This abs exercise, created by Nick Tumminello, certified master trainer and owner of Performance University in Fort Lauderdale, Fla., works your entire core, including the muscles in your shoulders, abs, glutes, and back.
Sit in an L-sit position on the floor with your legs together and your hands behind your torso, fingers pointing back. Keep your elbows and knees straight. Squeeze your shoulders and glutes together as you lift your hips up off of the floor (as shown). From here, use your abs to reverse the movement and pull your hips through your arms as far back as possible, without allowing your butt to touch the floor. Once your hips cannot go back any father, slowly lower your butt down to the floor and return to the starting position. That's one rep.