Shoulder Blades/Scapula plays an important role in your Shoulder Stability. It helps maintains the posture well so that your shoulder is not getting injured. But most of us have an Unstable Shoulder Blade which would actually leads us to Injuries in the Neck and Shoulder. One important factor contributes the Instability is the weakening of the Upper Back muscles. This happens because of 2 reasons. One if you working out your Chest muscles quite a bit,because of that the Shoulder drawn forward so that it weakens the Muscles which maintains the stability of the Shoulder Blade. The other important reason is Long sitting in slouched way. Because of this Your Shoulder drawn forward thus it weakens the Muscles which provides stability of the Shoulder Blades. Over a period of time it leads to posrural changes such as Stoop Back,Rounded Shoulders, Forward Neck and it would actually lead to Muscle Tear in Shoulder. This it is very important to work on the Stability of Shoulder Blade and make them stronger.