THE RELATIVE AGE EFFECT IN COMBAT SPORTS: AN ANALYSIS OF OLYMPIC JUDO ATHLETES, 1964-2012

Relative age effect in elite Brazilian athletes in different combat sports: an observational study

Background

The relative age effect (RAE) suggests that, due to maturity, young athletes born in the first quartiles of the year may have advantages over those born in the last quartiles of the year. Thus, it is important to evaluate the RAE in different sports and to consider the particularities of the subdivisions of the sports categories.

Objective

To analyze the RAE in the top 20 of the Brazilian rankings in different combat sports.

Methods

Observational study that analyzed the national databases for the year 2019 (from categories U-11 to U-18) made publicly available by the Brazilian confederations of karate, taekwondo and fencing. We obtained data on date of birth, age category and body weight of all modalities, type of fencing competition weapon (Epee, Foie and Saber) and type of karate modality (kumite and kata) from the top 20 places in each ranking. The final sample consisted of 1,486 athletes (Age: 14.2 ± 2.3. Male-53.2%. Female-46.8%). To identify the RAE, we performed a contingency analysis and compared the results between the sexes within the same sport.

Results

There was RAE in the U-11, U-12, U-15 and U-17 fencing categories (p < 0.05), being higher in the female categories (p < 0.05). The RAE was higher for males in the Epee test, and similar between the sexes for the Saber and Foie tests. In karate, RAE occurred in categories U-14 and U-16 (p < 0.05), being higher in males (p < 0.05). The RAE was similar between the sexes in the kumite modality (p < 0.05). There was no RAE for the kata modality in karate (p > 0.05) and for the Taekwondo categories (p > 0.05).

Conclusion

The results showed the existence of a relative age effect in elite athletes ranked (top 20 places in each ranking) only for the sport of fencing and karate kumite.

Graphical abstract

Relative and Chronological Age in Successful Athletes at the World Taekwondo Championships (1997-2019): A Focus on the Behaviour of Multiple Medallists

The aims of this study were to investigate the relative and chronological age among taekwondo world medal winners (by gender, Olympic 4-year period, Olympic weight category; N = 740), and to study the behaviour of multiple medallists (N = 156) to monitor changes in weight categories and wins over time. The observed birth quartile distribution for the heavyweight category was significantly skewed (p = 0.01). Female athletes (22.2 ± 3.5 years) achieve success at a significantly younger age (p = 0.01) than their male counterparts (23.6 ± 3.3 years). In the weight categories, female flyweights were significantly younger than those welterweights (p = 0.03) and heavyweight (p = 0.01); female featherweights were significantly younger than those heavyweights (p = 0.03). Male flyweights and featherweights were significantly younger than those welterweights and heavyweights (p = 0.01). When a taekwondo athlete won a medal several times, he/she did so within the same Olympic weight category group and won two medals in his/her career (p = 0.01). Multiple medallists of the lighter and heavier groups did not differ in the number of medals won but in the time span in which they won medals (p = 0.02). The resources deployed by stakeholders to achieve success in these competitions highlight an extremely competitive environment. In this sense, the information provided by this study can be relevant and translated into key elements.

The relative age effect in young athletes: A countywide analysis of 9-14-year-old participants in all competitive sports

The relative age effect (RAE) has primarily been investigated in male athletes involved in popular sports and high-level competitions. However, occurrence of RAE in other types of sports at the grassroots level, particularly in female athletes, is less well-studied. Thus, we examined the RAE in a large cohort of young athletes who participated in all competitive sports in Bizkaia, Spain, according to gender and specificity of the sport. The birth dates of 38,381 participants (65.1% males and 34.9% females) aged 9–14 years old in 37 competitive sports were analyzed. Birth dates were divided into four birth-quarters and compared to those of all children born in the same period using a χ² goodness-of-fit test and standardized residuals. The effect size Cramer’s V was measured, and odds ratio and 95% confidence intervals were calculated to determine the odds of athletes born in January playing in the highest leagues. In the total sample, in boys RAE was evident in football, but only in higher-competition leagues (p<0.001, large effect size). In girls, RAE was evident in the most popular team sports: basketball (p<0.001, large effect size in basketball 1^st league), handball and football (p<0.05, both small effect sizes). Players born in January were 3.23- and 2.89-times more likely to play in the 1^st leagues than those born in December, for boys (football) and girls (basketball) respectively. In the overall analysis and in the remaining sports, presence of RAE was negligible. Therefore, the date of birth does not seem to be a constraint to participating in most sports in Bizkaia. The potential mechanisms for RAE are multifactorial and complex, yet a combination of factors, such as the popularity of a sport and the depth of competition, physicality and social influences may be involved. We discuss these mechanisms and potential measures to mitigate RAE.

