This video demonstrates a tornado ball rotation while bridging on a swiss ball. Dynamic stabilization of the entire torso; the abdominals AND posterior chain. The lifter has to bridge and remain parallel to the floor throughout the movement and remain fixed while the tornado ball is rotating.
If you do not have a tornado ball, a med ball in a sandbag/dufflebag/pillow case can be used.
The great thing about this exercise is that the lifter is isometrically contracting the anterior and posterior chains against a dynamic, ever changing tension. This increases the frequency AND intensity of the motor unit recruitment which is exponentially more beneficial than a static, long duration contraction. Not only that, there is also a deceleration and acceleration component to the lift as well.
Think interval training rather than slow, low intensity treadmill.
Also, this version is easier on the shoulders than the standard swinging overhead version of the tornado ball.
Oh yeah, the video is a LITTLE FOGGY :). We were in the middle of a conditioning circuit and the camera guy was heated!