The aim of the study was to examine the perceptions of training data feedback from key stakeholders within the coaching process of professional soccer clubs. A survey assessed the importance of training data towards reflection and decision-making, potential barriers and player preferences. 176 participants comprising coaches, players and performance staff completed the survey. The training data coaches most commonly identified as wanting to see to support reflection was ‘high-intensity’ actions and variables recognised by the coach as ‘work rate/intensity’. All stakeholders reported training data as at least somewhat important in guiding their coaches’ practices, with lack of a common goal and high volumes of information being the main barriers to effective feedback of training data. Players deemed feedback as positive to changing their behaviour, with total distance, high-speed running and sprint distances as the information they would most like to see. It would be likely to be looked at via message or pinned up in the changing room. Training data is seen as an impactful and effective tool for use by all key stakeholders. Despite this, its use can be optimised by increasing opportunities for informal reflection, using less information, and improving communication of data.

The aim of this review was to summarise the methods used to predict and assess maturity status and timing in adolescent, male, academy soccer players. A systematic search was conducted on PubMed, Scopus, Web of Science, CINAHL, Medline and SPORTDiscus. Only experimental studies including male, academy players aged U9-U18 years registered with a professional soccer club were included. The methodological quality of the included studies was assessed using guidelines from the Framework of Potential Biases. Fifteen studies fulfilled our inclusion criteria. Studies were mainly conducted in European countries (n = 12). In total, 4,707 players were recruited across all 15 studies, with an age range of 8–18 years. Five studies were longitudinal, two studies were mixed-method designs and eight studies were cross-sectional. Due to high heterogeneity within the studies, a meta-analysis was not performed. Our findings provided no equivalent estimations of adult height, skeletal age, or age at PHV. Discrepancies were evident between actual and predicted adult height and age at PHV. The Bayley-Pinneau [1952], Tanner-Whitehouse 2 [1983] and Khamis-Roche [1994] methods produced estimates of adult height within 1cm of actual adult height. For age at PHV, both Moore [2015] equations produced the closest estimates to actual age at PHV, and the Fransen [2018] equation correlated highly with actual age at PHV (>90%), even when the period between chronological age and age at PHV was large. Medical imaging techniques (e.g., Magnetic Resonance Imaging, X-Ray, Dual energy X-ray Absorptiometry) demonstrated high intra/inter-rater reliability (ICC = 0.83–0.98) for skeletal maturity assessments. The poor concordance between invasive and non-invasive methods, is a warning to practitioners to not use these methods interchangeably for assessing maturational status and timing in academy soccer players. Further research with improved study designs is required to validate these results and improve our understanding of these methods when applied in this target population.

The relative age effect (RAE) is characterised by an overrepresentation of athletes born earlier in the selection year. Whilst an RAE is consistently evident in male soccer, examinations in female players remain limited. The aim of the present study was to examine the influence of sex, as well as age, success, and playing status in European soccer players. The sample consisted of a total of 6546 soccer players from 55 soccer nations that competed in recent European Championship qualification campaigns. Results indicated an evident RAE in male [p = 0.017] but not female [p = 0.765] players. Male players were over-represented by players born in the first quartile for the U17 [p < 0.001] and U19 [p = 0.001] levels, however, this over-representation did not transfer to senior levels. No RAE was observed at any level for female players. Inside each age group, a slight selection bias towards those born in the first quartile for successful squads was observed but did not significantly differentiate between qualification status for either male or female players. Results from this study highlight the disparity in RAE prevalence between male and female players and raise further questions regarding the value of selecting relatively older players to metrics of success, transition, and selection for senior international soccer.

The activities soccer players engage in during their formative years are thought to significantly contribute to the acquisition of expert performance. Whilst this area has seen great interest in male players, there has been little research in females. The study examined developmental activities engaged in by professional female soccer players in England. 56 female soccer players that had either progressed to professional status in adulthood (professional), or did not (ex-academy), completed the Participant History Questionnaire. Professional players started engaging in soccer at an earlier age than their ex-academy counterparts, resulting in greater engagement in practice and play during childhood. During adolescence, professional players engaged in higher amounts of practice than ex-academy players. Engagement in competition and practice was rated as high in physical and cognitive effort by all, yet ex-academy players reported higher levels of physical effort during early adolescence, and cognitive effort during late adolescence. Findings provide an illustration of the talent pathways of professional female soccer players in England and may inform future talent development systems. Large interindividual variation in soccer-specific and other-sport activity data highlight the importance of further understanding the environments of individual soccer nations and their potential impact on the talent identification and development processes.

The aims of the study were to examine the relative age effect (RAE) in youth female soccer players in the United States (US) and the influence of birth year, playing position, estimated maturation and skill ratings. The sample consisted of 3,364 youth female soccer players who were active in the...