OBJECTIVES: To compare lower extremity mechanics and energy absorption during two types of landing after a successful or unsuccessful block in volleyball and assess the risks of anterior cruciate ligament (ACL) injury. DESIGN: Cohort study. SUBJECTS: Fourteen elite male volleyball players (aged 24.5 ± 4.6 years; height 1.94 ± 0.06 m; mass 86.6 ± 7.6 kg). INTERVENTIONS: Subjects were required to land on force platforms using stick landing or step-back landing (with the right lower extremity stepping back away from the net) techniques after performing a standing block jump movement. MAIN OUTCOME MEASURES: Vertical ground reaction force (body weight); knee flexion (degrees); knee moments (Nm/kg); and hip, knee and ankle energy absorption (J/kg). RESULTS: The right lower extremity showed a greater first peak of vertical ground reaction force, a greater valgus moment, lower energy absorption by the knee, and higher energy absorption by the hip and ankle joints during step-back landing. CONCLUSIONS: The lower extremity may be exposed to a greater risk of ACL injury when stepping back from the net during the initial impact phase after a step-back landing.

Biomechanics Laboratory University of Massachusetts Amherst MA USA

Human Motion Diagnostic Center University of Ostrava Varenska 40A 70200 Ostrava Czech Republic

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Children's Single-Leg Landing Movement Capability Analysis According to the Type of Sport Practiced