Relative Age Effect Research Articles

Gender Differences for the Relative Age Effect on Physical Skills and Emotional Intelligence in Child Volleyball and Soccer Athletes.

Background/Objectives. The goal of this study was to assess the relative age effect and its relationship with the development of physical abilities and emotional intelligence in Colombian child athletes according to gender and the sport practiced. Methods. A cross-sectional correlational design was used. A total of 135 Colombian soccer and volleyball athletes, 62 boys and 73 girls, voluntarily participated with an average age of 13.25 ± 0.59 years. Physical skills such as SJ, CMJ, CMJA, 5, 10, and 15 m speed, CODS agility, and emotional intelligence were evaluated. Results. Statistically significant differences were found in the mood variables between Q1 and Q4 (p = 0.047, ηp2 = 0.08) and Q2 and Q4 (p = 0.035, ηp2 = 0.08). These differences are also present in the interpersonal variable between Q1 and Q4 (p = 0.003, ηp2 = 0.12), Q2 and Q4 (p = 0.009, ηp2 = 0.12), and, finally, in the total emotional quotient between Q1 and Q4 (p = 0.013, ηp2 = 0.13), Q2 and Q3 (p = 0.024, ηp2 = 0.13), and Q2 and Q4 (p = 0.005, ηp2 = 0.13). Conclusions. Based on the findings of this research, it can be concluded that the relative age effect appears to be sensitive to CODS agility, 15 m speed, and SJ power variables concerning gender and sport. Jump height for CMJ concerning gender and CMJA jump concerning sport were considered. Emotional intelligence appears to be a variable sensitive to the relative age effect.

Looking beyond relative age to understand relative advantage and disadvantage in talent development.

In this perspective article, we argue for a broader consideration of relative advantages and disadvantages in youth sport; a lens that considers the complex biopsychosocial factors that influence athlete development beyond relative age. We begin with a brief overview of Relative Age Effects (RAEs), with a particular focus on the proposed underlying mechanisms, followed by a discussion of the cultural and organisational considerations and implications that talent systems must consider when implementing interventions to counteract RAEs. We conclude by proposing key directions for future research in respect to RAEs and talent development more broadly. We argue that there is a need to consider the highly complex nature of RAEs, but also that there are no clear solutions to the issue of RAEs in youth sports, and that proposed solutions may come with unintended consequences. This should encourage us to experiment more, not less, with diverse ways of providing meaningful sports experiences that promote learning, psychosocial development, and performance. We suggest an urgent need for greater practical and research focus on supporting coaches, as they have the greatest capacity to understand the needs of individual athletes. In addition, systemically working towards equal access to skilful coaches. We encourage a shift in focus beyond descriptive methodologies of RAEs toward transformative research methodologies that include action-based research, complex interventions that incorporate context-sensitive qualitative methods, and other participatory research approaches.

The interaction of relative age with maturation and body size in female handball talent selection.

The relative age effects (RAEs) and biological maturation are two distinct factors that have been identified to affect talent identification and selection. Previous research has suggested that talent selection should include sport-specific technical tasks instead of body size and/or physical test measurements, assuming that the technical tasks are less influenced by variations in maturation. Our purpose was to examine the prevalence of RAEs and to assess biological maturity, body size, and body composition within a single talent selection program for female handball players. Team coaches' recommendations, handball-specific drills, and in-game performance were the selection criteria. Birth distribution of all U14 female handball players were analysed (N = 3198) grouped in two-year age cohort. Measurements of body size, body composition (InBody 720), and bone age were performed in all players who were selected to participate in the selection program (n = 264) (mean±sd age: 13.1±0.6 years) and in a sample of not-selected players (n = 266) (mean±sd age: 13.2±0.6 years). Players were grouped in quarter-year intervals based on their date of birth. Chi-square was used to examine quartile distributions, differences between quartiles were tested with one-way analysis of variance, whereas differences between the selected and not-selected groups were examined with independent sample t-test (Cohen d effect size). Binary logistic regression was used to determine the effects of the predictors on the selection. In terms of all registered players, there was no difference in birth distribution. RAEs appeared at the first selection stage and were evident at all following stages. Quartiles differed only between the first and the last quartiles in body size and muscle mass. Only bone age differed between consecutive quartile or semi-year groups. Body size, body composition, and maturity had a significant, but of moderate power, effect on the selection. Larger body height increased the likelihood of selection by about 12%, larger muscle mass by 12% to 25%, larger bone age by 350-400%, while larger percent body fat decreased selection chances by 7%. The sport-specific criteria could not eliminate the prevalence of the RAEs. Relative age was connected to bone age, but not convincingly to body size and muscle mass. Although bone age had the largest effect on the selection, this was not associated with larger body size or muscle mass. Early maturation increased selection chances mainly during the coaches' subjective evaluation, but not convincingly when sport-specific tasks were applied. Given that differences were mostly evident between players of more than 1.5-year variation in their chronological age, one-year age cohorts within talent selection or the rotation of the cut-off dates of the bi-annual age grouping could be a promising strategy while also including maturation status and relative age in performance evaluations.

