Although retained players covered more low-speed distance than released players, further study of the actions comprising low-speed distance during match-play is warranted to better understand factors differentiating retained and released players.

The present study examined if elite youth male association football (soccer) players aged 8-19 y (n = 2,875) from the English talent development system, who ultimately achieved professional status differed in stature, body mass, and physical performance (20-m sprint speed, slalom agility speed, vertical counter-movement jump with arm swing jump height, multistage fitness test distance) compared with their non-professional peers. The study also examined the longitudinal pattern of development of stature, body mass, and physical performance, and if this was different between future professionals and non-professionals, while considering the effects of playing position. Multilevel modeling of the 8,898 individual (player-occasion) data points suggested that from age 12.0, the future professionals performed better in a vertical counter-movement jump with arm swing test and slalom agility test than future non-professionals, and improved at a faster rate, so that by age 18.0 the differences in vertical counter-movement jump with arm swing and slalom agility performance were 1.7 cm (p < 0.001, d = 0.3) and 0.14 s (p < 0.001, d = 0.5), respectively. In addition, future professionals were faster (by 0.02-0.04 s on the 20-m sprint, p < 0.001, d = 0.2) and ran further in the multistage fitness test (by 47 m, p = 0.014, d = 0.2) than future non-professionals throughout their development, but there were no differences in stature or body mass during development between the groups. Whereas, multistage fitness test performance improved linearly with age, the development of all other physical characteristics was non-linear. There were inter-individual differences in the development of all characteristics, and there were differences between playing positions in the development of all characteristics. Thus, in summary, future professionals jump higher, are more agile, faster, and more endurance fit than future non-professionals as they age, and the pattern of development is different in professionals and non-professionals for vertical jumping and slalom agility performance.

The aims of the current study were: 1) to examine age-related differences in match-running performance with two different approaches (speed vs metabolic power) in U13 to U18 Japanese elite soccer players; 2) to examine age-related differences in technical match performance in U13 to U18 Japanese elite soccer players. Participants were 110 field players from academies of two professional soccer clubs in Japan. Forty-eight 11-aside official league matches (13, 6, 9, 7, 6 and 7 matches for U13, U14, U15, U16, U17 and U18 age groups, respectively) were analyzed (152 complete match-files). Global Positioning System (15Hz) and video analysis were employed to analyze running and technical performance during matches, respectively. Total distance covered in absolute terms (U13 < (U14 and U15) < (U16-U18), P < 0.05 for all), high-intensity running distance ((U13-U15) < (U16-U18), P < 0.05 for all) and distance covered during the metabolic power zone ≥ 35 w•kg-1 relative to match playing time ((U13 < U16), (U13-U15) < (U17 and U18), P < 0.05 for all), increased with age. The speed zone based approach (high-intensity running distance, ≥ 4.0 m•s-1) underestimated high-intensity demands compared to the metabolic power zone based approach (≥ 20 W•kg-1) by ~33% to ~57% (P < 0.01 for all), with the underestimation declining with age (P < 0.001). Pass accuracy improved with age from 73% at U13 to 85% at U18 (P < 0.001). Therefore, distance covered at high speeds and at high metabolic powers, and pass accuracy increase with age. Moreover, the speed zone based approach underestimates the demands of match play in Japanese elite youth soccer players. The current results could support coaches to develop players, identify talent and produce age-specific training programs.

The purpose of this study was to investigate the effects of playing position, pitch location, team ability and opposition ability on technical performance variables (pass, cross, corner, free kick accuracy) of English Premier League Soccer players in difference score line states. A validated automatic tracking system (Venatrack) was used to code player actions in real time for passing accuracy, cross accuracy, corner accuracy and free kick accuracy. In total 376 of the 380 games played during the 2011–12 English premier League season were recorded, resulting in activity profiles of 570 players and over 35’000 rows of data. These data were analysed using multi-level modelling. Multi-level regression revealed a “u” shaped association between passing accuracy and goal difference (GD) with greater accuracy occurring at extremes of GD e.g., when the score was either positive or negative. The same pattern was seen for corner accuracy away from home e.g., corner accuracy was lowest when the score was close with the lowest accuracy at extremes of GD. Although free kicks were not associated with GD, team ability, playing position and pitch location were found to predict accuracy. No temporal variables were found to predict cross accuracy. A number of score line effects were present across the temporal factors which should be considered by coaches and managers when preparing and selecting teams in order to maximise performance. The current study highlighted the need for more sensitive score line definitions in which to consider score line effects.

This mixed-longitudinal study examined the development of match skills in elite male youth footballers (aged 11-18 years), while considering the effect of playing status, maturity status, and playing position. Across two seasons, 126 elite male youth footballers were assessed in 1-10 competitive matches (401 player-matches). For each match, the on-the-ball actions of each player were recorded using a notation system. The match skills observed were frequencies of successful passes, on-target shots, dribbles, crosses, clearances, and tackles/blocks/interceptions. Multilevel Poisson analysis was used to model the development of players, with regard to each match skill. Modelling revealed significant (p < .05) age-related changes in the frequency of several match skills. That is, dribbles increased, on-target shots, crosses and tackles/blocks/interceptions decreased, whereas changes in successful passes were position-specific. Players retained by an academy performed more dribbles compared to released players (p < .05) (e.g. retained vs. released 18-year-old centre forward = 4.1 vs. 2.0 dribbles per hour), and retained defenders performed more tackles/blocks/interceptions than released defenders (p < .05) (e.g. retained vs. released 18-year-old, on-time maturing centre back = 12.5 vs. 10.2 tackles/blocks/interceptions per hour). Moreover, compared to on-time maturing players, early maturing players performed more tackles/blocks/interceptions (p < .05) (e.g. on-time vs. early maturing retained 18-year-old centre back = 12.5 vs. 15.2 tackles/blocks/interceptions per hour). Playing position affected all match skills (p < .05). The developmental profiles of match skills presented here may support experts in identifying and developing talented footballers across a wide age range, while considering the influence of maturity status and playing position.