Resisted shoulder external rotation standing (Shoulder external rotation strengthening, with band, arm at side, standing; 02)

Stand holding a resistance band in one hand.
Have an assistant holding the other end of the band on your other side.
Keep your upper arm close to your side and the elbow at a right angle.
Stretch the band by turning your arm outwards.
Make sure your body stays still and your wrist stays in neutral position.
Control the movement as you bring your arm back in towards your tummy.