Electromyographic (EMG) studies have determined the peak muscle activity in the Cocking, Acceleration, and Deceleration Phases of the throwing motion required to center the shoulder in the socket.
Scapulothoracic positioning during each of these phases is of paramount importance and is a multifaceted evaluation process. Mobility of the scapula around the rib cage must be assessed actively and passively in isolation and in the required position correlated with the throwing motion. The body will always follow the path of least resistance and watching how the scapula moves in neutral positions and during the endrange stressful times of the throwing motion can illuminate differences that can contribute to the effectiveness in the application of corrective exercises.
The role of the scapula during the cocking and acceleration phase is to seat the humerus in the socket and glenoid fossa to maximize congruency and prepare the RTC for the violent transitions from eccentric to concentric and back to eccentric muscle contractions of the throwing motion. Proper position and mobility of the scapula on the rib cage allows the scapular stabilization musculature to be efficiently utilized and the force couples required for gh mobility to function correctly. The distance that the ball travels during these two phases is important for preparation for efficient and safe delivery and is a product of teaching and physical limitation. If the scapula does not have the required mobility or stability there will automatically be a breakdown in the RTC and its ability to centralize the humeral head which will lead to overuse of one or more of the RTC muscles and could lead to injury. The entire throwing motion is open chain and this must be the determining factor in our evaluation and application of exercise.
The delivery and early deceleration phases of the throwing motion are the two phases where injuries to the RTC occur secondary to the extreme torques and endrange positions that the humerus is forced to endure.
Maximal external and internal rotation are necessary to accelerate the ball at high speed. Each of these endrange positions has arthrological and ligamentous implications. The humerus shifts in the socket and the position of the humerus affects ligamentous and capsular orientation that can either lead to excessive traction or compression of the internal structures depending on the dynamic strength or integrity of the RTC and the position of the scapula. Over time, this process leads to mechanical breakdown from abrasion, compression, or traction. Watching athletes perform exercise with scapular and RTC activity can illuminate excessive gh hyper or hypo mobility. As an athlete you need to be in the hands of someone who understands the implications of corrective exercise. At the OAI we show you how to eliminate passive gh positional faults and how to dynamically stabilize the humerus in the socket and protect you from injury.