Relative Age Effect in Brazilian water polo: analysis of male and female athletes from U16 to senior categories

Abstract Aim: To investigate the existence of relative age effect (RAE) in Brazilian water polo athletes according to sex and age category. Methods: The birthdate of 574 Brazilian water polo athletes were organized according to the athletes' birthdates into quarters of the year (Q1, Q2, Q3, and Q4), and classified according to sex (male and female) and age category (U16, U18, U20, and senior). To verify the existence of RAE, the Chi-Square tests (χ2) were performed, and the effect sizes (ω) were calculated for each of the tests. We also calculated odds ratio (ORs) and 95% confidence intervals, setting the level of significance to 0.05. As post hoc analysis, multiple comparisons between quarters were performed, with Bonferroni's correction (significance level set to 0.0083 in these cases). Results: The results indicated an uneven distribution of birthdates for male water polo athletes (χ2 = 12.257; p = 0.007; ω = 0.173), with an overrepresentation of athletes born in the first (p < 0.006) and second (p < 0.002) quarters. When sex and age category were considered, male athletes presented uneven distributions in U20 (χ2 = 10.747; p = 0.013; ω = 0.345) and senior (χ2= 12.614; p = 0.006; ω = 0.383) categories. In females, no differences were found. Conclusion: We conclude that there is an uneven distribution of birthdates in male Brazilian water polo athletes, indicating the presence of RAE in this group.

Relative Age Effect on Brazilian male elite futsal athletes according to playing position and performance by goals scored on Brazil National Futsal Leagues

Abstract Introduction: The relative age effect is prevalent in different elite team sports. However, little is known about this phenomenon in high-level adult male futsal players. Aim: The present study aimed to investigate the prevalence of relative age effect in Brazilian male elite futsal players, and its relationship with playing position and goals scored on Brazil National Futsal Leagues (BNFL) from 2016 to 2020. Methods: The distribution of birth dates, playing positions, and goals scored by male participants of the Brazil National Futsal Leagues were analyzed. Chi-squared tests were used to analyze the birth dates distribution based on quarters and semesters of the year, according to playing position (defender, winger, pivot, and goalkeeper) and scoring performance (high and low). Results: The overall analysis indicated that the relative age effect is prevalent on the pool of athletes analyzed. However, this effect was position-dependent, since relatively older athletes were overrepresented only in wingers and defenders playing positions. On the other hand, scoring performance was not associated with the relative age effect, since this effect was found in both performance levels. Conclusion: Relative age effects are prevalent in Brazilian male elite futsal athletes, especially for defenders and wingers. Considering the high level of competitiveness for spots in elite futsal teams, coaches and sports administrators must be educated about the prevalence of the relative age effect in this sporting context. This is necessary in order to reduce the inequalities generated by age categories based on arbitrary cut-off dates, which may reduce potential talent loss.

Relative age effect, skeletal maturation and aerobic running performance in youth soccer players

To investigate the presence of a relative age effect (RAE) and the influence of birth quarters (BQ), semesters (S) as well as skeletal maturation on anthropometric characteristics and aerobic peak speed (PST-CAR) in youth male soccer players. Methods: One hundred players were recruited to participate in this study. Players were allocated into 4 BQ's and 2 S. Skeletal maturity status was assessed using the Fels method. Assessments for players included determination of body size and composition and PST-CAR. Results: Overall, more players were born in BQ1 (38 %) and S1 (75%). The likelihood of players born in BQ1 and BQ2 being selected was 3.61 to 4.96 times higher than players in BQ3 and BQ4. Players in BQ4 maturing earlier were biologically older than their peers in BQ1. The players in BQ3 and S2 displayed higher PST-CAR compared with players in BQ2 and S1, respectively. However, players of contrasting skeletal maturity status did not differ in aerobic performance. Conclusion: Our findings indicate that coaches and talent scouts are systematically retaining average and early maturing players born in S1 and excluding late maturing players born in BQ4. However, aerobic performance appeared to be dependent on the relative age, but independent of skeletal maturation during puberty.(AU)

Clinical analysis of the delivery date reckoned by traditional and modified formula for calculating the expected date of confinement / 解放军医学杂志

