The Relationship of Shoulder and Elbow Stresses and Upper Limb Contact Order During a Round-Off Back Handspring.

Introduction: Despite high injury incidence rates in gymnastics, there is a paucity of data characterizing upper extremity injury causation and biomechanical risk factors. This study investigated contact forces across multiple joints in both upper extremities during a round-off back handspring (ROBHS), a fundamental gymnastics tumbling maneuver. Objective: (1) To characterize the three-dimensional (3-D) biomechanics of the sequential, asynchronous contact of each upper extremity with the ground during a ROBHS using 3-D motion capture, and (2) to evaluate potential correlations to upper extremity injury risk. Design: Observational cross-sectional study. Setting: Controlled laboratory environment. Participants: Fourteen competitive female gymnasts aged 10-21 years (mean age: 16.6 ± 3.1 years) (1) participating on a competitive gymnastics team; (2) capable of successfully completing a ROBHS; and (3) free of reported injury at enrollment. Interventions: Not applicable. Main Outcome Measures: Variables evaluated include joint angle, torque, compression force, ground reaction force (GRF), time to peak GRF, and limb loading rates. Variables were analyzed at the wrist, elbow, and shoulder of both limbs at ground contact. The hypothesis that these dependent variables would differ by ROBHS upper extremity contact order was formulated retrospectively after data collection. Results: The first contact limb experienced significantly greater extension torque at the elbow (first: 48.89 ± 18.01 Nm, second: 22.49 ± 9.19 Nm; P = .014; CI 95% [14.83, 37.97]) and faster time to peak GRF (P < .001, CI 95% [-1.79, -0.99]). The second limb of contact experienced significantly greater abduction torque at the shoulder (P = .007; CI 95% [-21.58,-8.08]) and anterior-posterior GRF at contact (P = .007; CI 95% [-1.06,-0.26]). Conclusions: The biomechanical differences between contact limbs during the ROBHS may lead to different injury risk. Recognition of the stresses at the elbow and shoulder for both limbs also provides new insight for rehabilitation clinicians to consider when guiding patients to return to gymnastics activity after injury. [ABSTRACT FROM AUTHOR]

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