Yoga may be all the rage at your local gym, but the truth is—it’s old news. Experts can trace the origins of yoga all the way back to 2250 B.C. as the Harrapan civilization in Northern India began to develop postures and breath-control techniques that they hoped would enable them to enter an altered consciousness and access the spirit realm. Today, exercise enthusiasts are flocking to yoga studios and fitness centers in the hopes of reaping more tangible body benefits like improved muscle tone and strength, better balance and, of course, pretzel-like flexibility. “Mind-body exercise” has been the fitness buzzword du jour for at least five years now and, according to recent stats from the Sporting Goods Manufacturers Association, more than 11 million Americans currently practice yoga. Yet despite yoga’s long history and the enormous number of faithful participants, very little real research has been conducted regarding its physical benefits. That’s where the American Council on Exercise comes in. We know anecdotally, and from firsthand experience, that yoga is a valuable fitness activity, but we decided to tap the research experts at the University of Wisconsin, La Crosse, to find out just how effective it really is.