Lie on an inclined, flat, or declined bench with your back flat and the sacrum pressed firmly down. Place your legs on a chair or brace the feet against a wall to create a 45-90 degree angle between your trunk and legs. Spread the legs apart so that your feet are pointed out at about two o’clock and 10 o’clock. Cross your arms over the chest.
Contract your abdominals. Begin pulling your rib cage up and toward your pelvis, attempting to move only one vertebra at a time. Continue to your rib cage up and toward your pelvis until your abdominals are fully contracted, keeping the sacrum pressed against the pad. Hold, continue to contract your abdominals, and breath out any remaining air. Slowly lower your trunk one vertebra at a time back to its original starting position, never releasing the tension from your abdominals. Repeat.