Sit on exercise ball. Walk forward on ball and lie back on ball with shoulders and head hanging off, and knees and hips bent. Gently hyperextend back to contour of ball. Hold plate behind neck or on chest with both hands or use no weight.
Flex waist to raise upper torso. Return to original position. Repeat.
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. Also Spot Reduction Myth.
Movement can be made by crossing arms on chest. Movement can also be made easier by positioning hips low on ball.
Exercise can be made more challenging by placing hands further up on or beyond head. See Arm Position During Waist Exercises. Exercise can also be made more challenging by positioning ball lower on back and hips higher. Exercise can also be performed on incline board or with additional weight.