Ab Workout: 5 Stability Ball Ab Exercises.

Crunch

Sit on the ball and roll out until lower back is resting on ball.

Keep feet shoulder width apart and place hands behind your head.

Raise head even with torso and look straight up.

Return and repeat.

Pike

Position your legs on the ball, keeping your back is straight, and your core is engaged.

Lift your hip upwards, raise your body up.

Slowly lower your body back to the starting position and repeat.

Rollout

Kneel in front of a ball, place your forearms on the ball.

Keeping your back flat,  slowly roll the ball away from you by straightening your arms.

Pause, then bend your elbows to roll the ball back to start. 

Jackknife

Position your legs on the ball, keeping your back is straight, and your core is engaged.

Pull knees toward chest until heels are under or near glutes.

Return by extending hips and knees to original position. Repeat.

Plank

Place your elbows on a Swiss ball. Raise your hips off the ground.

Keeping your core engaged, hold this position for the recommended amount of time.