A Biomechanical Analysis of Lead Hip Flexion in Professional Baseball Pitchers

Deficits in passive range of motion (ROM) and strength of the lead hip during the pitch among professional baseball pitchers are associated with increased injury risk to the core, groin, and throwing shoulder.

A positive, linear relationship will link lead hip flexion at maximum shoulder external rotation (MER) with pitch velocity.

Descriptive laboratory study.

Level 3.

Professional pitchers were divided into Low (<85°, n = 122), Moderate (85-95°, n = 137), and High (>95°, n = 80) groups based on lead hip flexion at MER, and pitched fastballs while using 3-dimensional motion capture (480 Hz).

Pitchers in the Low, Moderate, and High groups did not significantly differ in age (P = 0.16), weight (P = 0.08), height (P = 0.36), or throwing hand (P = 0.54). Low pitchers had significantly less MER compared with High pitchers (P = 0.04); shorter stride length than Moderate and High pitchers (P < 0.001); greater lead knee extension velocity than High pitchers (P = 0.007); and less lead knee flexion at ball release than Moderate and High pitchers (P < 0.001). Low pitchers had greater shoulder anterior force, elbow anterior force, and elbow flexion torque compared with Moderate pitchers. Lead hip flexion at MER was not predictive in group (P = 0.89) or univariate analysis (P = 0.43) for ball velocity.

This study provides normative values for lead hip flexion angles throughout the pitch. Pitchers with moderate lead hip flexion at MER demonstrated significantly less shoulder anterior force, elbow anterior force, and elbow flexion torque compared with other groups, with no significant relationship with biomechanical efficiency or ball velocity.

Pitchers appear to benefit from maintaining lead hip flexion within an appropriate range at MER, near 90°, as either too much or too little can be disadventagous.