The Jivamukti Yoga Center (404 Lafayette Street; 353-0214) may be famous for its celebrity-client roster, but you don't have to be Sting to enjoy its "psychophysical" sessions -- now copied citywide. And while newcomers may be confused by the quick succession of poses, they will sweat. High-impact junkies may scoff at the idea -- but at least believe the body of Christy Turlington, who says she appreciates the teacher's "commitment." Power-yoga fans threatened by supermodels and their superbodies tend to congregate at the Yoga Zone (160 East 56th Street, twelfth floor; 935-9642).