Effects of Sport Specialization on Pitching Biomechanics in Adolescent Baseball Pitchers

Abstract

Background:

Adolescent sport culture is moving away from multisport participation, emphasizing sport specialization for improved skill development despite concern of injury. This study examined biomechanical differences among low-, moderate-, and high-level specialized pitchers.

Hypothesis:

Kinetics, kinematics, and peak velocities will vary with specialization level.

Study Design:

Descriptive laboratory study.

Level of Evidence:

Level 3.

Methods:

Adolescent male baseball pitchers’ (N = 46) pain, injury, baseball exposure history, and pitching biomechanics were measured during a single pitching session. Means and standard deviations were calculated for all metrics (significance, P ≤ 0.05) and compared among low-, moderate-, and high-level specialization groups.

Results:

Stride length increased significantly (P = 0.03) from low- (mean, 74% height; SD, 13.6; 95% CI, 64.3-83.8) to high-level (mean, 92.9% height; SD, 6.3; 95% CI, 79.7-86.1) specialization. Hip-shoulder separation at foot contact increased significantly (P = 0.01), with low-, moderate-, and high-level specialization demonstrating means of 21.9° (SD, 12.1; 95% CI, 13.3-30.6), 31.1° (SD, 7.0; 95% CI, 27.7-34.4) and 30.0° (SD, 5.3; 95% CI, 27.3-32.8), respectively. Maximum torso rotation velocity and maximum shoulder internal rotation (IR) velocity increased significantly (P = 0.03) from low- to high-level specialization rising from 930.5 deg/s (SD, 68.4) to 1020.0 deg/s (SD, 75.7), and from 4284.2 deg/s (SD, 311.6) to 4827 deg/s (SD, 512.2), respectively. Peak shoulder distraction force also increased significantly from low- to high-level specialization (P = 0.03), rising from 0.81 N (% bodyweight) (SD, 0.13; 95% CI, 0.72-0.91) to 0.96 N (% bodyweight) (SD, 0.12; 95% CI, 0.89-1.02). There were no significant differences among age, height, weight, or pitch speed across pitching specialization level.

Conclusion:

Differences in pitching biomechanics were observed among low-, moderate-, and high-level specialized high school baseball pitchers.

Clinical Relevance:

Recognizing the impact of sport specialization and negative influences on pitching biomechanics will contribute positively to performance training and injury prevention strategies.