It's time to revisit the adage proximal stability promotes distal mobility. This should be a prehab prerequisite to any strenuous overhead exercise. Demonstrated here is a dynamic mobility and stability drill for anterior scapulae muscles. What good is all the mobility in the world if you don't have the motor control and stability to control it?! What's important to appreciate and recognize is this is different than just moving your arm freely in these directions. I am applying a CONSTANT ISOMETRIC FORCE by pressing my hand into the wall as I move the slider. This external cue of 'push into the wall' recruits the anterior scapulae musculature (eg serratus anterior and pec minor muscles) to be active and provide scapular stability.
The particular sequence of scapulae movements I'm demonstrating is as follows: 1) protraction and upward rotation, 2) protraction, 3) protraction, downward rotation, and depression, 4) protraction, upward rotation, and elevation. In summary, we are working shoulder blade mobility and stability in all directions!
It is important to note performing closed chained exercises similar to this (hand on wall) increases activity of the rotator cuff muscles. Increased activity of these muscles = dynamic stability of the shoulder. Proximal stability of the shoulder facilitates optimal distal mobility!