Position yourself lying face up on a decline bench (angled at 15-30 degrees) with your head near the knee rolls. Reach both arms backward over your shoulders to take hold of the bench with both hands. This prevents you from sliding down. Once locked into this position, your torso will lay along the bench, you will have a slight bend at the knee and your lower legs will hang off the end. This is the starting position.
Commence the movement by contracting your abdominals and bringing your legs toward your torso by rolling your pelvis upward. Exhale through the movement.
At the top of the contracted position, your hips will be off the bench and you should feel that real squeeze across your abs. Reverse the movement by lowering you torso and hips back to the bench and the starting position, inhaling as you do.