Shoulder horizontal abduction prone Lie on your front with your arms by your side and your palms facing downwards. Lift your shoulders, pulling your shoulder blades back and down. Lift your arms slightly off the floor and then move them out to the side and up towards the side of your head in an arch. Slowly return to the start position and relax your arms, then repeat. Note, a weight can be added to your arms to increase the difficulty of this exercise. 1. Increases Functional Internal Rotation