Side plank on stability ball, elbow on wobble cushion trunk rotation ("Plank, side on-the-ball" Core/scapular stabilization, with trunk rotation, arm on wobble cushion, legs on stability ball)

Lie on your side with your legs on a stability ball.
Place your forearm on the floor with your elbow on a wobble cushion.
Lift your hips up into the plank position.
The closer the ball is towards your feet, the harder the exercise will be.
Holding this position, lift your upper arm into the air, then reach it under your body, rotating your trunk as you do so.
Ensure you do not drop your hips to the floor or bend your back too much.