A

Lie faceup on a stability ball with your back completely supported and head, neck and shoulders off one end of the ball, torso parallel to ground, feet flat on ground, knees bent and aligned over ankles. Tighten buttocks muscles to stabilize torso and place hands behind head, fingers unclasped.

B

Exhale as you curl torso upward, bringing hips and ribs toward each other, keeping chin level. Slowly lower to starting position and repeat.