Swiss Ball Jackknife Rotation

Brace your abs. Put your elbows on the bench and rest your shins on the stability ball. With your arms straight and your back flat, your body should form a straight line from your shoulders to your ankles. Keeping your back straight, roll the ball to your chest and bring your knees to one side of your body by contracting your abs and pulling the ball forward. Pause and then return the ball to the starting position by rolling it backward. Alternate sides.