Starting Position: Sit on the stability ball with your feet flat on the floor. Slowly begin walking your feet forward as you tuck your tail under. Lower your spine onto the ball as you walk your feet away from the ball. Continue lowering until your shoulders, back and tailbone are resting on the ball. Feet should be parallel and shoulder width apart. Knees are bent to about 90 degrees. Distribute your weight evenly through your feet. Your mid-back should be positioned on the top of the ball (at 12 o'clock) and your hips should be positioned at 2 o'clock.
Place your hands behind your head, squeezing your shoulder blades together and pulling your elbows back without arching your low back. This elbow position should be maintained throughout the exercise. Keep your head aligned with your spine, but allow your chin to tuck slightly during the upward phase of the exercise.
Upward Phase: Exhale. Engage your abdominal and core muscles. Tuck your chin slightly toward your chest and slowly curl your torso toward your thighs. Since the abdominal muscles attach the rib cage to the pelvis, your movement should focus on pulling these two body parts closer together. Try to keep the neck relaxed. Your feet should be firmly planted, and your tailbone and lower back should remain in contact with the ball at all times. Continue to curl up until your upper back is off the ball. Hold this position briefly while maintaining your balance.
Downward Phase: Gently inhale and slowly uncurl, lowering your spine back towards the ball in a controlled fashion. The feet are planted, and your tailbone and low back stay connected to the ball.
Should balance prove to be a challenge, widen your base of support by moving your feet apart. As you improve your balance skills, increase the balance challenge of this exercise by reducing your base of support and moving your feet together.