The relationships between performance and ACL loading during athletic tasks

Anterior cruciate ligament (ACL) injuries are common sports related knee injuries. While increasing performance and decreasing ACL injury risks are both important for athletes, the underlying relationships between performance and ACL loading are still unknown. Studying the relationships between performance and ACL loading can provide important information in understanding injury mechanism as well as developing injury prevention strategies.;In the current study, eighteen male and eighteen female collegiate aged recreational athletes conducted stop-jump and side-cutting tasks with different performance demands and techniques. Performance including jump height, approach speed, take-off speed, stance time, and mechanical work were evaluated among different jumping and cutting conditions. Peak ACL forces were estimated from an ACL loading model. ACL loading variables and peak ACL force variables were compared among different jumping and cutting conditions. The acute effects of performance demands on ACL loading were evaluated. The acute effects of movement patterns that should decrease ACL loading on performance outcomes were determined. Gender differences in lower extremity biomechanics were evaluated as a secondary purpose.;ACL loading increased when the movement speed increased. Soft landing and landing with increased knee flexion decreased ACL loading but also decreased jump height and movement speed and increased mechanical work, which indicated decreased performance. Males and females demonstrated different knee sagittal plane motion.;For individuals whose priority is injury prevention but not performance, adapting a slow movement pattern or soft landing pattern might decrease ACL injury risks. However, fast movements might not be avoidable during real sports competitions. The results suggest the importance of considering performance and ACL loading as a combined unit during injury risk evaluation and injury prevention. It is necessary to completely report the changes in performance in order to have a thorough understanding of training effects. The gender differences might provide information in developing gender specific ACL injury prevention programs. However, the current study only evaluated the acute relationships between performance and ACL loading. Long-term training effects on the relationships between performance and ACL loading need further investigations.