Gender and socioeconomic dimensions of relative age effects on ADHD prescriptions: Evidence from Denmark

This paper examines the impact of relative age on Attention Deficit Hyperactivity Disorder (ADHD) prescriptions among school-aged children. Using a regression discontinuity design, we leverage the quasi-experimental variation in school starting age. We use administrative data for all children aged 6–16 from 2010 to 2019 in Denmark. We find a significant decrease in ADHD prescription rates for girls who are relatively old compared to their class mates. We do not find any significant results for boys. We further test the social gradient in relative age on ADHD prescriptions and find that the effect is entirely driven by girls from low income families.

Relative Age Effect and ACTN3 R577X and ACE I/D Polymorphisms in Brazilian Football Players: An Association Genetic Study

ABSTRACT The Relative Age Effect (RAE) suggests older athletes within an annual cohort have advantages over their younger peers. We hypothesized that younger athletes could overcome these disadvantages through favorable α-actinin-3 (ACTN3) and angiotensin converting enzyme (ACE) polymorphisms. This study aimed to: 1) examine RAE prevalence among Brazilian football players; 2) investigate the distribution of the ACTN3 and ACE polymorphisms; and 3) explore the association between polymorphisms and RAE across competitive levels and positions. The sample included 627 male players from first-division Brazilian teams in four age categories: U15 (n = 172), U17 (n = 166), U20 (n = 161), and Professionals (n = 128). A control group was established using data from the general Brazilian population documented in previous studies Results showed RAE presence across all competitive levels and positions. Players with the ACTN3 R allele, especially the RR genotype, had the strongest associations with football players, particularly among defenders. On the other hand, the distribution of ACE polymorphism was not significantly different between controls and players, except in the U17 category, where the I/I genotype was more common. Relatively older players had higher total genotype scores than younger counterparts in the overall sample and defender subgroups. In conclusion, RAE is prevalent among Brazilian football players, with older athletes benefiting from favorable ACTN3 and ACE polymorphisms, contrary to our initial hypothesis.

An investigation on main effects and interactions of relative age effects and playing position in female elite football in Germany.

Athlete age-grouping and age-banding has been shown to impact sport participation and athlete development. The current study examined the impact of within-year (WYEs) and between-year effects (BYEs), and their interactions with playing position, on female participation in elite German football. The sample of 1,378 German first-league players revealed expected participation inequities within-year with relatively older players being over-represented and younger players being under-represented. From a between-year perspective there were no participation differences. The interaction of WYEs and BYEs revealed an over-representation of odd-year players in Q1, and Q2 in even years. With respect to the interaction between year effects and playing position, for WYEs the expected effect was present for goalkeepers and defenders, while there was no significant interaction for BYEs. Overall, the results offer insight regarding the impact of system structure on participation, and highlight unique characteristics associated with playing positions.

