Band External Rotation

Attach a resistance band to a stable anchor point at waist height.
Stand sideways to the anchor and grasp the band with the hand furthest from it.
Bend your elbow to 90 degrees and keep it tucked firmly against your side. You can place a rolled-up towel between your elbow and ribs to ensure proper form.
Rotate your forearm outward away from your body as far as comfortable while keeping the elbow fixed at your side.
Squeeze your shoulder blade toward the spine at the end of the movement.
Slowly return to the starting position under control.