Degree Type


Date of Award


Degree Name

Doctor of Philosophy





First Advisor

Jason C. Gillette


Despite our best efforts, anterior cruciate ligament injury rates remain high in many athletic populations. Over the past two decades, investigations have sought to identify the potential role cognition may play in the functional injury mechanism. Across the body of literature, there is a general consensus that rapid, reactive environments found in team sports increase injury risk. But the precise biomechanical change in lower extremity control has been inconsistently identified across multiple investigations. We previously identified that an important, often uncontrolled component of rapid reactive movements is the timing of the directional cue to which the athlete responds. Reductions in time that the athletes have available to react to this directional cue undermines lower extremity control and may increase injury risk. In sport, this may be caused by a deceptive opponent masking their movement direction. We sought to further explore components of perception and action that may alter this available time to react. Across three investigations, we explored the potential effects of performance demands, erroneous movement direction predisposition, and more information-rich, probabilistic directional cues and their impacts on ACL injury risk factors. We identified that contexts that may delay the identification of the correct directional cue are likely to result in a reduction of lower extremity control, which may alter injury risk and decrease performance. We suggest that factors that may alter perception and action time, such as neurocognitive ability and sports expertise, be trained to reduce the risk of injury in reactive environments.

Copyright Owner

Mitchell Lewis Stephenson



File Format


File Size

121 pages

Included in

Biomechanics Commons