Trunk and Lower Limb Muscle Contributions to ACL Loading During Single-Leg Landing
Trunk and Lower Limb Muscle Contributions to ACL Loading During Single-Leg Landing
Anterior cruciate ligament (ACL) injuries commonly occurred through non-contact mechanisms during dynamic tasks such as single-leg landing (SLL). Trunk control and lower limb muscle coordination were believed to play a critical role in modulating knee joint biomechanics and ACL loading; however, their individual muscle contributions remained poorly understood due to the difficulty of in-vivo ACL force measurement. This cross-sectional study aimed to investigate the relationship between core strength, lower limb muscle forces, knee joint biomechanics, and ACL loading during single-leg landing in collegiate athletes. Three-dimensional full-body kinematics, ground reaction forces, and electromyography data were collected and integrated into a musculoskeletal modelling framework to estimate ACL loading and individual muscle force contributions. Findings from this study were expected to provide biomechanical evidence to support targeted injury-prevention and rehabilitation strategies.
Anterior cruciate ligament injuries often led to long-term consequences including early knee osteoarthritis, abnormal neuromuscular function, and reduced athletic participation. Approximately 70% of ACL injuries occurred via non-contact mechanisms, frequently during single-leg landing tasks. During such movements, ACL loading was influenced by joint kinematics, external forces, and neuromuscular coordination of both trunk and lower limb muscles. This study adopted a two-level approach. First, standard biomechanical analyses were conducted to evaluate the relationship between functional core strength and knee joint biomechanics, including knee valgus angle and knee abduction moment during SLL. Second, a musculoskeletal modelling approach was employed to quantify the contribution of individual trunk and lower limb muscles to ACL loading.
Participants performed standardized single-leg landing tasks while wearing inertial motion sensors and surface electromyography electrodes. Ground reaction forces were recorded using a force platform. A full-body musculoskeletal model was scaled to participant anthropometry and used to estimate muscle forces and ACL loading during the landing phase. Statistical analyses included linear regression and linear mixed-effects modelling to examine relationships between muscle forces, knee biomechanics, and ACL loading.
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