Isometric shoulder external rotation in neutral (Shoulder external rotation strengthening isometric, arm at side, supine)

Lie flat on your back with your affected arm on a pillow by your side.
Bend your elbow to a right angle with your fingers pointing to the ceiling.
Place your other hand on the outside of your affected wrist or forearm.
Push outwards with the affected hand with half your maximum effort, using the other hand to resist the movement. Your good hand must be on the affected wrist and not on the hand.
Hold and then relax.