Lie on your back and flatten your shoulder blades against the bed.
Whilst keeping your shoulder blades still, have an assistant slowly lift your weaker arm off of the surface, leading the movement with your thumb.
The assistant should help by placing one hand around your wrist and one hand around your shoulder blade.
Keep your elbow straight and point your arm straight up towards the ceiling.
Keep your back and head in contact with the bed and reach your hand up towards the ceiling.
Your assistant should gently facilitate this, ensuring they do not pull your arm up.
Your shoulder will move away from the bed a little.
Hold this position before returning your shoulder blade to the bed.
The movement should come only from your shoulder blade so do not allow your body to rotate.
