Getting older will undoubtedly make you slow down a little, but that’s no excuse to stop moving altogether. In fact, being sedentary could advance your biological age by as much as eight years.

In a recent study published in the American Journal of Epidemiology, researchers studied cell function and sedentary time in 1,481 women with an average age of 79. Specifically, they looked at the length of their telomeres, which are sequences of DNA at the end of chromosomes that help protect them from deterioration. (Think of them like the plastic casing on the end of a shoelace.)