The overhead baseball pitch is an incredible demonstration of the power transmitted through the kinetic chain, generated in the lower extremity and transferred through the upper extremity (Chalmers et al., 2017). Specifically looking at the upper extremity, the overhead baseball pitch is an open kinetic chain movement (Findley & Brown, 1999). The open kinetic chain (OCK) movement does not have a fixed distal segment, enabling free movement that is not fixed to an object (Prokopy et al., 2008). It's important to note that the OKC movements can be associated with closed chain movements, which is demonstrated in the overhand baseball pitch when the forces are generated in the lower extremity before transferring up the kinetic chain to the upper extremity (Findley & Brown, 1999).
To identify the common compensations seen during the overhead pitch, one must have a general understanding of the pitching phases and how they help one to analyze muscle activity and joint actions occurring within each phase. Researchers who study the overhead pitch will use specific tools to measure kinetic, kinematics, and electromyography (EMG) during each pitch phase, allowing them to understand better what muscles are active during the phases (Escamilla & Andrews, 2009). The six phases that describe the pitching motion are wind-up, stride, arm cocking, arm acceleration, arm deceleration, and follow-through (Chalmers et al., 2017).
During the wind-up phase, the pitcher puts himself in a balanced position, which is critical for preparing force generation. Hands are together at the chest, and the lead leg is raised (Chalmers et al., 2017). Injuries are low during this phase; however, as noted by Seroyer et al. (2020), if the pitcher alters his center of gravity by initiating the movement prematurely, the force generated through the kinetic chain will be altered, resulting in significant stress at the glenohumeral and elbow joint to propel the ball forward at top speed.
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