Effect of footwear and overhead goal on the Landing Error Scoring System

A large proportion of the population undertakes sport and exercise either for recreation or competition. However, with increased participation in sport and exercise, the occurrence of sport-related injuries also increases. Anterior Cruciate Ligament (ACL) injuries are injuries to the knee and one of the most common injuries in a sporting environment that occur from noncontact mechanisms. The Landing Error Scoring System (LESS) is a common screening tool used to identify individuals who are more at risk of sustaining an ACL injury based on double-leg jump-landing (DLJL) kinematics. Despite the LESS demonstrating good-toexcellent reliability and predictive value, the LESS is sensitive to various factors (e.g., protocol alterations) and has been criticised for lacking sport specificity. Despite studies conducting the LESS both with and without footwear and using an overhead goal during jumping tasks to increase sport specificity, to date, there is no research comparing LESS outcomes based on the presence/absence of footwear or presence/absence of an overhead goal. Chapter One summarises literature surrounding sports injuries, ACL injuries, injury aetiology, injury prevention models, and injury risk screening tools used in sports with a focus on the LESS. Footwear and cueing in sports are also addressed. Chapter Two is experimental and compares overall LESS scores, group- and individual-level injury risk categorisation, specific LESS errors, and jump heights between footwear and no footwear conditions. Chapter Three is experimental and compares these same outcome measures between overhead goal and no goal conditions. Chapter Four summarises the key findings from the two experimental chapters, and addresses the limitations, strengths, and future research directions arising from this Thesis. In Chapter Two, 80 participants (55% male) performed a DLJL task where they landed from a 30-cm high box to 50% of their own body height and immediately jumped vertically for maximum height for LESS assessment. Participants completed three trials under two randomordered conditions: with and without footwear. Group mean LESS scores were greater (0.3 errors, p = 0.022) and jump heights were lower (0.6 cm, p = 0.029) in the footwear than barefoot condition, but differences were trivial and not clinically meaningful. Although the number of high-risk participants was comparable between groups (p = 1.000), categorisation was inconsistent for 16.25% of individuals and the occurrence of four of the 17 specific landing errors significantly differed between conditions. Based on the study findings, footwear does not appear to meaningfully influence mean LESS scores, risk categorisation, or jump height at a group level. At an individual level, footwear can affect risk categorisation and landing strategies. Hence, use of a consistent protocol is recommended in clinical setting, and use of footwear is advised for assessing injury risk given the predictive value of the LESS barefoot is unknown. In Chapter Three, 76 participants (51% male) performed a DLJL task where they landed from a 30-cm high box to 50% of their own body height and immediately jumped vertically for maximum height for LESS assessment. Participants completed three trials under two randomordered conditions: with and without an overhead goal. Mean LESS scores were greater (0.3 errors, p < 0.001) with the overhead goal, but this small difference was not clinically meaningful. Similarly, although the number of high-risk participants was significantly greater with the overhead goal (p = 0.039), the 9.2% difference was trivial. Participants jumped 2.7 cm higher with the overhead goal (p < 0.001) without affecting the occurrence of any specific LESS errors. Based on the results found, performing the LESS with an overhead goal enhances sport specificity and elicits greater vertical jump performances with minimal change in landing errors and risk categorisation. Adding an overhead goal to LESS might enhance its suitability for injury risk screening, although the predictive value of LESS with an overhead goal needs confirmation