Doing crunches on a ball is so much more effective than doing them on the floor.
- Sit on the ball. Place your hands behind your head, and walk your feet away, resting your middle back (not your upper back) on the ball. Keep the knees bent at right angles.
- Exhale and lift your upper body by about 45 degrees, pulling the deep abs in toward the spine, and inhale to return to lower to the starting position.
- Complete three sets of 15 to 20 reps.