ACL Injury Prevention Training Results in Modification of Hip and Knee Mechanics During a Drop-Landing Task

Background: Injury prevention training has been shown to be effective in reducing the incidence of noncontact anterior cruciate ligament (ACL) injury; however, the underlying reason for the success of these training programs is unclear. Purpose: To investigate whether an ACL injury prevention program that has been shown to reduce the incidence of ACL injury alters sagittal plane hip and knee biomechanics during a drop-landing task. Study Design: Descriptive laboratory study. Methods: Thirty female club soccer players (age range, 11-17 years) with no history of knee injury participated in this study. Kinematics and ground-reaction forces were collected while each participant performed a drop-landing task prior to and immediately after participation in a 12-week ACL injury prevention training program. Results: After ACL injury prevention training, participants demonstrated decreased knee extensor moments (P = .03), increased energy absorption at the hip (P = .04), decreased knee-to-hip extensor moment ratios (P = .05), and decreased knee-to-hip energy absorption ratios (P = .03). Conclusion: Participation in an ACL injury prevention training program decreased reliance on the knee extensor muscles and improved use of the hip extensor muscles, which may explain the protective effect of this type of training program on ACL injury. Clinical Relevance: Based on these findings, clinicians can better understand how ACL injury prevention training, such as the Prevent Injury and Enhance Performance (PEP) Program, may change movement behavior at both the hip and knee. Furthermore, the study findings may support the implementation of the PEP Program, or a similar program, for clinicians aiming to improve use of the hip in an effort to reduce knee loading and consequent injuries.