Elderly women who sit more than 10 hours a day have accelerated biological aging, according to an epidemiology paper. They have older cells? 

It's the increasingly popular shorter telomeres hypothesis. Telomeres are tiny caps found on the ends of DNA strands, like the plastic tips of shoelaces, that protect chromosomes from deterioration. It has been found that they progressively shorten with age, just one of the reasons why we are considered to be biologically programmed to die. 

Nearly 1,500 women ages 64 to 95 who are part of the Women's Health Initiative (WHI), a national, longitudinal study investigating the determinants of chronic diseases in postmenopausal women, participated in the study. They completed questionnaires and wore an accelerometer on their right hip for seven consecutive days during waking and sleeping hours to track their movements.

That is a confounder, not to mention logical fallacies like noting that other studies claim telomeres cause everything from diabetes to cancer. Do smoking and obesity accelerate telomere shortening? They might.

This is pure observational study click-bait, courtesy of the American Journal of Epidemiology, the kind of thing corporate journalism loves to trot out. And who can fault them? We clearly aren't the size of the Washington Post, so people like what they like. What isn't noted is that elderly people might be sitting 10 hours a day because they had other issues unrelated to telomeres. That ruins breezy correlation-causation narratives.