Lie face up on floor, knees bent with feet on floor and neck straight. Cross arms over chest. In a controlled motion, keeping neck straight, curl upper body up. Contract abdominals fully without compromising form. While maintaining the controlled motion, return to starting position. Do not allow muscle to relax before next repetition.
Here are a few suggested alternative exercises:Ab Crunch - MachineAb Crunch ObliquesBall CrunchDouble CrunchDumbbell Side BendsKneeling Cable CrunchKneeling Oblique TwistLateral Bend with Barbell