HOW: Begin by lying on your back with your knees bent and feet off the ground.. Position a band at the wrists. Squeeze a ball or yoga block between the thighs if that assists with appropriate hip positioning. With the elbows to the side, begin by pushing out into the band driving the shoulders into external rotation. Hold the tension while reaching up above your head. Once the elbows are in the plane of the ears, begin to return back to the ground keeping resistance on the band for the entirety of the motion.
FEEL: You should feel the outside of the shoulders working at the rotator cuff. You should feel the inner bottom shoulder blades working at the lower trapezius.
COMPENSATION: Avoid shrugging the shoulders. Avoid letting the wrists come in and avoid straightening the elbows completely as you bring your arms overhead.