Chasing Stronger, Defined Abs?

ABS - Reverse Crunch

Take position with your back flat on the ground and your arms extended outward at the sides of the body. Keep your feet together and pull your upper legs up so they are perpendicular to your body. Then create a 90 degree angle at the knee so that your lower legs are parallel to the floor. This is the starting position.
Commence the movement by contracting your abdominals and inhaling as you lift your hips off the floor and roll your pelvis backward. As you lift your body, your upper back and shoulders should remain in contact with the floor.
At the top of the movement, your knees approach your chest and you squeeze the abs hard before slowly lowering the body back to the starting position, exhaling as you do.