Lying on top of an exercise ball facing towards the floor, extend feet and arms out behind you with chest on the ball.
Maintain a neutral spine and good posture during the lift. Lift off the ball with arms extended out.Exercise of the Week : Cobra on Ball
The prime movers are the rhomboids, lumbar spine and large trapezius.
Be sure to not lift too high off the ball, because this is overuse of the lumbar