The Well blog at The New York Times summarizes a few new sitting-is-death-related studies in an article published today.
One from the British Journal of Sports Medicine concludes that one of the mechanisms of death that sitting uses is the shortening of our cells’ telomeres. It’s nice to imagine this like a rope, the rope being your DNA: when you sit, someone is taking a knife and slowly whittling away the end of the rope. When you sit less, the rope actually grows. This correlation was directly between sitting and telomere length; exercise amount had no effect.
For most things physiological, I like to imagine them operating in tiny micro-cycles. Many times, this is an easy visualization: every step you take is one micro-cycle of loading in your feet and ankles, and we try to accumulate as many as possible. We can easily view sitting and standing this same way: every second spent sitting is one knife-swipe at your DNA, and every second spent standing sews an extra strand onto that same metaphorical rope. The goal is to make standing a net positive.