Exercise Science Corner – Influence of Throwing Kinematics on Ulnar Collateral Ligament Thickness in Collegiate Baseball Players

May 6th, 2025 | Lawrence, KS, USA

Link to this article can be found here

Background:

The extent to which differences in throwing kinematics between pitchers and nonpitchers influence ulnar collateral ligament (UCL) thickness has yet to be explored.

Purpose:

To examine bilateral UCL thickness in collegiate baseball players and potential contributions of throwing mechanics to the throwing arm’s UCL over the course of a preseason.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

A total of 22 Division I collegiate baseball players (pitchers: n = 11; nonpitchers: n = 11) from one university participated in this investigation. Ultrasound was used to measure UCL thickness in both the throwing and nonthrowing arms. Players wore a throwing sensor during all throwing activities that recorded elbow varus torque, arm speed, shoulder rotation, and arm slot. A 2-way analysis of variance (position [pitcher vs nonpitcher] × arm [throwing vs nonthrowing]) was conducted to investigate UCL thickness. Independent-samples t tests were used to compare throws between pitchers and nonpitchers. Pearson correlation coefficients were used to analyze relationships between UCL thickness and throwing variables.

Results:

UCL thickness was significantly greater in the throwing arm versus nonthrowing arm (0.618 ± 0.038 vs 0.581 ± 0.047 mm, respectively; P ≤ .001) and was significantly greater in pitchers than nonpitchers (0.618 ± 0.039 vs 0.581 ± 0.045 mm, respectively; P = .03). A significantly greater throw count (P = .02), high-effort throw count (P ≤ .001), torque (P ≤ .001), and high-effort torque (P ≤ .001) were observed in pitchers. UCL thickness was significantly related to high-effort throws (r = 0.43), torque (r = 0.42), high-effort torque (r = 0.48), and arm speed (r = 0.46).

Conclusion:

The findings emphasize the unique biomechanical demands on pitchers, highlighting the necessity for targeted injury monitoring strategies in baseball, particularly focusing on high-effort pitches.

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