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 while turning your torso to the left. Contract abdominals fully without compromising form. While maintaining the controlled motion, return to starting position. Do not allow muscle to relax before next repetition. After completing one set on the left, switch to your right side. Focus on really twisting your torso and feeling the contraction when you are in the up position.
Here are a few suggested alternative exercises:Ab CrunchAb Crunch ObliquesBall Crunch ObliquesDouble CrunchDumbbell Side BendsKneeling Oblique TwistLateral Bend with Barbell