Jonathan Ross, an ACE-certified fitness expert and author of Abs Revealed, created this dynamic move that uses a stability ball and rapid upper-body movement to seriously engage your abs.
Lie with your hips and lower- and middle-back in contact with a Swiss ball (your head and shoulders extended off the ball). Your feet should be flat on the floor. Raise your head and shoulders and crunch your ribcage toward your pelvis, reaching both arms up to the ceiling. Hold for 1 count. As you lower out of your crunch, whip your arms down and around to the right in a fast circular motion, coming all the way back up to the top of a crunch, reaching your arms up at the top of your circle. Do 8-10 reps to the right, and then 8-10 reps circling to the left.