|This is to stretch out the posterior capsule of the shoulder and to assist with shoulder flexibility, especially into internal rotation/ hand behind back mobility.|
Lie on the side you want to stretch with your head supported. Place the arm in front of you so the elbow is straight in line with the shoulder at 90 degrees. Rock forwards slightly so your shoulder blade is behind you and you are not lying on top of it. Bend the elbow so its at 90 degrees, and use your other hand to start to stretch the arm down towards the floor. When you get to the end of range and feel a stretch, hold for a few seconds, then ease off. Keep working into and out of the range until you start to see an improvement in the range of motion.
This may be a little uncomfortable, so keep the stretch within your comfort limits. Don't push or overstretch if its painful or reproduces your pre-existing shoulder pain.