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Lower Extremity Biomechanics and Cognition: Implications for Noncontact Anterior Cruciate Ligament Injuries and Relevant, Practical Applications




Holmes, Hillary

Type of Degree

PhD Dissertation



Restriction Status


Restriction Type

Auburn University Users

Date Available



Cognition, like reaction time, visual processing, and decision-making, is associated with neuromuscular control and noncontact injuries, including noncontact anterior cruciate ligament (ACL) injuries. The persistent high rates of recurring ACL tears may result from the lack of cognition in research and application. Aim 1 investigated biomechanists’ and coaches’ knowledge, perceptions, and application of cognition relating to performance and injury. More coaches valued cognition in application with athletic performance. Biomechanists and coaches lacked knowledge on cognition and injury, providing an avenue for enhanced research in ACL biomechanics. Aim 2 integrated cognition with drop jumps to identify relationships with mechanics. Decision-making during drop jumps significantly changed relationships between increased leg stiffness and decreased ground contact time, and between increased vertical ground reaction force (vGRF) and decreased leg deformation, revealing that cognition should be considered when interpreting these common relationships. Cognition did not influence leg stiffness but did performance (jump height, reactive strength index, ground contact times), meaning neuromuscular control involving timing along the force-time curve may be related to cognition. Aim 3 investigated the influence of ACL reconstruction (ACLR) on neuromuscular control under the same cognitive drop jump protocol and with standard cognitive tests. Cognitive performance resulted in improved models predicting neuromuscular control (sagittal plane knee joint angular impulse, vGRF impulse, and knee joint power), especially in the landing phase and among tests with different visual demands. There is value in integrating cognition with drop jumps in people with an ACLR.