Association Between Pitch Break on the 4-Seam Fastball and Slider and Shoulder Injury in Major League Baseball Pitchers: A Case-Control Study

The shoulder joint complex in the throwing motion

The shoulder joint complex in the overhead athlete is organized to effectively transfer the proximally generated forces distally into the arm. The organization also protects the joints and anatomic structures against the repetitive high velocities, large ranges of motions, and compressive, shear, translational, and distraction loads in the overhead motion while placing the hand in the "launch window." Coupling of the movements of the scapula, clavicle, and humerus results in scapulohumeral rhythm (SHR). Effective SHR requires the clavicle and scapula-and, at times, the mechanically linked claviscapular segment-to move the arm into the task-specific position and motion and requires the humerus to move through the ranges of motion to achieve the specific task in the throwing motion. Alterations in SHR can negatively affect effective shoulder joint complex function in the overhead throwing motion and increase injury risk. There are 4 phases of clavicular, scapular, and claviscapular motion that are coupled with arm motion in SHR. The first 3 phases occur in arm elevation motions from 0°-90° and result in the claviscapula and humerus being placed in task-specific positions. The fourth phase is coupling of claviscapular motion with humeral motion to maintain ball-and-socket kinematics throughout the throwing motion. Alterations in this composite motion are termed "scapular dyskinesis." The dyskinesis is considered an impairment of the efficient mobility of the claviscapular segment of the shoulder complex. The most prevalent problem with scapular dyskinesis is the association of scapular protraction and consequent glenoid antetilt with alterations in humeral rotation and posterior humeral head translation to produce shoulder joint internal impingement. Task effectiveness in overhead throwing is also based on and determined by humeral range of motion, precision of humeral motion, and velocity of humeral motion, as well as humeral and arm position in 3-dimensional space. This activity requires maximum ball-and-socket kinematics to create the highest amount of concavity-compression that creates stability for the joint. There are bony and soft-tissue contributions to this stability. Injuries to the glenoid labrum are among the most common deficits that alter concavity-compression. Clinical evaluation of the shoulder joint complex in the injured throwing athlete should be comprehensive and systematic, following an evaluation pathway for proximal and distal causative factors and including observation of humeral motion. This type of evaluation can result in intervention protocols that address the pathoanatomic, pathophysiological, and pathomechanical deficits identified.

Pitch release speed predictors for division I collegiate baseball players

BACKGROUND: Analytics, to quantify baseball pitch metrics, take on many forms and are unlike earlier methods to assess performance. OBJECTIVE: Quantify associations of flight kinematic and anthropometric variables on pitch release speed. METHODS: Male college-age pitchers (n= 182) from 2021 Division I games provided data. A 3D radar system collected data. Fixed effects regression OLS models analyzed data for sliders, changeups, curveballs, and fastballs. RESULTS: Spin rate (r= 0.017–0.514, p< 0.05) and vertical break (r= 0.374–0.703, p< 0.05) were positively associated with pitch release speed per pitch type. Release height (r=-0.286–0.051, p<-0.05) and pitch extension (r=-0.176–0.43, p< 0.05) were negatively associated with pitch release speed per pitch type except sliders. Spin axis had a negative association with pitch release speed for fastballs (r=-0.235, p< 0.05) and sliders (r=-0.311, p< 0.05), and a positive association (r= 0.029, p< 0.05) with curveball pitch release speed. Weight only related to pitch release speed for fastballs (r=-0.315, p< 0.05). Height did not impact pitch release speed. CONCLUSIONS: Results refute long-held beliefs of anthropometry’s influence on performance and instead reveal flight kinematics’ impact on baseball pitch release speed.