Sitting is murder on your posture. And these days we do it more than ever. A 2007 survey by Vanderbilt University's Institute for Medicine and Public Health found that women spend nearly eight hours a day parked on their fannies, often hunched over a keyboard or slumped on the sofa. Womens health "When women do get off the couch, they spend hours working on their 'beach' muscles, like the chest, abs, and quads, and neglect posterior muscles, like the traps, back, hamstrings, and glutes," says trainer and coach Kevin Buckley, owner of Dynamic Strength and Conditioning in Nashua, New Hampshire. The result is muscle imbalance that doesn't just look bad (saggy buns are never pretty) but also prevents your body from operating optimally.