Inequality in Brazilian basketball: the birthplace effect

abstract This study aimed to investigate the birthplace effect in Brazilian basketball athletes of both sexes according their states and geographical regions. Our hypothesis is that the São Paulo (SP) state is the leading player in the Southeastern region and stands out from the other regions. The birthplace of Brazilian athletes participating in the FIBA World Cup and in two national leagues were collected from open-access websites. Three hundred and fifteen athletes’ birthplaces were included. The absolute and relative frequencies of athletes’ birthplaces per state and geographical region were calculated. Chi-Square tests were used to compare the expected and the observed frequencies of birthplaces among regions and states. Odds Ratios and 95% confidence intervals were calculated to indicate the probability of a high-level athlete to be born in a certain region or state. The results completely confirmed our hypothesis, showing higher frequencies of athletes born in the Southeastern region, especially in the SP state. We concluded that the uneven participation in basketball in Brazil is caused by the continental dimensions of the country and the modality historical context. Concentrating basketball clubs on a single region or state (SP) leads to an underuse of the sporting potential in the country.

Physical Performance in Young Judo Athletes: Influence of Somatic Maturation, Growth, and Training Experience

Purpose: To determine the individual contributions of chronological age, somatic maturation, body size and composition, and training experience as indicators of performance in neuromuscular and judo-specific assessments in young athletes. Methods: Sixty-six youth judo athletes performed anthropometric measurements, neuromuscular tests-standing long jump test (SLJ), medicine ball throw test (MBT), handgrip strength test (HGS), and judo-specific tests-Special Judo Fitness test (SJFT) and Judogi Grip Isometric Strength Test (JGST_ISO). A multiple linear regression was used with the level of significance set at 5%. Results: The main results showed age-peak height velocity (PHV), body fat and training experience explained close to 20% of SJFT performance. Chronological age, age-PHV, height, body mass and body fat accounted for 42% of variance in JGST_ISO. Chronological age, body fat and training experience explained 35% of the variance in SLJ, while chronological age, body mass and body fat explained 53% of the variance in MBT. Finally, age-PHV, body mass and height explained 54% of the variance in HGS. Conclusion: Estimated age-PHV and growth variables explained moderate to large proportions of the variance in neuromuscular tests (with exception of SLJ), while both estimated age-PHV, training and growth variables were predictors of judo-specific performance.

Effects of Bio-Banding upon Physical and Technical Performance during Soccer Competition: A Preliminary Analysis

Bio-banded competition has been introduced to address the variation in physical maturity within soccer. To date, no research has investigated the effect of bio-banded competition relative to chronological competition. The current study investigated the effect of bio-banding upon physical and technical performance in elite youth soccer athletes. Twenty-five male soccer athletes (11–15 years) from an English Premier League soccer academy participated in bio-banded and chronological competition, with physical and technical performance data collected for each athlete. Athletes were between 85–90% of predicted adult stature, and sub-divided into early, on-time and late developers. For early developers, significantly more short passes, significantly less dribbles and a higher rating of perceived exertion (RPE) were evident during bio-banded competition compared to chronological competition (p < 0.05). Significantly more short passes and dribbles, and significantly fewer long passes were seen for on-time developers during bio-banded competition (p < 0.05). For late developers, significantly more tackles, and significantly fewer long passes were evident during bio-banded competition (p < 0.05). No significant differences in physical performance were identified between competition formats. Results demonstrated that bio-banded competition changed the technical demand placed upon athletes compared to chronological competition, without reducing the physical demands. Bio-banded competition can be prescribed to athletes of differing maturation groups dependent upon their specific developmental needs.

Characteristics of Relative Age Effects and Anthropometric Data in Japanese Recreational and Elite Male Junior Baseball Players

BACKGROUND

The mechanisms underlying the relative age effect (RAE), a biased distribution of birth dates, in sport events have been investigated for more than two decades. The present study investigated the characteristics of the RAE in baseball and anthropometric data (height and weight) among recreational junior baseball players as well as elite players, using data extracted from national surveys.

METHODS

Birth and anthropometric data were obtained from 4464 Japanese students as elementary school, junior high school, and high school players.

RESULTS

Significant RAEs were noted in recreational junior high school and high school players, but not in elementary school players, and the effect size became larger with increasing grade (0.063 in elementary school players, 0.151 in junior high school players, and 0.227 in high school players). We also observed a significant RAE for elite elementary, junior high, and high school players. However, the effect size of elite players became smaller with increasing grade (0.563 in elementary school players, 0.358 in junior high school players, and 0.343 in high school players). Height and weight values were significantly larger in elite elementary and junior high school players than in recreational elementary and junior high school players, but height was almost the same between recreational and elite high school players.

CONCLUSION

The characteristics of RAEs differed between recreational and elite junior baseball players. Anthropometric data were also different, depending on birth data, and between recreational and elite baseball players in elementary and junior high school students.

Relative Age Effects Across and Within Female Sport Contexts: A Systematic Review and Meta-Analysis

BACKGROUND

Subtle differences in chronological age within sport (bi-) annual-age groupings can contribute to immediate participation and long-term attainment discrepancies; known as the relative age effect. Voluminous studies have examined relative age effects in male sport; however, their prevalence and context-specific magnitude in female sport remain undetermined.

OBJECTIVE

The objective of this study was to determine the prevalence and magnitude of relative age effects in female sport via examination of published data spanning 1984-2016.

