Nick Wattie

Annual age-grouping and athlete development: a meta-analytical review of relative age effects in sport.

Annual age-grouping is a common organizational strategy in sport. However, such a strategy appears to promote relative age effects (RAEs). RAEs refer both to the immediate participation and long-term attainment constraints in sport, occurring as a result of chronological age and associated physical (e.g. height) differences as well as selection practices in annual age-grouped cohorts. This article represents the first meta-analytical review of RAEs, aimed to collectively determine (i) the overall prevalence and strength of RAEs across and within sports, and (ii) identify moderator variables. A total of 38 studies, spanning 1984–2007, containing 253 independent samples across 14 sports and 16 countries were re-examined and included in a single analysis using odds ratios and random effects procedures for combining study estimates. Overall results identified consistent prevalence of RAEs, but with small effect sizes. Effect size increased linearly with relative age differences. Follow-up analyses identified age category, skill level and sport context as moderators of RAE magnitude. Sports context involving adolescent (aged 15–18 years) males, at the representative (i.e. regional and national) level in highly popular sports appear most at risk to RAE inequalities. Researchers need to understand the mechanisms by which RAEs magnify and subside, as well as confirm whether RAEs exist in female and more culturally diverse contexts. To reduce and eliminate this social inequality from influencing athletes’ experiences, especially within developmental periods, direct policy, organizational and practitioner intervention is required.

The prevalence, influential factors and mechanisms of relative age effects in UK Rugby League.

Relative age effects (RAEs), reflecting observed inequalities in participation and attainment as a result of annual age‐grouping policies in youth sport, are common in most team sports. The aims of this study were to determine if and when RAEs become apparent in Rugby League, determine how influential variables (e.g., gender) lead and clarify whether player retention at junior representative levels can explain persistent RAEs. Player data were collected for the male and female community games ranging from Under 7s to Senior (N=15 060) levels, junior representative selections (i.e., Regional) and professional players (N=298). Chi‐square analyses found significant (P<0.05) uneven birth date distributions beginning at the earliest stages of the game and throughout into senior professionals. In junior representative selections, 47.0% of Regional and 55.7% of National representative players were born in Quartile 1, with RAE risk increasing with performance level. Gender and nationality were also found to moderate RAE risk. When tracking representative juniors, over 50% were retained for similar competition the following season. Findings clearly demonstrate that RAEs exist throughout Rugby League with early selection, performance level and retention processes, appearing to be key contributing factors responsible for RAE persistence.

Towards a unified understanding of relative age effects

Abstract When athletes are placed into annual age groups to organize and coordinate sport participation, certain (dis)advantages occur as a result of the subtle age differences within these groups. These differences, termed “relative age effects”, have been consistently related to youth and adult sport attainment. However, there has been a lack of consistency in the terminology used in this area of research. In this paper, we consider the operational terms used in relative age research, discuss appropriate applications of terminology, and suggest directions for future research. Importantly, we argue for a unified understanding of what “relative age” means, stressing the need for clarity in directing future advances in the field.

Circumstantial development and athletic excellence: The role of date of birth and birthplace

Abstract Researchers are only beginning to understand how contextual variables such as date of birth and birthplace affect the development of elite athletes. This article considers the generality of birthplace and date-of-birth effects in varying sport contexts. The Study 1 examined how environmental factors associated with an athletes date-of-birth and size of birthplace predict the likelihood of becoming an Olympic athlete in Canada, the United States of America, Germany, and the United Kingdom. Study 2 examined date-of-birth and birthplace effects among athletes playing in the first professional league in Germany. Study 2 also examined the validity of birthplace as a proxy for early developmental environment by comparing birthplace with the place of first sports club in four German sports leagues. Results from both studies showed no consistent findings for date of birth. Findings from Study 2 also suggested incongruence between birthplace and location of first sports club as proxies for early developmental environment. Although there was some consistency suggesting elite athletes are less likely to come from very small or excessively large communities, exceptions occurred both within and across sport contexts. These results suggest that any developmental effects of date and place of birth are buffered by broader socio-cultural factors.

Injuries in Canadian Youth Ice Hockey: The Influence of Relative Age

OBJECTIVE. The purpose of this study was to investigate the relationship between relative age and injury prevalence in Canadian youth ice hockey. METHODS. In study 1, youth ice hockey–related injuries (among children 10–15 years of age) collected by the Canadian Hospitals Injury Reporting and Prevention Program between 1995 and 2002 were analyzed. The relative ages of injured children were compared across different age groups and injury characteristics (mechanism of injury and severity of injury). In study 2, injuries reported in the Hockey Canada Insurance Database were analyzed. The relative ages of injured children at different levels of play (ie, representative versus house league teams) were compared. RESULTS. In study 1, the majority of injured players were of older relative age. However, relative age was not related to mechanism of injury or severity of injury. In study 2, ∼40% of injured players at the highest level of play were relatively older, whereas only 20% to 25% of house league injured players were relatively older. CONCLUSION. Relatively older children within ice hockey age groups are at increased risk of injury compared with their younger peers. Furthermore, the risk of injury for relatively older players is greater at more competitive levels of play. This study proposes that the relative age advantage associated with selection to Canadian youth ice hockey teams is accompanied by an increased risk of injury.

