- Lie on the ball, positioning it under the lower back.
- Cross your arms over the chest or place them behind your head.
- Contract your abs to lift your torso off the ball, pulling the bottom of your ribcage down toward your hips.
- As you curl up, keep the ball stable (i.e., the ball shouldn't roll).
- Lower back down, getting a stretch in the abs, and repeat for 1-3 sets of 12-16 reps.
An exercise ball is an excellent tool to strengthen the abs. It's much more effective than floor crunches because the legs tend to be more involved when you're on the floor. When you're on the ball, the abs do more work.
View this exercise in the Best Ab Workout.
Next: Vertical Leg Crunch