The Role of Shoulder Posture in Pitching Mechanics in High School Baseball Pitchers

Although compromised shoulder posture impacts scapular biomechanics, the interplay between shoulder posture and scapular biomechanics during the dynamic pitching motion in high school baseball pitchers remains unexplored.

To characterize the shoulder postures of baseball pitchers and investigate their relationships with scapular biomechanics during pitching.

Descriptive exploratory study.

Laboratory.

Thirty-eight high school baseball pitchers (age = 16.9 ± 0.9 years).

Shoulder posture was determined by acromial distance (AD), pectoralis minor index (PMI), scapular index (SI), and forward shoulder angle (FSA) in the dominant arm. The scapular kinematics and associated muscle activation (upper trapezius [UT], serratus anterior [SA], lower trapezius, biceps brachii [BB], triceps brachii [TB], anterior deltoid) during pitching were recorded.

There was a moderate-to-strong negative correlation between AD and upward rotation (r = -0.47 to -0.55, P < .01) and a moderate negative correlation between AD and posterior tilt (r = -0.40 to -0.44, P < .01). Pectoralis minor index and FSA also showed moderate positive correlations with posterior tilt (PMI, r = 0.37, P < .05; FSA, r = 0.34-0.42, P < .04). Acromial distance had moderate-to-strong positive correlations with UT, SA, BB, TB, and anterior deltoid activation (r = 0.36 to 0.59, P < .03), whereas SI showed moderate negative correlations with UT, BB, and anterior deltoid activation (r = -0.33 to -0.40, P < .05). Forward shoulder angle displayed a moderate negative correlation with SA and BB activation (r = -0.32 to -0.40, P < .05).

Shoulder posture has significant moderate-to-strong correlations with scapular biomechanics during pitching in high school baseball pitchers. These findings provide a foundation for future research on optimizing shoulder posture to enhance efficient scapular movement patterns. Incorporating posture assessments into routine screenings may allow practitioners to gather valuable biomechanical insights without the need for extensive motion-capture systems.