Physioball Russian Twist Position

Physioball underneath shoulder blades with hips pushed to sky and hands pointing straight up in the air
Procedure

Keeping hips still, rotate shoulders and trunk to the right, rolling the ball underneath right shoulder
Return to start position and repeat to other side
Repeat for prescribed number of repetitions
Coaching Keys

Keep hips pushed to sky- do not let them drop during movement
Keep stomach tight

You Should Feel It
In trunk and hips

You can all do this with a medicine ball to increase the difficulty.