Relative age and biological maturity-related selection biases in male youth soccer across different competitive levels within a national association.

OBJECTIVES AND METHODS: This study aimed to examine whether biological maturation and relative age selection biases existed and varied by level of competition (regional, national, and international) in Under-15 soccer players (n = 951) within the Swedish Football Association's male player pathway. A secondary aim was to examine the relationship between relative age and body height, body weight, predicted adult height, percentage of predicted adult height (PAH%), maturity Z-score, and biological age to chronological age offset. RESULTS: The results showed a significant bias (p < 0.001), ranging from trivial-to-small in favour of relatively older players, with the most notable increase between the regional and national levels. There were also significant moderate-to-large biases in favour of early maturing players (p < 0.001), increasing in magnitude with levels of competition. PAH% (p < 0.001) and body weight (p = 0.014) showed the strongest differences across selection levels, where the bias compared to regional level was 0.23 standard deviations (SD) for PAH% at national level and 0.41 SD at international level, while body weight appeared to be particularly related to international team selection (0.36 SD in bias). Relative age showed a moderate positive correlation with PAH% (r = 0.38), but only trivial correlations with all the other biological and physical variables examined (r=-0.05-0.11). CONCLUSIONS: The lack of association between relative age and the estimates of biological maturity timing and the additional physical characteristics suggests that relative age and biological maturity are distinct constructs. We encourage critical examination of how associations select young players for national talent programmes; current practices significantly diminish the chances of selection for those who are late maturing and relatively younger.

The selection advantages associated with advanced biological maturation vary according to playing position in national-level youth soccer.

This study investigated the extent to which biological maturation selection biases existed according to playing position in national-level youth soccer. A total of 159 players from the U13 to U16 age groups in the Football Association of Ireland's national talent pathway and international representative squads had their relative biological maturity status assessed using the Khamis-Roche method for the percentage of predicted adult height at the time of observation. Players were categorised as goalkeeper (GK), central defender (CD), full-back (FB), centre defensive midfielder (CDM), centre midfielder (CM), centre attacking midfielder (CAM), wide midfielder (WM) or centre forward (CF). A series of one-sampled means t-tests were used to examine the degree to which biological maturation selection biases existed across playing positions. A non-parametric Kruskal-Wallis test was used to evaluate inter-positional differences. A small to very large selection bias in favour of early maturing players existed for GK (D = 0.7), CD (D = 1.65), FB (D = 0.49), CM (D = 0.62), WM (D = 0.78), and CF (D = 0.76) (p < 0.05). Maturational selection biases did not exist for CDM or CAM. Moreover, CD were significantly more advanced in maturation compared to FB, CDM and CAM (p < 0.05). This study supports the contention that maturation selection biases exist in youth soccer, but the magnitude of this bias is highly dependent upon playing position. The very strong maturity selection biases at the national level evidenced in this investigation highlight the need for Football Associations to explore strategies, such as futures programmes, to help to retain talented, yet late maturing athletes.

Push and Pull Factors: Contextualising Biological Maturation and Relative Age in Talent Development Systems.

In this conceptual paper, we contextualise ongoing attempts to manage challenge dynamics in talent systems in sport. Firstly, we review the broad literature base related to biological maturation, relative age, and the proposed interventions to mitigate effects. We suggest that the relative age effect may be a population level effect, indicative of deeper phenomena, rather than having a direct effect on challenge levels. In contrast, we suggest that biological maturation has a direct effect on challenge at the individual level. Therefore, our main critique of many existing approaches to the management of challenge is a lack of individual nuance and flexibility. We suggest the necessity for talent systems to adopt a more holistic approach, conceptualising biological maturation and relative age within a broader field of "push and pull factors" that impact challenge dynamics in talent development in sport. Finally, we provide practical guidance for talent systems in their approach to relative age and biological maturation, recognising that there is no "gold standard". Instead, there is a need to recognize the highly individual and contextual nature of these concepts, focusing on strategic coherence through talent systems for the management of selection and development processes.

International selection and competition in youth sport: pin the tail on the donkey or targeted intervention?

Across sporting contexts, there is growing debate surrounding the utility of junior international age group selection in sport. In this regard, there has been considerable focus on the age of selection, with the low conversion of athletes from junior to senior international level often used to critique the efficiency of such programmes. In this perspective article, we argue that there is a need for a more nuanced consideration of the effectiveness of international age groups in talent systems. We begin this perspective article with a synthesis of the literature pertaining to junior to senior transitions in sport, followed by the implications and opportunity cost presented by international age groups. We argue for a more contextual evaluation of international age groups relative to the performance aims of a talent system, the need for manipulation of challenge dynamics, and the resource costs of doing so (e.g., providing developmental challenges for those who have early advantage, or spreading resource amongst greater numbers for broader impact). We suggest that talent systems evaluate the opportunity cost presented by international age groups, with decisions based upon individual strategic context.

