Investigating the dietary habits of adolescent academy soccer players

Academy soccer players partake in high volumes of training and match-play, but limited information exists regarding the optimal dietary practices to fuel such demands. Accordingly, the aims of the thesis were threefold: (1) to identify an accurate method of energy intake assessment which quantifies any self-reporting bias bespoke to Academy soccer players, (2) to provide a quantification of the energy intake and energy expenditure of Academy soccer players over a ‘typical’ training week, specifically highlighting any fluctuations in energy balance, (3) to investigate potential strategies to optimise dietary practices of Academy soccer players to reduce any identified energy deficits, whilst also examining the impact on soccer performance variables. Chapter 3 aimed to explore the agreement between researcher observed energy intake and self-reported energy intake in male Academy soccer players using a combined selfreported, weighed food diary and 24 h recall method. Considering the widely reported bias associated with using isolated self-report measures, the accuracy of a combined method was examined. Findings suggested that the combined dietary data collection method is an acceptable alternative to researcher observed approach when assessing energy intake in Academy soccer players, providing that appropriate adjustment was applied for the minor systematic under-reporting. Chapter 4 investigated the energy intake and expenditure of Academy soccer players during a competitive week. The combined method was used to measure energy intake in conjunction with accelerometry to quantify energy expenditure. Findings highlighted that the mean daily energy intake of Academy soccer players was lower than the energy expended during a competitive week, producing significant daily energy deficits. The magnitudes of these deficits were greatest on match and heavy training days. Furthermore, pre-match dietary practices were identified as a concern, reporting inadequate levels of energy intake to fuel match-play. Chapter 5 investigated the physiological and performance effects of increasing prematch energy intake prior to simulated soccer match-play, with the aim of reducing the previously identified significant negative energy balance. Findings demonstrated that Academy soccer players are able to increase pre-match energy intake without experiencing abdominal discomfort, addressing the previously identified energy deficit on such days. Furthermore, whilst increasing habitual energy intake produced limited benefits to physical performance, increased dribbling speed was identified, which may have practical application to match-play. In summary, this research has provided further information concerning the dietary practices of Academy soccer players, a population which has received limited focus, despite substantial implications considering the high demands of training and matchplay in combination with maintaining growth and maturation. Overall findings demonstrate that energy intake remains relatively stable throughout the week, failing to account for the periodised approach to training load. Players are subsequently experiencing significant daily energy deficits in particular during heavy training and match-days. Furthermore, whilst strategies to increase pre-exercise energy intake may help reduce such deficits, limited effects on physiological and soccer-specific performance were identified