Each hour spent sitting could raise the risk of having trouble with tasks like dressing and eating regardless of physical activity levels, a study of people aged 60 and older suggests.

In Wednesday's issue of the Journal of Physical Activity & Health, researchers called it the first study to document how sedentary behaviour is related to increased disability regardless of the amount of time spent in moderate activity, based on objective measurements.

Increasingly, researchers view being sedentary as more than a just a synonym for lack of physical activity.

The study looked at 2,286 adults aged 60 and older from the U.S. National Health and Nutrition Examination Survey. It compared people in similar health with the same amount of moderate vigorous activity, such as a brisk walking pace.

When participants wore accelerometers over seven days, the average time spent being sedentary during waking hours was almost nine hours. About 3.6 per cent reported "disabilities in activities of daily living" — difficulty or inability to get in and out of bed, eat, dress or walk that threaten personal independence. Other surveys also looked at bathing or toileting.

Despite the benefits of physical activity to promote health, the older adults spent almost two-thirds of their waking time being sedentary.

"Sedentary behaviour, such as sitting, is problematic and costly," the study's authors concluded.

Clinically, a sedentary lifestyle contributes to markers of poor health, the researchers said.

"It's so woven into our fabric of life with television, and electronics and computers and information age and social media. People are inundated with opportunities to be sedentary," study co-author Pamela Semanik, an assistant professor in  adult health and gerontological nursing at Rush University in Chicago, said in an interview.

"It's important to understand how those kinds of quote unquote conveniences have made it possible to avoid being mobile and moving your body the way it was designed to move." 

5 tips to move more and sit less

Replacing 30 minutes per day of sedentary time with equal amounts of light activity is associated with better physical health. To that end, the researchers suggested five ways to cut back on sitting time:

  •     Stand up when you talk on the phone or during a work meeting.
  •     When you go to grocery store or mall, park in a space farthest away.
  •     When you get up to have glass of water, walk around the house or office.
  •     Walk for short errands instead of taking the car.
  •    Take the stairs instead of the elevator, if you are able.

Overall in the study, the odds of disability were 1.52 times greater for every one hour increase in sedentary time, independent of time spent in moderate-vigorous activity, the researchers found.

While the data was only examined at one point in time, it does corroborate animal studies suggesting immobility is a separate risk factor for ill health.

Other teams have shown that objectively measured sedentary time is related to metabolic syndrome, depression, cancer and mortality. 

The new U.S. study looked at an important health outcome that affects quality of life, said Ian Janssen, who holds the Canada Research Chair in Physical Activity and Obesity at Queen's University in Kingston, Ont.

"It's a pretty consistent message," said Janssen. "The time you spend sedentary when you're awake is a risk factor for bad health."

Janssen said age 60 was chosen because that's the age where disabilities start to become measurable.

Business analyst Gary Akai, 60, figures he sits more than eight hours a day at his desk and in front of a TV in Toronto.  Despite playing hockey, doing yoga, pilates and spinning he recognizes that "I could get off my butt a bit more."

With files from CBC's Kas Roussy