Physical development, and progression to professional soccer, of elite child and adolescent academy players

The research described within this thesis was undertaken to investigate the physical development, and progression to professional soccer, of elite child and adolescent academy players. Firstly, a detailed understanding of professional practitioners perceptions of physical performance in soccer was developed. Secondly, a valid and reliable battery of physical field tests was established to examine the physical performance characteristics of elite child and adolescent soccer players. Finally, this battery of physical performance tests was administered to elite child and adolescent players in English professional soccer academies over a three year period. Coaches (n=170), fitness professionals (n=172) and players (n=101) perceptions of physical performance in soccer were assessed by means of a questionnaire. Speed was considered the principle physical attribute by coaches, with 80.5% deeming it as very important . Most coaches (88.8%), fitness professionals (93.0%) and players (89.1%) believed the relative importance of each physical attribute differed according to playing position. A players physical attributes were regarded by coaches as important (44.1%) and very important (41.8%) in the process of offering professional playing contracts. Most coaches (71.2%), fitness professionals (68.6%) and players (65.3%) thought international players physical attributes were different to club players. Nearly all coaches (93.5%), fitness professionals (86.6%) and players (83.2%) believed the physical attributes of players had become more important in the modern day game. It was widely considered by coaches (73.5%), fitness professionals (52.9%) and players (74.3%) that players from certain ethnic groups were naturally more physically able. Logical validity of physical performance testing was demonstrated by the majority of coaches (97.0%), fitness professionals (93.5%) and players (83.1%) considering testing to be an important aspect of preparation in soccer. Construct validity of vertical jump (RJ; CMJ; CMJA), sprint (10 m and 20 m) and agility tests was shown by their ability to distinguish between different age groups (p<0.01) and ability groups (p<0.05) of players. Absolute reliability of the physical performance tests was established with repeatability on the vertical jump tests ranging from 3.2 cm to 3.5 cm for the RJ and CMJA, respectively, whilst repeatability on the sprint tests ranged from 0.07 s to 0.24 s on the 10 m sprint and agility test, respectively. ICC and PCC values to assess the relative reliability of the physical performance tests were all high (>0.90) ranging from 0.96 for the agility test to 0.99 for the 20 m sprint.