This exercise challenges all of the core muscles to stabilize the body on the ball, while using the obliques to rotate the body, above the waist, to either the left or right. Keeping the posture aligned and using the Exhale to cause the body to rotate while the rest of the body, that below the waist, remains stable, keeping the majority of the weight on the ball, not on the legs. Find our more at www.susannaengfitness.com/.