Ready, hep! That's trapeze-talk for "Let go." You'll learn that and so much more—like what it's like to have your feet flip over your head while flying through midair—at the Espana/Streb Trapeze Academy at SLAM (Streb Lab for Action Mechanics). Choreographer Elizabeth Streb joined forces with a sixth-generation circus family to create the ultimate training ground for her gravity-defying dancers, and since 2005, trapeze pros from the circus world have been using it to teach extreme acrobatics to daring amateurs. If you've never touched a trapeze before, start with an open-level two-hour class, in which you practice hanging upside-down from your knees on a bar eight feet off the ground. After that, it's time for takeoff, which begins on an 18-foot platform. Next comes the backflip, and finally—hep—catches. Don't sell yourself short—the academy reports an 80 to 90 percent first-time catch rate (and 100 percent safety). This is no place for vertigo, but if such heights get you weak in the knees, Espana/Streb also offers trampoline classes, which is actually a great cardio workout and much closer to the ground.