People don't need the experts to tell them that sitting around too much could give them a sore back or a spare tire. The conventional wisdom, though, is that if you watch your diet and get aerobic exercise at least a few times a week, you'll effectively offset your sedentary time. A growing body of inactivity research, however, suggests that this advice makes scarcely more sense than the notion that you could counter a pack-a-day smoking habit by jogging. "Exercise is not a perfect antidote for sitting," says Marc Hamilton, an inactivity researcher at the Pennington Biomedical Research Center.Is Sitting a Lethal Activity?
The posture of sitting itself probably isn't worse than any other type of daytime physical inactivity, like lying on the couch watching "Wheel of Fortune." But for most of us, when we're awake and not moving, we're sitting. This is your body on chairs: Electrical activity in the muscles drops -- "the muscles go as silent as those of a dead horse," Hamilton says -- leading to a cascade of harmful metabolic effects. Your calorie-burning rate immediately plunges to about one per minute, a third of what it would be if you got up and walked. Insulin effectiveness drops within a single day, and the risk of developing Type 2 diabetes rises. So does the risk of being obese. The enzymes responsible for breaking down lipids and triglycerides -- for "vacuuming up fat out of the bloodstream," as Hamilton puts it -- plunge, which in turn causes the levels of good (HDL) cholesterol to fall.
Mark Frauenfelder is the founder of Boing Boing and the editor-in-chief of MAKE and Cool Tools. Twitter: @frauenfelder. Come and hear Mark speak at the ALA conference in Chicago on July 1.