Relative age effect in male and female elite international amateur boxing

ABSTRACT This study aimed to determine whether the Relative Age Effect (RAE) was present in different sexes and age categories in 12 elite-level international amateur boxing competitions. A total of 4813 athletes competing between 2013 and 2022 were analysed. Athletes were split into four quartiles according to their birth date and compared to the expected (equal) birth date distribution using chi-squared goodness of fit. The results revealed greater RAE prevalence in youth compared to the senior group. RAE was more prominent in males compared to females, with the female group showing an inverse RAE trend. Odds ratio (OR) showed an overrepresentation of male boxers born in Q1 compared to Q4 (OR > 1.19-1.33), while senior female boxers presented an inverse trend (OR < 0.95). Odds Ratios for medallists within the youth group were greater than 1.07 (except Q3 × Q4 = 0.93) highlighting an overrepresentation of boxers born earlier in the year. A shift in strategy to reduce the RAE in young boxers whereby coaches focus less on the short-term pursuit of sporting success is encouraged. Organisations and coaches should increase awareness and provide systematic education around RAE, whilst creating equal competitive opportunities for all young boxers to reduce the extent of RAE in boxing.

The Relative Age Effect across an International Soccer Programme in Male and Female Players Aged 12 Years Old to Seniors.

The purpose of the study was to examine the prevalence of the Relative Age Effect (RAE) across an international soccer programme in male and female players aged 12 years old to seniors. One hundred forty-five male (age: 18.8 ± 4.6 years; body mass: 68.1 ± 10.2 kg; body height: 177.3 ± 10.5 cm) and 218 female (age: 15.9 ± 4.6 years; body mass: 66.2 ± 10.5 kg; body height: 170.6 ± 8.3 cm) players from a National Association were assessed. All participants were divided into four quartiles: January to March (BQ1), April to June (BQ2), July to September (BQ3), and October to December (BQ4). The results showed that the distributions for all male squads were significantly skewed, with more players than expected from BQ1 in the U-21, U-19, and U-17 and less players than expected from BQ4 in the U-19 squad. The distributions for all female squads showed significantly more players than expected from BQ1 in the U-16 and less players than expected from BQ4 in the U-14 squad. The distributions across the different positions for the male squads combined were significantly skewed with more forward players than expected from BQ1 and less forward and midfielder players than expected from BQ4. For the female squads, there were significantly more BQ1 defenders from the U-16 squad than expected. In conclusion, this study unveils significant disparities in quartile distributions among male and female squads. Moreover, the data emphasize the potential impact of heightened physical demands in certain positions on the RAE.

Relative age effect in Mexican professional and youth soccer

In youth football, categories are defined by the players’ year of birth. In one category, there can be an age difference of almost 12 months, which may manifest itself in considerable physical differences. The impact of this "relative age" is reflected in elite teams by an overrepresentation of players born in the first months of the year, called "Relative Age Effect" (RAE). In the present study, this bias was analyzed among the 4499 Mexican players (3531 men, 968 women), registered by the 18 professional clubs for the 2022 season in men’s First Division, their U20, U18, U17, U16, U14 categories, women's First Division, and their U17 categories. From every player were collected: birthday, playing position, minutes played for their teams, and their teams’ final rank in the National Championships. In all categories, except women's First Division, a statistically significant RAE was found, whose size was greater in the lower categories than in the major ones. The playing positions that presented a higher size of RAE were not the same in the different categories. A positive correlation was found between RAE and individual and team performances. These results indicate the need to take a deeper look at the selection and development processes of talented players in Mexico, because players initially favored by their greater relative age do not reach the professional soccer teams in the same proportion.

The Relative Age Effect based on playing-position and performance on Brazilian elite men’s basketball

