.

So if you take two women who are 65 years old who spend the same amount of time doing exercise and have the same health profile, if one was sedentary for 12 hours a day, her chance of being disabled is about 6%, Dunlop says. If another person with exactly the same health profile spent 13 hours a day being sedentary, her chance of being disabled was 9%.

This study doesn't not prove cause and effect, she says. It could be that disabled people are more sedentary, but there are good reasons to believe that being sedentary could lead to disability, Dunlop says.

"Older adults should be as physically active as possible," she says. "We know that moderate physical activity, such as brisk walking, is good for your health, and being sedentary is bad for your health. People should find opportunities to replace some of their sitting time with light activity. It's a low-cost strategy to good health."

This study is "further evidence that simply getting off the couch has great health benefits," says Tim Church, a physician and director of preventive medicine research at the Pennington Biomedical Research Center in Baton Rouge. "The only known prescription for maximizing quality of life as we age is the prescription of physical activity."

This research is "heavy hitting" because it is "telling us that being sedentary is debilitating when one is elderly," says James Levine, co-director of Obesity Solutions at Mayo Clinic in Phoenix and Arizona State University. He did some of the first research on sitting disease but was not involved in this study. "This is the first time that has been well illustrated."

Levine says if you've been sitting for an hour, you've been sitting too long. He recommends getting up for 10 minutes of every hour.

Dunlop offers these suggestions for replacing some sitting time with light activity:

• If you are watching TV, get up and walk around the house when a commercial comes on.

• When you are working in front of a computer, get up and walk around every hour.

• When you go to grocery store or mall, park in a space that is far away.

• When you get up to have glass of water or for a meal, walk around the house or office.

• Take the stairs instead of the elevator, if you are able.