HOW: Grab onto a bar with your arms slightly spread apart. Then shrug your shoulder blades up and back simultaneously. You can an option to slightly hinge at the hips to allow for a better angle of pulling the shoulder blades back.
FEEL: You will feel the muscles on the top and back of your shoulders working with this exercise, particularly the upper traps.
COMPENSATION: Keep your arms slightly out from your side to achieve the 30 degrees of abduction, don’t have them right at your side.