Primary Muscle Group: Core Muscles
Muscle groups worked in this exercise: Rectus Abdominus, Internal and External Obliques.
Preparation: Start by sitting on the ball with your knees bent and feet flat on the floor. Slowly walk your feet forward as you slide your torso down the ball. Your trunk should be parallel to the floor. Just let your hips clear the ball and let your lower back press into the ball; cross your arms over your chest.
Breathing: Exhale as you lift your torso, Inhale when returning to your start point.
Execution: Pull your navel towards your spine and concentrate on contracting your abs as you lift your torso. Lift your upper torso off the ball, remembering to exhale. Inhale as you return to neutral.
Comments: If your neck becomes fatigued, place one or both hands behind your head for support. Remember not to pull up on your neck!
Here are a few suggested alternative exercises:Ab CrunchAb Crunch - MachineAb Crunch ObliquesDouble CrunchDumbbell Side BendsKneeling Cable CrunchKneeling Oblique TwistLateral Bend with Barbell