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Role of Rotational Kinematics in Minimizing Elbow Varus Torques for Professional Versus High School Pitchers
Journal article   Open access   Peer reviewed

Role of Rotational Kinematics in Minimizing Elbow Varus Torques for Professional Versus High School Pitchers

Micheal J. Luera, Brittany Dowling, Mitchel A. Magrini, Tyler W. D. Muddle, Ryan J. Colquhoun and Nathaniel D. M. Jenkins
Orthopaedic journal of sports medicine, Vol.6(3), pp.2325967118760780-2325967118760780
03/20/2018
DOI: 10.1177/2325967118760780
PMCID: PMC5863871
PMID: 29581995
url
https://doi.org/10.1177/2325967118760780View
Published (Version of record) Open Access

Abstract

Background: Elbow injury rates among baseball pitchers are rapidly rising. However, this increase has been most dramatic among high school (HS) pitchers. Purpose: To examine pitch velocity and the kinetic and kinematic characteristics of HS versus professional (PRO) pitchers to identify potential differences that may play a role in the increased risk of ulnar collateral ligament injury in youth pitchers. Study Design: Controlled laboratory study. Methods: A total of 37 HS (mean SD: age, 16 1 years) and 40 PRO (age, 21 2 years) baseball pitchers completed maximal-effort baseball pitches during a single testing session, from which pitch velocity (PV), absolute and normalized elbow varus torque (EVTA and EVTN, respectively) during arm cocking and at maximum shoulder external rotation (MER), and 8 other elbow and shoulder torques or forces and rotational kinematics of the pelvis and trunk were analyzed, recorded, and compared. Results: PV was greater in PRO than HS athletes; EVTA was greater in PRO than HS athletes during arm cocking and at MER; but EVTN was similar during arm cocking and greater in HS than PRO athletes at MER. In PRO athletes, PV was not related to EVTA during arm cocking or MER (r = 0.01-0.05). Furthermore, in PRO athletes, EVTA during arm cocking and at MER were inversely related to upper trunk rotation at hand separation and foot contact and to pelvis rotation at elbow extension (r = -0.30 to -0.33). In contrast, in HS athletes, PV was strongly related to EVTA during arm cocking and MER (r = 0.76-0.77). Furthermore, in HS athletes, PV and EVTA during arm cocking and at MER were moderately or strongly related to the other elbow and shoulder torques and forces (r = 0.424-0.991), and EVTA was not related to upper trunk rotation or pelvis rotation throughout the throwing motion (r = -0.16 to 0.15). Conclusion: The kinetic and rotational kinematic differences observed between PRO and HS pitchers in this study may help explain the greater performance of PRO pitchers while allowing them to minimize EVT during pitching. HS pitchers, however, do not appear to be as capable of utilizing the forces generated by rotation of their trunk and pelvis to aid in pitching, and those who throw the hardest generate the greatest forces at the shoulder and elbow. As a result, they experience higher EVTs relative to their body size, which may place them at an increased risk of injury.
 Life Sciences & Biomedicine Orthopedics Science & Technology Sport Sciences

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