The Kinetic Chain’s Involvement in the Pitching Motion The scapula acts synchronously with the rotator cuff to maintain the glenohumeral center of rotation within a physiologic range during the pitching motion. This integrated effort relies on the trapezius, rhomboids, levator scapulae, and serratus anterior muscles for stabilization, positioning, and synchronous scapular motion.
26 An intricate relationship between the dynamic stabilizers (rotator cuff, pectoralis major, and latissimus dorsi) and static stabilizers is required to simultaneously supply the range of motion, force, and stability of the glenohumeral joint. 8, 21 Extreme degrees of external rotation of the shoulder, coupled with forward linear trunk motion, allow a greater distance for the accelerating force to be applied to the ball, generating top velocity. 7 Maximum humeral internal rotation velocity during throwing may reach 7500 to 7700 degrees per second. The time elapsed between front foot contact and ball release is only 0.145 seconds, 30 followed by an additional half second for the ball to reach home plate. The extremely rapid rate of this motion makes assessment difficult. Coordinated lower extremity muscles (quadriceps, hamstrings, hip internal and external rotators) provide a stable base for the trunk (core musculature) to rotate and flex. The lower extremity and trunk generate and transfer energy to the upper extremity. The effective synchronous use of selective muscle groups maximizes the efficiency of the kinetic chain ( Table 1).
The overhand pitching motion consists of a sequence of body movements that start when the pitcher lifts the lead foot, progresses to a linked motion in the hips and trunk, and culminates with a ballistic motion of the upper extremity to propel the ball toward home plate.
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