• Sitting for an extra hour a day if you’re over 60 ‘doubles the risk of being disabled’ even if you take moderate exercise
If you’re 60 and older, every additional hour a day you spend sitting is linked to doubling the risk of being disabled, according to a new study.
And the snag is that moderate exercise won’t protect you from the hidden hazards of prolonged sitting, the study reveals.
It is the first to show sedentary behaviour is its own risk factor for disability, separate from lack of moderate vigorous physical activity.
In fact, immobility is almost as strong a risk factor for disability as lack of moderate exercise.
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 per cent more likely to be disabled, the study found.
Dorothy Dunlop, professor of medicine at Northwestern University Feinberg School of Medicine and lead author of the study, said: ‘This is the first time we’ve shown sedentary behaviour was related to increased disability regardless of the amount of moderate exercise.
‘Being sedentary is not just a synonym for inadequate physical activity.’
Prof Dunlop said she was surprised by the findings.
‘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.
The study focused on a sample of 2,286 adults aged 60 and older from the US National Health and Nutrition Examination Survey.
It compared people in similar health with the same amount of moderate vigorous activity. Moderate activity is walking briskly, as if you are late to an appointment.
The participants wore accelerometers from 2002 to 2005 to measure their sedentary time and moderate vigorous physical activity, says a report in the Journal of Physical Activity & Health.
The accelerometer monitoring was an objective measure of sedentary behaviour because the older and heavier people are, the more they tend to overestimate their physical activity.
Previous research suggested a relationship between sedentary behaviour and disability but it was based on self-reports and could not be verified.
Because the study examines data at one point in time, it cannot determine that sedentary behaviour causes disability but ‘draws attention to a potential problem’ said Prof Dunlop.
Studies with animals have shown immobility is a separate risk factor for negative effects on health. ‘This is the first piece of objective evidence that corroborates the animal data’ she added.
There has been growing interest in the downsides of prolonged sitting, which could be both a marker for a sedentary lifestyle and an independent risk factor.
Previous research found people who watch six hours of TV a day cut short their lifespan by five years compared with someone who watches no TV.
People who sit for longer have bigger waist sizes, and higher levels of cholesterol, blood sugar and triglycerides.
The average adult spends 90 per cent of their leisure time sitting down and less than half of adults meet World Health Organization physical activity recommendations.
