Shoulder internal and external rotation supine with weight (Bilateral)

Lie on your back with your arms stretched out at approximately 90 degrees from the side of your body holding onto a weight on each hand.
Bend your elbows to a right angle and then slowly rotate your forearm up and then lower it back down, keeping control of the weight.
Make sure your shoulder blades remain in contact with the floor throughout the movement.
Relax and repeat.