Shoulder Function & Range Of Motion
Every joint in the human body is designed to work within a specific range of motion. For example, when the elbow extends too far we call it 'hyperextension.' The shoulder has greater range of motion than any other joint and this range of movement is made possible by relationships of the shoulder blade's shallow socket and the upper arm ball to the muscles, ligaments, and other soft tissues of the shoulder girdle.
In reality the shoulder girdle is made up of more than one joint (click here for more detail). The shoulder girdle is held at a fixed distance from the sternum (breastbone) by the collarbone and is connected to the shoulder blade at the collarbone's outer end by a ligament. Because of the way it's suspended, the entire shoulder girdle literally floats up and down, forward and backward around the rib cage. One consequence of this extreme range of movement is an inherent lack of stability.
Injury to any one of the four shoulder joints or associated muscles and ligaments results in impaired shoulder function and/or pain. Key point: the ligaments that connect the upper arm and shoulder blade (what we commonly think of as the shoulder joint) are relatively loose and function to restrict range of motion. The way we historically teach baseball pitching and throwing skills encourages athletes to constantly push the limits of the shoulder beyond normal range of motion. Result: damage to ligaments or connective tissue and then, when the shoulder is unstable, damage to structures like the labrum or muscle tendons.
In general, muscles not only move bones centered around joints, but these same muscles also end up protecting joints by limiting the total range of motion. Achieving peak performance during baseball pitching and throwing requires optimal balance between shoulder joint mobility and stability. Throwing athletes (especially baseball pitchers) tend to develop greater shoulder external rotation in their dominant shoulder while simultaneously losing shoulder internal rotation, contributing to functional instability and risk of throwing or pitching injury.
RPM™ injury prevention strategies focus on improving shoulder stability and on changing how force is applied to the shoulder, keeping the range of motion within normal limits.
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