How many hours a day do you spend sitting down?
If it's more than 10, you could be speeding up the ageing procedure by as much as 8 YEARS. That's the message coming from researchers who studied the lifestyles of 1,481 women aged over 64.
"Our study found cells age faster with a sedentary lifestyle," said Dr Aladdin Shadyab, from the University of California, San Diego who led the study.
"Chronological age doesn't always match biological age," he says.
The study found that idleness led to smaller telomeres – which are tiny protective caps found on the ends of DNA strands. Without them, cells age faster and therefore are more susceptible to the likes of heart disease or diabetes.
Gratefully, all is not lost if you regularly find yourself sitting for long periods. The researchers said that just half an hour of moderate exercise (even going for a walk counts) could undo the damage.
"We found that women who sat longer did not have shorter telomere length if they exercised for at least 30 minutes a day," said Shadyab.
"Discussions about the benefits of exercise should start when we are young, and physical activity should continue to be part of our daily lives as we get older, even at 80 years old."