Do Pitching Biomechanics and Shoulder and Elbow Kinetics Differ Between Pitching on 2 Specific Dirt Surface and Turf Surface Mounds?

Rafael F Escamilla; Jonathan S Slowik; Rodney Imamura; Irwin S Thompson; Robert Asuncion; Arnel L Aguinaldo; Glenn S Fleisig

doi:10.1177/23259671251380862

Do Pitching Biomechanics and Shoulder and Elbow Kinetics Differ Between Pitching on 2 Specific Dirt Surface and Turf Surface Mounds?

Orthop J Sports Med. 2025 Nov 26;13(11):23259671251380862. doi: 10.1177/23259671251380862. eCollection 2025 Nov.

Authors

Rafael F Escamilla¹, Jonathan S Slowik², Rodney Imamura³, Irwin S Thompson¹, Robert Asuncion¹, Arnel L Aguinaldo⁴, Glenn S Fleisig²

Affiliations

¹ Department of Physical Therapy, California State University, Sacramento, Sacramento, California, USA.
² American Sports Medicine Institute, Birmingham, Alabama, USA.
³ Kinesiology and Health Science Department, California State University, Sacrcamento, Sacramento, California, USA.
⁴ Department of Kinesiology, Point Loma Nazarene University, San Diego, California, USA.

Abstract

Background: While most baseball fields have dirt pitching mounds, some fields have turf mounds. In addition, portable turf surface mounds are often used for bullpen or practice sessions, off-season training, or when assessing pitching mechanics in a biomechanics laboratory. Pitching on dirt surface mounds permits metal cleats to be worn, which are often discouraged on turf surface mounds because of potential damage to the turf.

Purpose: To assess differences in shoulder and elbow kinetics and pitching kinematics in college pitchers between pitching on a dirt surface mound with metal cleats versus pitching on a turf surface mound with turf shoes.

Study design: Controlled laboratory study.

Methods: A total of 18 college pitchers pitched both on a dirt surface mound and on a turf surface mound. All pitchers were tested using a 240-Hz, 12-camera motion analysis system, and 28 kinematic and 7 kinetic parameters were calculated. Differences in kinematic and kinetic parameters between pitching on dirt surface and turf surface mounds were assessed with paired within-participant t tests employing the Benjamini-Hochberg method to correct for multiple comparisons (adjusted P < .05).

Results: Two kinetic parameters showed significant differences, with maximal elbow varus torque (to resist valgus loading) and maximal shoulder internal rotation torque significantly greater when pitching on a dirt surface mound compared with pitching on a turf surface mound. Maximal lead knee height, elbow flexion, knee flexion, rotational separation between upper trunk and pelvis, maximal shoulder external rotation, and forward trunk tilt were significantly greater when pitching on a dirt surface than on a turf surface. Pelvic drift at maximal lead knee height and arm slot angle were significantly greater pitching on a turf surface than on a dirt surface.

Conclusion: Of the 35 kinematic and kinetic comparisons, 10 of the comparisons (29%) were significantly different between pitching on a dirt surface mound and pitching on a turf surface mound. Kinematic differences only involved body segment and joint positions and not angular velocity magnitudes or timings. Kinetic differences demonstrated that elbow valgus and shoulder loading were slightly greater pitching on a dirt surface with metal cleats compared with pitching on a turf surface with turf shoes.

Clinical relevance: Compared to pitching on a dirt surface mound, pitching on a turf surface mound may decrease joint stress and injury risk for the throwing shoulder and elbow, although differences in kinematics between mounds should also be considered.

Keywords: elbow varus torque; pitching biomechanics; pitching mechanical efficiency; shoulder and elbow injury risk.