HOW: Begin by lying on your back with knees bent, feet flat on the floor. Take the knees of both legs towards the chest and the hands of both arms towards the feet. Using a Swissball, connect the hands and the knees for a static hold. Using your hands and the ball as resistance, pull the knees towards the chest pushing into the ball slightly.
FEEL: You should feel your front and side abdominals. You should feel the front of both hips as they push into the ball
COMPENSATION: Avoid letting the shins sag down towards the floor. Avoid overextending your low back by maintaining a neutral pelvic position and not arching your back.