Sit on stability ball against low pulley column. Roll back away from low pulley column, so back is on ball. Reach back and grasp cable rope attachment with both hands and place inside of wrists on sides of head. Allow weight to hyperextend lower back against stability ball.
With hips stationary, flex waist so elbows travel toward thighs. Return and repeat.
See Spot Reduction Myth. Certain individuals may need to keep their neck in neutral position with space between their chin and sternum. Some individuals may experience low back discomfort if hips are not bent so they must use smaller ball size or lower their hip position on ball.