Abstract

Anterior cruciate ligament (ACL) injuries are more prevalent in female athletes compared to male athletes. Researchers have explored the mechanism of an ACL injury in both males and females using mathematical modeling, interview, in-vivo arthroscopy, clinical evaluation, cadaver studies, motion analysis, and electromyography. However, an unexpected perturbation that mimics an ACL injury mechanism has not yet been used. Therefore, this study explored lower extremity muscle activity following an unexpected perturbation that mimics the mechanism of an ACL injury as well as the contribution of the initial stance of the athlete to an injury.
Female Concordia varsity athletes were recruited in Montreal, QC. Data was collected using the VICON motion capture system, Noraxon DTS EMG, and a goniometer. Participants were asked to maintain balance on their non-dominant leg during unexpected perturbations in the lateral, posterior, and rotational motions as well as a combination motion that mimics an ACL injury mechanism.
The mean EMG values were greatest during the post-perturbation phase for all muscles compared to the pre-perturbation and perturbation phases for both knee conditions. The time of occurrence of the maximum EMG values revealed that the muscles reached the maximum EMG value later following the onset of perturbation in the rotation direction in order to stabilize the knee joint and/or maintain balance during the lateral, posterior, and combination perturbations.