METHODS

Registered with PROSPERO (No. 42016053497) and using Preferred Reporting Items for Systematic Reviews and Meta-analysis systematic search guidelines, 57 studies were identified, containing 308 independent samples across 25 sports. Distribution data were synthesised using odds ratio meta-analyses, applying an invariance random-effects model. Follow-up subgroup category analyses examined whether relative age effect magnitudes were moderated by age group, competition level, sport type, sport context and study quality.

RESULTS

When comparing the relatively oldest (quartile 1) vs. youngest (quartile 4) individuals across all female sport contexts, the overall pooled estimate identified a significant but small relative age effect (odds ratio = 1.25; 95% confidence interval 1.21-1.30; p = 0.01; odds ratio adjusted = 1.21). Subgroup analyses revealed the relative age effect magnitude was higher in pre-adolescent (≤ 11 years) and adolescent (12-14 years) age groups and at higher competition levels. Relative age effect magnitudes were higher in team-based and individual sport contexts associated with high physiological demands.

CONCLUSION

The findings highlight relative age effects are prevalent across the female sport contexts examined. Relative age effect magnitude is moderated by interactions between developmental stages, competition level and sport context demands. Modifications to sport policy, organisational and athlete development system structure, as well as practitioner intervention are recommended to prevent relative age effect-related participation and longer term attainment inequalities.

Relationship Between the Relative Age Effect and Lengths of Professional Careers in Male Japanese Baseball Players: a Retrospective Analysis

BACKGROUND

The mechanisms underlying the relative age effect in sport events have been investigated for more than two decades. The present study focused on the relationship between the relative age effect and lengths of professional careers among professional male Japanese baseball players.

METHODS

The birth dates of players and lengths of professional careers were collected from an official publication, and data were divided into four quarters (Q1: April-June; Q2: July-September; Q3: October-December; Q4: January-March of the following year) grouped by 3 years. Based on the data for Q4, the expected numbers for the lengths of professional careers were calculated for Q1, Q2, and Q3.

RESULTS

The number of players with professional careers of more than 19 years was significantly smaller in Q4 than in Q1, Q2, and Q3.

CONCLUSIONS

The relative age effect among professional male Japanese baseball players was associated with the lengths of professional careers. Relative age appears to be a very important factor for the development of expertise among male Japanese baseball players and involves long-term disadvantages after becoming professional players.

Relative Age Effect in Physical Fitness Among Elementary and Junior High School Students

The present study investigated characteristics of the relative age effect (RAE) among a general sample of Japanese elementary and junior high school students. Japan applies a unique annual age-grouping by birthdates between April 1 and March 31 of the following year for sport and education. Anthropometric and physical fitness data were obtained from 3,610 Japanese students, including height, weight, the 50-m sprint, standing long jump, grip strength, bent-leg sit-ups, sit and reach, side steps, 20-m shuttle run, and ball throw. We examined RAE-related differences in these data using a one-way analysis of variance by comparing students with birthdates in the first (April-September) versus second (October-March of the following year) semesters. We observed a significant RAE for boys aged 7 to 15 years on both anthropometric and fitness data, but a significant RAE for girls was only evident for physical fitness tests among elementary school and not junior high school students. Thus, a significant RAE in anthropometry and physical fitness was evident in a general sample of school children, and there were RAE gender differences among adolescents.

Relative Age Effect in Mind Games: The Evidence from Elite Chess

Numerous studies have attempted to investigate the factors affecting superior intellectual performance, and it has been proposed that a possible biological marker for superior intellectual performance is the month of birth. In this study, birth details of chess players were obtained from the official international chess federation website. The rating lists of top junior female chess players ("Girls" category), top junior male chess players ("Boys"), top female chess players ("Female"), and top male chess players ("Male") were collected between July 2000 and August 2015. The birth months of each player that appeared in the top rating list were categorized into quarters. Additionally, relative age of chess players was calculated. Results supported the existence of the relative age effect in chess in all categories although a "reverse" RAE was found in the "Male" category.

Premier League academy soccer players' experiences of competing in a tournament bio-banded for biological maturation

Individual differences in the growth and maturation have been shown to impact player performance and development in youth soccer. This study investigated Premier League academy players' experiences of participating in a tournament bio-banded for biological maturation. Players (N = 66) from four professional soccer clubs aged 11 and 14 years and between 85-90% of adult stature participated in a tournament. Players competed in three 11 vs 11 games on a full size pitch with 25-min halves. Sixteen players participated in four 15-min focus groups and were asked to describe their experiences of participating in the bio-banded tournament in comparison to age group competition. All players described their experience as positive and recommended the Premier League integrate bio-banding into the existing games programme. In comparison to age-group competitions, early maturing players described the bio-banded games more physically challenging, and found that they had to adapt their style of play placing a greater emphasis on technique and tactics. Late maturing players considered the games to be less physically challenging, yet appreciated the having more opportunity to use, develop and demonstrate their technical, physical, and psychological competencies. Bio-banding strategies appear to contribute positively towards the holistic development of young soccer players.