The aim of this study was to verify the existence of RAE in Brazilian elite male basketball, considering athletes’ birth quartiles, playing positions, team placement, and tactical-technical performance in the Novo Basquete Brasil (NBB). A total of 454 male athletes were analyzed according to their birth quartiles, playing positions, final team placement in the championship, and tactical-technical performance. The goodness of fit chi-square test was used to compare the distribution of birth quartiles for the overall sample and based on playing positions and team final placements. The Kruskal-Wallis test was used to compare tactical-technical performance based on birth quartiles. Results indicated that athletes born in the last quartile of the year were less frequent than those born in the first (p &lt; 0.001), second (p &lt; 0.006), and third (p &lt; 0.001) quartiles of the year for the overall sample. Unequal distributions were also reported for the Small Forward position (p = 0.018). Regarding the final team placements, unequal distributions were observed for intermediate teams in the 2019/2020 season (p = 0.014), top teams in the 2020/2021 season (0.027), and bottom teams in the 2021/2022 season (p = 0.005). No association was found between RAE and any tactical-technical performance variable ( p &gt; 0.005). It is concluded that RAE was present in the NBB in Brazilian elite male athletes, but it does not seem to be a factor associated with collective nor individual tactical-technical performance. El objetivo de este estudio fue verificar la existencia del Efecto de Edad Relativa (RAE) en el baloncesto de élite masculino brasileño, considerando los cuartiles de nacimiento de los atletas, las posiciones de juego, la colocación del equipo y el rendimiento táctico-técnico en el Novo Basquete Brasil (NBB). Se analizaron un total de 454 atletas masculinos según sus cuartiles de nacimiento, posiciones de juego, colocación final del equipo en el campeonato y rendimiento táctico-técnico. Se utilizó la prueba de ajuste chi-cuadrado para comparar la distribución de los cuartiles de nacimiento para la muestra general y según las posiciones de juego y la colocación final del equipo. Se utilizó la prueba de Kruskal-Wallis para comparar el rendimiento táctico-técnico según los cuartiles de nacimiento. Los resultados indicaron que los atletas nacidos en el último cuartil del año fueron menos frecuentes que aquellos nacidos en el primer (p &lt; 0.001), segundo (p &lt; 0.006) y tercer (p &lt; 0.001) cuartil del año para la muestra general. También se informaron distribuciones desiguales para la posición de Ala (p = 0.018). Con respecto a la colocación final del equipo, se observaron distribuciones desiguales para equipos intermedios en la temporada 2019/2020 (p = 0.014), equipos mejores colocados en la temporada 2020/2021 (0.027) y equipos peores colocadas en la temporada 2021/2022 (p = 0.005). No se encontró asociación entre el RAE y ninguna variable de rendimiento táctico-técnico (p &gt; 0.005). Se concluye que el RAE estuvo presente en el NBB en atletas masculinos de élite brasileños, pero no parece ser un factor asociado con el rendimiento táctico-técnico colectivo ni individual. O objetivo deste estuo foi verificar a existência do Efeito da Idade Relativa (EIR) no basquetebol masculino de elite Brasileiro, considerando os quartis de nascimento, posições de jogo, colocação da equipe e desempenho tático-técnico de atletas do Novo Basquete Brasil (NBB). Foram analisados 454 atletas masculinos de acordo com seus quartis de nascimento, posições de jogo, colocação final da equipe no campeonato e desempenho tático-técnico. O teste qui-quadrado de ajuste foi utilizado para comparar a distribuição dos quartis de nascimento da amostra geral e de acordo com as posições de jogo e colocação final da equipe. O teste Kruskal-Wallis foi utilizado para comparar o rendimento tático-técnico de acordo com os quartis de nascimento. Os resultados indicaram que os atletas nascidos no último quartil do ano foram menos frequentes do que os nascidos no primeiro (p &lt; 0.001), segundo (p &lt; 0.006) e terceiro (p &lt; 0.001) quartis do ano para a amostra geral. Também foram apresentadas distribuições desiguais para a posição ala (p = 0.018). Em relação a colocação final da equipe, observou-se distribuições desiguais para as equipes intermediárias na temporada 2019/2020 (p = 0.014), equipes melhores colocadas na temporada 2020/2021 (0.027) e equipes piores colocadas na temporada 2021/2022 (p = 0.005). Não foram encontradas associações entre o EIR e nenhuma variável de desempenho tático-técnico (p &gt; 0.005). Conclui-se que o EIR está presente no NBB em atletas masculinos de elite Brasileiros, mas não parece ser um fator asociado com o desempenho tático-técnico coletivo e individual.

