Sitting for long periods of time may be particularly dangerous for people over 60, even if they spend some time exercising, suggests a US study on Wednesday.
The odds of being disabled doubled for each additional hour of sedentary time in seniors, said the research in the Journal of Physical Activity & Health.
For instance, "if there are two 65-year-old women, one sedentary for 12 hours a day and another sedentary for 13 hours a day, the second one is 50 percent more likely to be disabled," explained a statement from the research team at Northwestern University.
Disability was defined as being limited in basic activities such as eating, dressing, bathing, getting in and out of bed and walking across a room.
The study was based on a sample of 2,286 adults aged 60 and older from the National Health and Nutrition Examination Survey.
Because it only observed the participants at one moment in time, they could not conclusively show whether the sedentary behavior actually caused the disability.
Lead researcher Dorothy Dunlop, professor of medicine at Northwestern University Feinberg School of Medicine, has a long-term study underway to look and cause and effect.
She said she was surprised to see that being sedentary was almost as strongly correlated with disability as was the lack of moderate vigorous activity, such as walking.
"It means older adults need to reduce the amount of time they spend sitting, whether in front of the TV or at the computer, regardless of their participation in moderate or vigorous activity," she said.