Season of birth and prevalence of overweight and obesity in Canada.

BACKGROUND The contexts of prenatal life, such as ones season of birth, have been shown to influence health later in life. For example, research has shown a disproportionate number of schizophrenic patients are born during the late winter and early spring. The purpose of this study was to examine season of birth as a possible risk for overweight and obesity. METHODOLOGY Utilizing cycle 2.1 of the Canadian Community Health Survey, birth data of respondents 12 to 64 years old were examined. The risk associated with season of birth was compared to risks previously identified for overweight and obesity (e.g. physical inactivity, low socioeconomic status etc.). RESULTS Overall, among the 20-64 year olds, those in the obese III (BMI> or =40 kg/m(2)) category were 1.54 times more likely to be born in the winter (95% CI: 1.21-1.95). This effect appears largely due to a winter/spring season of birth effect among the obese II/III (BMI> or =35) 20-29 y cohort (Winter OR: 1.53, 95% CI: 1.08-2.18; Spring OR: 1.55, 95% CI: 1.10-2.18). A summer season of birth effect was observed for the obese II/III 40-49 y cohort (OR: 1.59, 95% CI: 1.21-2.11). No season of birth effects were observed among any BMI categories for those 12-19 years, or among those 20 y and over in the overweight BMI category. CONCLUSION A greater proprtion of class III obese Canadians are born during the winter/spring, particularly in the 20-29 y age cohort. However, other factors (e.g. physical inactivity) represent greater risks for obesity than season of birth.

A New Dimension to Relative Age Effects: Constant Year Effects in German Youth Handball

In this manuscript we argue for a broader use of the term ‘relative age effect’ due to the influence of varying development policies on the development of sport expertise. Two studies are presented on basis of data from Schorer, et al. [1]. The first showed clear ‘constant year effects’ in the German handball talent development system. A shift in year groupings for the female athletes resulted in a clear shift of birth year patterns. In the second study we investigated whether the constant year effect in the national talent development system carried over to professional handball. No patterns were observable. Together both studies show that a differentiation of varying effects that often happen simultaneously is necessary to understand the secondary mechanisms behind the development of sport expertise.

Relative age-related participation and dropout trends in German youth sports clubs

Abstract Relative age describes a youths age within their age group cohort. Compared to relatively younger peers, relatively older youth in an annual age group cohort have been found more likely to be selected to sports teams, and to receive higher grades in education. This study examined the influence of youth sport participants’ relative age on participation and dropout. Using data from the 1995 German Youth Sport Survey (N total=2612), comparisons (stratified by gender and sport type) were made between the relative age of current and former participants. Analyses also considered the type of school youths were enrolled in while exploring the influence of relative age on sport participations. No relative age effects for dropout emerged among males in team or individual sport contexts. Female dropouts were more likely to be relatively older (Q1, ORadjusted: 0.52, 95% CI: 0.34–0.80; Q2, ORadjusted: 0.55, 95% CI: 0.36–0.84; Q3, ORadjusted: 0.59, 95% CI: 0.39–0.89), an effect that was mirrored among ‘artistic’ sport participants. Boys and girls in schools that were for children of higher academic proficiency were more likely to be currently participating in sport. Findings suggest that relative age-related dropout effects may be context sensitive and different for males and females. For the most part, relative age did not appear to have any relationship with dropout in this sample, with some notable exceptions for females. Overall, factors such as the type of school youths were enrolled in appear to be a more salient influence on sport participation than relative age.

Compromising Talent: Issues in Identifying and Selecting Talent in Sport

ABSTRACT The past few decades have seen a significant change in the delivery of sport and in trends related to athlete development. However, the notion of talent continues to play a critical role in most athlete development models. In this brief review, we highlight concerns with the notion of talent and how it is conceptualized in high performance sport systems. These include: the assumption that talent is a fixed capacity that can be identified early, the influence of talent beliefs on athlete development, the different levels of risk for talent selection decisions, biases evident in approaches to athlete selection, the inadequacy of current statistical approaches, the problems with using current performance to predict future outcomes, and how short-term priorities and competition between sports for talented athletes undermine the overall efficiency of athlete development systems. These concerns form the basis for more focused discussion of avenues for future work in this field.

No Link Between Date of Birth and ADHD Symptoms in Adults

Objective: Research has highlighted several negative consequences for individuals born in the later part of the academic year, including increased likelihood of being diagnosed with learning disabilities. In this study, we considered whether birthdate predicted ADHD symptomatology using two well known mechanisms, the relative age effect (RAE) and the season of birth effect (SOBE). Methods: Study participants completed two ADHD measures: Conners Adult ADHD Rating Scales (CAARS) and the Wender Utah Rating Scale (WURS). Results: There were gender effects in the WURS data indicating that males scored higher than females on ADHD symptoms as well as a significant interaction in the CAARS data to support differential patterns among males and females. Conclusion: Overall, results did not support a RAE or SOBE among males or females. Possible reasons for these findings and their implications are discussed.