Performance trajectories of Italian professional cyclists: an analysis of the influence of youth performance on professional success

ABSTRACT The aim of the study was to analyse individual performance trajectories of professional (PRO) Italian cyclists across their careers. It sought to compare the performance progression of successful and unsuccessful PRO cyclists, analyse the best predictors of success in PRO cyclists and explore whether the relative age effect (RAE) influences PRO success. The national ranking positions gathered in the youth (U19 and elite/U23) and the PRO categories were retrieved for every year of competition of 81 PRO Italian cyclists and retrospectively analysed. Participants were divided in successful and unsuccessful, depending on whether they reached at least once the top 400 positions in the PRO ranking or not. Successful PRO cyclists display better youth ranking positions and tend to spend less time in youth categories, transition to the PRO category at an earlier age, reach their best PRO ranking at an older age compared to unsuccessful PRO cyclists. The best youth ranking, the age of the best PRO ranking and the years spent in youth categories are all predictors of PRO success. For every additional year spent in youth categories, there are 50.8% less odds of becoming a successful PRO cyclist. RAE does not affect Italian cyclists’ PRO success.

The relative age effect in selection of ab initio pilots–Revisiting Gladwell's famous claims

A relative age effect (RAE) has been found in education and sports, with students born earlier in the school year attaining higher levels of success. This was brought into public consciousness through Malcom Gladwell's Outliers: The Story of Success. However, the effect has not been thoroughly examined in other contexts. Thus, with regards to the context dependency of the RAE, and the specificity of which abilities it affects, there are unknowns. The aim of the present study was to scrutinize the tests in use in commercial aviation and explore whether there is a bias based on birthdate in competitive selection procedures assessing operational and cognitive abilities, outside of traditional education. Potential suboptimal selection has implications for flight safety. Associations were studied between relative age and test scores (of cognitive ability, manual spatial ability, and multitasking ability), as well as acceptance for higher education in commercial aviation in Sweden, in 1113 ab initio candidates. Relative age neither had a significant correlation with any of the six performance scores, nor with an aggregated factor score (r = −0.009, p = 0.791), nor predicted flight-school admission (b = 0.036, p = 0.210). Chronological age was associated with manual spatial ability, yet neither correlated with aggregate score nor with admission. The results may be an indication of the RAE having faded in early adulthood, and/or that indirect exposure of education does not benefit candidates in operational tests in early adulthood. Thus, neither relative age nor chronological age seemed to bias the results. For the effects of RAE to persist– or occur in operational abilities– competition between candidates in selection and subsequent relevant exposure (e.g., training/schooling), may be needed. Overall cognitive ability is likely more predictive of success when variance in specific enhancing exposure is limited.

A Hypothesis-Free Approach to Identifying Potential Effects of Relative Age in School Year: an Instrumental Variable Phenome-Wide Association Study in the UK Biobank.

A child's relative age within their school year ('relative age') is associated with educational attainment and mental health. However, hypothesis driven studies often re-examine the same outcomes and exposure, potentially leading to confirmation and reporting biases, and missing unknown effects. Hypothesis-free outcome-wide analyses can potentially overcome these limitations. We conducted a hypothesis-free investigation of the effects of relative age within school year. We used an instrumental variable (IV)-pheWAS in the UK Biobank (participants aged 40-69 years at baseline), using the PHESANT software package. We created two IVs for relative age: being born in September vs. August (n=64 075) and week of birth (n=383 309). Outcomes passing the Bonferroni-corrected P value threshold for either instrument were plotted to identify a discontinuity at the school year transition. 13 traits associated with at least one of the instruments showed a discontinuity. Previously identified effects included those with a younger relative age being less likely to have educational qualifications and more likely to have started smoking at a younger age. We detected a few associations not explored by previous studies. For example, those with younger relative age had better lung function as adults. Hypothesis-free approaches could help address confirmation and reporting biases in epidemiology.

