Exploring the associations of lower limb strength, injury and performance in academy football

For those competing in academy football, absence from training and match play due to injury can hinder the development of important football skills (i.e., tactical technical, physical and psychological) that are required to be successful at senior level. Evidence from senior cohorts has suggested that significant relationships exist between strength, injury and performance, yet information relating to academy footballers remains sparse. Therefore, an improved understanding of the associations of lower limb strength, injury, and performance specific to academy footballers, could help improve injury reduction, athletic enhancement and ultimately aid player development. The aim of study 1 (chapter 2) of this thesis was to systematically review studies investigating injury prevalence, incidence and severity in high-level male youth football. Electronic databases Academic Search Complete, CINAHL, Cochrane, Medline, PubMed, SPORTDiscus and Web of Science were systematically searched to identify eligible studies. The novel findings from this study were that youth footballers had a high probability of sustaining a time loss injury over a typical youth season and that a large portion of training and competition time was lost to injury. In chapter 4, study 2 explored novel field-based strength assessments and their relationships with both sprint and change of direction (COD) performance in male academy footballers. The unique findings from this study were that all scaled strength assessments were associated collectively with 'running ability' and independently with linear sprint and COD ability. Study 3 aimed to investigate the impact of non-contact lower limb injury on scaled hip, groin and knee flexor strength development in male academy youth footballers. The novel observations of study 3 were that injury only had a trivial impact on strength development and stronger footballers at pre-season experienced strength loses while those weaker players gained strength across the season. The final study (4) investigated the association of preseason lower limb scaled strength measures and subsequent non-contact lower limb injury in male academy footballers. The unique finding from study 4 was that stronger preseason scaled isometric hip adduction strength was associated with future non-contact injury. Overall the data from these studies characterised injury pertaining male to academy footballers and provided novel evidence for the efficacy of use for multiple strength devices to monitor and screen academy footballers to help guide tailored interventions.