Selection biases within an English football academy: implications of the Elite Player Performance Plan

A thesis submitted in partial fulfilment of the requirements of the University of Wolverhampton for the degree of Doctor of Philosophy.The Elite Player Performance Plan (EPPP) was introduced in 2011 in order to enhance the youth football academy system in England. Previous literature demonstrates that relative age and biological maturation are responsible for selection biases within youth football, where both factors exert an influence on anthropometry and physical performances. However, there is limited research that has examined the aforementioned factors over a prolonged period of time, and especially within academies operating under the EPPP. Therefore, the general aim of this thesis was to investigate relative age, biological maturity, anthropometric and physical performance characteristics of male youth players from an English football club, as they progressed through the developmental pathway, under the EPPP framework. The findings from Chapter 3 revealed that selection within the investigated club was heavily overrepresented by relatively older and earlier maturing players, and this persisted since the EPPP was introduced. Subsequently, Chapter 4 identified that biological maturity, anthropometry and physical performances distinguished players that were retained across the developmental pathway, in an age group dependent manner. Chapter 5 provided estimates for when the development of anthropometric and physical performance characteristics initiate, peak and plateau, according to somatic maturity. Finally, Chapter 6 demonstrated that a bio-banding intervention may influence the decision-making process adopted by academy coaches’ regarding player selection and retention. In summary, the investigations conducted within this thesis provide novel and contemporary knowledge that can be used to enhance practice within the current club. Specifically, the findings from this thesis highlight that relative age, biological maturity, anthropometry and physical performances influence player selection and retention within this academy, suggesting that policies (e.g. the EPPP) require careful evaluation so that inappropriate selection biases can be nullified. Further studies are required to corroborate and extend these findings on a wider scale through robust methodological approaches

Relative Age, Maturation, Anthropometry and Physical Performance Characteristics of Players Within an Elite Youth Football Academy

A professional English football club with Category 1 academy status was investigated to determine the magnitude of relative age effects (RAE) within the club and explore between quartile differences for somatic maturity, anthropometry and physical performances. Birth dates of 426 players from Under 9 to First Team were categorised into four birth quartiles (Q) and examined for RAEs. Additionally, data on 382 players (Under 11 to First Team) were obtained for somatic maturity, anthropometry, countermovement jump, sprint (10 and 30 m), agility T-Test, and Yo-Yo Intermittent Recovery Level 1 or 2 performance to determine between-quartile differences. Odds ratios revealed Q1 players were 6.0 times more likely to be represented than Q4 players. Multilevel modelling demonstrated similarities between-quartile for each variable across all age groups, though there was a tendency for Q4 players to outperform Q1 players between Under 11 and Under 18 groups. Strong RAEs exist within this club as well as a tendency to select players demonstrating advanced growth and/or maturity, with some indication that higher categorised academies in England may be at risk of amplified selection biases. Talent identification strategies in elite youth football should actively seek to adopt novel approaches to reduce selection biases and avoid wasted potential

Vector navigation in walking bumblebees

Path integration is a computational strategy that allows an animal to maintain an internal estimate of its position relative to a point of origin. Many species use path integration to navigate back to specific locations, typically their homes, after lengthy and convoluted excursions. Hymenopteran insects are impressive path integrators, directly returning to their hives after hundreds of meters of outward travel. Recent neurobiological insights have established hypotheses for how path integration vectors could be encoded in the brains of bees, but clear ways to test these hypotheses in the laboratory are currently unavailable. Here, we report that the bumblebee, Bombus terrestris, uses path integration while walking over short distances in an indoor arena. They estimate accurate vector distances after displacement and orient by artificial celestial cues. Walking bumblebees also exhibited systematic search patterns when home vectors failed to lead them accurately back to the nest, closely resembling searches performed by other species under natural conditions. We thus provide a robust experimental system to test navigation behavior in the laboratory that reflects most aspects of natural path integration. Importantly, we established this assay in an animal that is both readily available and resilient to invasive manipulations, as we demonstrate with the retention of the homing behavior post-anesthesia and surgery. In the future, our behavioral assay can therefore be combined with current electrophysiological techniques, opening a path toward directly probing the neural basis of the sophisticated vector navigation abilities of bees

The Influence of birth quartile, maturation, anthropometry and physical performances on player retention: Observations from an elite football academy

This is an accepted manuscript of an article published by Sage in Journal of Sports Science and Coaching on 25/02/2020, available online: https://journals.sagepub.com/doi/10.1177/1747954120906507 The accepted version of the publication may differ from the final published version.Understanding the factors that influence player retention within elite youth football can be used to enhance current practices. This study investigated an English Category 1 academy to determine if birth quartile, somatic maturity, anthropometric and physical performance characteristics are associated with player retention across the developmental pathway. Birth dates of 355 elite players from U11 to U21 groups were categorised into birth quartiles and logistic regression (odds ratio) analysis was used to determine differences in retention. Multilevel modelling compared somatic maturity, anthropometry, countermovement jump, sprint time (10 and 30 m), agility T-test, Yo-Yo Intermittent Recovery Level 1 or 2 performance between retained and dropout players. Logistic regression (odds ratio) analysis revealed no significant differences between birth quartiles for the likelihood of being retained across age groups. Multilevel modelling revealed that retained players were typically older, advanced in maturity, and superior in body size and physical performances compared to dropouts, with small to medium effect sizes typically observed. This study indicates that within a highly selective cohort of young football players, somatic maturity, anthropometric and physical performance characteristics, but not birth quartile, distinguish individuals that are subsequently retained or dropout in an age group dependent manner. Youth football organisations should seek to implement multidisciplinary and dynamic talent selection and retention strategies in order to prevent the inappropriate discrimination and loss of talented young players