Thank you all for the positive response. Amba, the side wall squat is all about stabilizing the standing leg. It specifically strengthens the Gluteus Medius. Keeping the ball still during the squat, forces the client to move from the pelvis and move the sits bones back to squat. Most of the time they would want to just bend the knees. If they just bend the knees the ball will move. Hope this answered your question.