1. Stand up against a wall. Make sure your back is flat agains the wall.
2. Place your arms out to the side in one of the positions shown in the figure above. Lightly push against the wall for a number of seconds but keep your back flat against the wall still.
3. You should feel as if the push is coming from the muscles in between your shoulder blades. You shouldn’t feel any pain in your shoulders or tension in the upper traps.
4. Vary the angle of your arms as in the figure above. Changing the angle of the arms will change what muscles you use.
5. Find your maximum arm angle. If you go too high or too low your shoulder position will probably be compromised and the exercise loses benefit and can potentially cause injury.