The more you sit, the more you age. That’s the upshot of a recent study that found older women who sit more than 10 hours a day and get little physical activity have cells that are biologically older.

Just how much older are their cells compared with more active women? Typically about eight years, according to findings by University of California – San Diego researchers published in the American Journal of Epidemiology.

Older women who sat more than 10 hours a day and got less than 40 minutes of moderate-to-vigorous activity have shorter telomeres (telo-meers). Those are the caps at the end of DNA strands the prevent chromosomes from deteriorating. Shortened telomeres have been associated with diabetes, heart disease and cancer.

In their study of nearly 1,500 women between the ages of 64 and 95, the researchers found what they believe is the first objective measurement of how a lack of exercise and extended sedentary time can accelerate a key indicator of aging. Women in the study answered questionnaires and wore an activity-measuring device continuously for seven days.

There is some good news from the study: Some of the ill effects of prolonged sitting can probably be avoided with just some moderate effort. Women who sat a long time each day but also exercised for 30 minutes did not have shortened telomeres. That, researchers said, underscores the idea that making physical activity a daily habit should continue well into old age.

So while the sofa may look inviting as you head into your older years, consider the consequences. A regular exercise routine might help keep you, and your cells, spry.