Prone Shoulder T's
How To: Lay on your stomach with both arms out to the side in a T position, arms are locked out at the elbow & thumbs pointing up. Keep the shoulders down & back, head neutral. Slowly raise the arms off the floor as high as you can without compensating.
Compensations: Watch for raising the chest off the floor, bending the elbows, dropping your head or elevating and rounding the shoulders forward.