This exercise provided courtesy of Billy Polson, founder and co-owner of DIAKADI Body training gym, voted best personal training gym in San Francisco by CitySearch in 2006.

Benefits
With the constant strain of keeping us upright and supporting the upper body, the lower back is one of the most injury-prone portions of the human body. It's both susceptible to athletic injury and to sedentary injury—problems caused by sitting in a chair too many hours each day. Stability ball hyper back extensions help address this high-risk area by strengthening the lower back without putting high-weight pressure on it.

Muscles Worked
Lower back

Starting Position
Lie face down on a stability ball with your hands shoulder-width apart on the floor in front of you and your legs hanging off the back of the ball and supported by your toes. (see Photo 1).

Exercise

1. From the starting position, lift your legs up from the floor using your lower back muscles. Raise your legs up until your body is completely flat while keeping your stomach on the stability ball and maintaining your balance (see Photos 2 and 3).
2. When your body reaches a flat plank position (do not over-arch your back at the top of the motion), reverse the motion and bring your legs back down to starting position (see Photos 4 and 5).