Unveiling workplace safety and health empowerment: Unraveling the key elements influencing occupational injuries

Introduction: Millions of workers globally experience work-related injuries, leading to fatalities, injuries, job loss, and wider societal implications. This study utilizes both the U.S. database and the General Social Survey (GSS) to delve into the factors linked to occupational injuries. Methods: In this study, 30 questions from the GSS between 2002 and 2014 were used. The sample included 5,914 workers from various sectors, distributed between both female and male, and were of 18 years and above. The analysis encompasses several dimensions: demographics, job-related characteristics, administrative factors, and health and safety measures. The study particularly focuses on assessing the prevalence of three common work-related injuries: nonfatal injuries, back pain and arm pain. Logistic regression models were constructed to gauge the effects of identified factors. Results: Significant insights emerge from the analysis. Factors such as age, gender, race, working hours, overtime work, trust in management, coworker support, and workflow smoothness were identified as having notable impacts on work-related injuries. For each model, the study quantifies these impacts through odds ratio and relative effects. For example, in the nonfatal injuries model, the relative effects of age showed that workers aged 65 years or older experience a 2.56% decrease in the frequency of nonfatal injuries compared to younger workers. Furthermore, in the back pain model, the estimated odds of having back pain in males are 0.90 lower than that in females. Moreover, in the arm pain model, workers who have sufficient time to complete their tasks have estimated odds of experiencing arm pain that are 0.85 lower than those who don’t have adequate time, etc. Conclusions: Understanding the intricate interplay of various factors influencing workers’ safety and health is vital for addressing occupational injuries. By addressing these factors, there’s potential for reducing work-related injuries, enhancing work environment, and minimizing costs. Practical Applications: Organizations can use the study’s findings for reducing work related injuries. Flexible work arrangements, tailored training programs, and ergonomic improvements might highlight factors such as age, gender, and working hours. Enhancing communication, fostering a positive work culture, and prioritizing safety and health measures could reduce risks associated with trusting management and coworker support. Cost-benefit analysis and continuous monitoring ensure these interventions’ effectiveness, reduce back and hand pain incidents, minimize cost, and create safer workplaces, thereby boosting the overall well-being of workers and organizational success.

Chronological age, relative age, pubertal development, and their impact on countermovement jump performance in adolescent football players: An integrative analysis

This paper examined the relationship among countermovement jump (CMJ), football category, chronological age, relative age, and pubertal development status to investigate which parameter could be better associated with jumping performance. We tested 259 young male football players (14.9 ± 1.8 yrs; 169.7 ± 9.8 cm; 60.6 ± 11.3 kg; 20.9 ± 2.6 kg m−2) belonging to elite football academies. One-sample chi-square tests were used to test the uniformity of distributions of the proportions of players in each year quarter (relative age effect, RAE) for the whole sample and stratified for each football age category (U14, U15, U17, and U19). One-way ANOVAs were used to test the associations among a) categories, RAE, and CMJ, and b) the pubertal status category and CMJ. Pearson's correlation assessed the relationship among variables. The birth distribution among the year's quarters significantly differed from the expected proportion of 25 % of participants each quarter (χ2 = 41.74; p < 0.001), highlighting the presence of a relative age effect. Results indicate that age significantly influences CMJ (F(6,231) = 8.85, p < 0.001, η2p = 0.187), and a significant interaction effect (age × birth quarter) was found. Coaches, strength and conditioning trainers, and scouts should be aware of physical and biological players' maturation.

How to Compare Relative Age Effect in Different Sports? A New Methodological Approach-Example of Youth Olympic Games.

This research aimed to propose a new methodological approach for analyzing relative age effect (RAE) in different sports or samples named "Relative age effect overall scale" (RAEOS). The sample consisted of 1455 male and female young athletes who competed in four different sports (basketball, n = 159; handball, n = 215; swimming, n = 981; taekwondo, n = 100) at the Youth Olympic Games (YOG) in Buenos Aires in 2018. To construct the new model, the sample was classified into four unified quartiles of a specific range depending on the sport (swimming: 48-month range, taekwondo: 24-month range, and basketball and handball: 36-month range). Expected and observed frequencies for each sport, the winners/all athletes, and differences between team and individual sports were analyzed using a non-parametric Chi-square test. The obtained results confirm the existence of the RAE in all four analyzed sports (p > 0.01) in a sample of all participants and the sample of gold medalists. Differences between team and individual sports in the analyzed sample have also been found. The proposed methodological approach (RAEOS) is a simple and applicable tool that provides opportunities for comparison and analysis of different sports and competition formats, as well as improvement of the sports talent system in the context of RAE issues. It is suggested to the sports decision-makers to improve the YOG qualification and competition system to enable fairer competition and reduce the influence of RAE on the performance and development of young athletes.

