Sit on exercise ball. Walk forward on ball and lie back on ball with shoulders and head hanging off. Switch position of feet by positioning bent leg under extended leg so waist is twisted with hip positioned sideways. 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 and repeat. Position legs in opposite position and continue.
Certain individuals may need to keep their neck in neutral position with space between their chin and sternum. Exercise can be performed without added weight until more resistance is needed. Movement can also be made easier by po sitioning hip low on ball or by using no added weight. In contrast, exercise can be made more challenging by positioning hip higher on ball. In which case, feet may be placed against base of wall for stability. Also see Spot Reduction Myth and Arm Position During Waist Exercises.