The Irish Football Player Pathway: Examining Stakeholder Coherence Throughout and Across the Player Development System.

Maximizing the efficiency of the player development system is a strategic priority for any professional football club or association. However, the successful development of a young footballer is largely dependent upon the roles and relationships of the different stakeholders invested in the developmental process. This study examined the level of horizontal (i.e., extent to which stakeholders across a pathway stage work with players in an agreed fashion to optimize their experience) and vertical (i.e., extent to which multiple stages of the pathway are coordinated and build chronologically from previous involvement toward long-term needs) stakeholder coherence throughout the Irish football player pathway following a restructuring of development policies and the implementation of a nationwide academy system between 2016 and 2020 under the Football Association of Ireland's (FAI) Player Development Plan. As a second aim, we explored each of the key stakeholders' alignment to academic talent development principles in order to provide practical recommendations for future player and coach development policies. Accordingly, a series of interviews were conducted with 31 key stakeholders currently engaged in the player pathway. These key stakeholders consisted of parents, coaches and members of the FAI as the National Governing Body for football in Ireland. Data were analyzed using Reflexive Thematic Analysis, with findings highlighting a lack of stakeholder coherence across the pathway, both vertically and horizontally. Stakeholders displayed inconsistency in their understanding of the purpose of the player pathway and its long-term strategic aims, as well as demonstrating poor and incohesive relationships with each of the different stakeholders. Moreover, talent development principles between the different stakeholders appeared well-understood overall, although the practical implementation of several of these principles in applied practice did not appear to exist. Results highlight the need for organizational intervention and structural change across the Irish player pathway to maximize long-term player development in the future. Practical implications for the FAI are discussed and recommendations are made to support optimal player development policies moving forward.

Premature Professionalisation or Early Engagement? Examining Practise in Football Player Pathways.

There is a growing debate, both in the academic and sporting worlds, about the most appropriate pathway for high potential young players in sport. In this regard, there has been a considerable focus on the age of selection into structured talent development pathways and the nature of the experience once players have been recruited. Given the economic and reputational currency associated with developing professional footballers in particular, it is unsurprising that professional football clubs continue to invest significant financial resources into their academy structures. Understandably, this recruitment policy has attracted substantial attention within the media and research community, with ethical concerns arising surrounding the impact early selection may have on the welfare and the experiences of the young players within the pathway. The aim of this perspective article was to critically consider the research underpinning the early engagement practises of football clubs and the extent to which, and how, the pathway can provide players with the most appropriate starting point for their development. This evidence points to the need to look beyond the prevalent 'early specialisation vs. diversification' debate in youth sport towards a consideration of an early engagement perspective that reflects the biopsychosocial influences on talent development and the socio-political environment that influences decisions. We provide practical recommendations focused on the quality of the early engagement experience.

Optimization of Ultrasound-Mediated Drug Delivery for Treatment of Onychomycosis.

BACKGROUND: Onychomycosis is a fungal nail disorder that does not have a successful cure due to the poor permeability of topical anti-fungal drugs through the nail. This study utilizes ultrasound to increase the permeability of the nail to the topical drugs currently used in clinic. The first aim of this study was to optimize ultrasonic parameters within the temperature increase limits set by the American Institute of Ultrasound in Medicine (AIUM) and the British Medical Ultrasound Society (BMUS). The second aim of the study was to evaluate the optimized parameters for a cause of action of either cavitation (the creation of micrometer pores in the nail barrier) or acoustic streaming (a steady fluid motion which may help push the drug through the nail). METHODS: Porcine and human nails are used in the five studies. PZFlex Modeling Software is used to model the temperature increase in the toe as a result of ultrasonic application and these results were used to develop the three parameters tested throughout the rest of the studies. The three parameters tested were 1 min of continuous ultrasonic application, 3 min of 50% ultrasonic application and 5 min of 50% ultrasonic application. In order to address the second aim of our research work, these three parameters were tested for the presence of streaming and cavitation. RESULTS: At the three tested parameters, the most permeation of the nail occurs with 1 min of continuous application of ultrasound to the nail. It was also found that there was limited cavitation and significant streaming at all three parameters. This suggests that streaming may be the main mechanism-of-action in ultrasound-mediated drug delivery through the nail. CONCLUSION: The parameter of 1 min of continuous ultrasonic testing will continue to be employed as the testing is moved to a rabbit model of onychomycosis.