Associations between Agility, the Relative Age Effect, Siblings, and Digit Ratio (D2:D4) in Children and Adolescents.

This study aims to analyze the influence of relative age effects, siblings, and digit ratio on the agility of children and adolescents. The study included 283 children (9.54 ± 1.36 years) and 296 adolescents (14.68 ± 1.36 years) from four different schools. The analyzed variables included anthropometric data, the presence of siblings, relative age effect, and results from the 10 × 5 m shuttle run test. The findings indicated no significant association between agility and either the 2D:4D ratio or the relative age effect in both children and adolescents (p > 0.05). Additionally, having siblings did not have a notable impact on agility. Multiple regression analysis confirmed that relative age did not influence this lack of association (quarter of birth: p = 0.345, β = 0.039; siblings: p = 0.100, β = -0.069). However, boys showed higher performance than girls in the 10 × 5 m shuttle run test, and higher body mass index was related to lower agility. These findings contribute to existing knowledge on the relative effects of age and provide valuable information for physical education teachers on the influence of the 2D:4D ratio and the presence of siblings on the physical fitness of children and adolescents.

Career trajectories, transition rates, and birthdate distributions: the rocky road from youth to senior level in men's European football.

This study aimed to assess youth-to-senior transition rates, quantify the magnitude of relative age effect (RAEs), and evaluate how RAEs affect these transitions in 9,527 men's national football players of England, France, Germany, Italy, and Spain. Regardless of national team, only -15%, 25%, and 40% of U17, U19, and U21 players successfully transitioned to the senior team, respectively, whilst -14%-24% progressed to senior level without being selected during youth. Data suggested a skewed birthdate distribution favouring relatively older players at U17, U19, and U21 levels across all countries, whereas RAEs were also present in England, Italy, and Spain at senior level. Youth-to-senior transition rates were modulated by birthdate at U17 and U19, whereby Q4 players were -2 and 1.5 times more likely to successfully transition at senior level than Q1 players, respectively. Selection at youth international level does not guarantee selection at senior level, but does make it more likely. Moreover, relatively younger athletes are disadvantaged in youth categories, although are more likely to transition to senior level once they have entered the pathway.

Relative age effect on national basketball teams around the world: Analysis by sex, age, location and world ranking

Relative age effect on national basketball teams around the world: Analysis by sex, age, location and world ranking

Selection and re-selection throughout a national talent pathway: Exploring longitudinal relative age effects in Northern Ireland male soccer

ABSTRACT The purpose of this study was to investigate the longitudinal prevalence of relative age effects (RAEs) across playing levels and positions in Northern Ireland international male soccer. Birthdates of U17 (n = 276), U19 (n = 320), U21 (n = 331), and senior (n = 108) international players between 2011 and 2023 were recorded. Chi-square tests and odds ratios with 95% confidence intervals were used to compare observed and expected birthdate distributions. A selection bias toward relatively older players was evident at U17 and U19 playing levels as well as defensive and midfield positions. In contrast, more relatively younger senior and forward players were selected. Longitudinal analyses revealed that of those players who were initially selected at U17, more relatively older players were re-selected at subsequent playing levels, but there were no birthdate asymmetries amongst new players added after U17. The results of this study demonstrate RAEs are prevalent across Northern Ireland international male soccer and are influenced by playing level as well as position. These findings have important implications for policy makers and practitioners as relatively older players are overrepresented at youth but not senior level, which questions the efficacy of this (un)conscious bias in the talent pathway.