HOW: For this exercise, find a stable surface such as a squat rack or a doorway. Begin with your elbow bent and your body facing the doorway. Place the inside of your wrist against that surface and rotate your body away from your wrist putting your shoulder into external rotation. From this position, lift your hand off of the doorway holding for the prescribed amount of time.
FEEL: You will feel the muscles in your shoulder working as well as the muscles around the shoulder blade working.
COMPENSATION: Avoid straightening your elbow as you perform this exercise. You want to be sure the motion is coming from your shoulder joint and not the elbow joint.