Objective To analyze the difference of the delivery date reckoned by traditional and modified formula for calculating the expected date of confinement (EDC).Methods The data of 2055 women (37-41+6 week) were collected who gave monotocousa term spontaneous birth in the Chongqing Health Center for Women and Children from Jan.2014 to Feb.2015.Of which 1300 were primipara,and 755 were multipara;and the data of 1224 women (39-41week) were collected,of which 832 were primipara,and 392 were multipara.The expected date was calculated with traditional and modified calculating formula,and then the actual delivery date was used for comparison and statistical analysis.Results The coincidence of actual delivery date with the estimated due date reckoned by traditional formula (39-41week) was 8.4％ in primipara and 9.7％ in multipara,and the coincidence reckoned by modified formula was 11.9％ in primipara and 14.8％ in multipara.The EDC estimated by modified formula was more precise than that calculated by traditional formula (P＜0.05).Conclusion The EDC calculated with modified formula is more accurate than that calculated with traditional formula.

Efeito da idade relativa nas categorias do futebol brasileiro: critérios de seleção ou uma tendência populacional? / The relative age effect on the categories of Brazilian soccer: selection criteria or a population trend? / Efecto de la edad relativa en futbolistas de la cantera en el fútbol brasileño: ¿criterios de selección o tendencia de la población?

Resumo O objetivo deste estudo consistiu em comparar a frequência de datas de nascimento entre atletas de futebol e a população brasileira e verificar possíveis diferenças entre categorias. Participaram 868 atletas avaliados entre 2001 a 2009, pertencentes às categorias sub-15, sub-17, sub-20 e profissional. As datas de nascimento foram classificadas por trimestres. Usou-se o teste qui-quadrado para análise, adotou-se P < 0,05. Houve diferença significativa entre os quartos de ano, com tendência a nascimentos no primeiro semestre, similar à distribuição da população brasileira. Não foram identificadas diferenças significativas entre as categorias. Concluiu-se que há uma tendência de nascidos no início do ano que desfavorece possíveis talentos nascidos no fim do ano competitivo.

Abstract The purpose of this study was to compare the birth dates of soccer players and the Brazilian population as well as assess possible differences among categories. 868 players participated in this study, distributed according to the U-15, U-17, U-20 and professional categories. The birth dates were classified by quartiles. The chi-square test was used for the analyses, considering P < 0.05. Significant difference was identified among quartiles of births with a tendency to births in the first half, similar to the distribution of the Brazilian population. No differences were significant among categories. It was concluded that there is a tendency for births in the beginning of the year, discouraging potential talent ones who were born at the end of the competitive year.

Resumen El objetivo de este estudio fue comparar la frecuencia de las fechas de nacimiento entre jugadores de fútbol y la población brasileña, e investigar las posibles diferencias entre categorías. Participaron 868 jugadores nacidos entre 2001 y 2009, y pertenecientes a las categorías sub-15, sub-17, sub-20 y profesional. Las fechas de nacimiento se clasificaron por trimestres. Se utilizó la prueba de chi cuadrado y se utilizó el valor de P < 0,05. Hubo diferencias significativas entre los diferentes cuatrimestres, con tendencia al nacimiento en el primer semestre, de forma similar a la distribución de la población brasileña. No hubo diferencias significativas entre las categorías. Se concluye que existe una tendencia de nacimientos a principios de año, lo cual trae consigo una desventaja para aquellos posibles talentos que nacen a finales del año competitivo.

Relative age effect in fifa u17 emirates 2013 world cup: analysis of players who effectively participated in the matches / Efeito da idade relativa na copa do mundo fifa sub-17 emirates 2013: análise de jogadores que efetivamente participaram nos Jogos / Efecto de la edad relativa en la copa mundial de fútbol sub-17 emiratos 2013: análisis de los jugadores que participaron efectivamente en los partidos

The purpose of this study was to verify the date of birth is a decisive factor for the success of players selected by the coaches to participate in the FIFA U-17 World Cup Emirates 2013. The players' date of birth were classified into four quartiles of three months each (Q1 to Q4). In the qualifying round, 46.5% of the selected players born in Q1, while 12.5% in Q4. This significantly different distribution occurred until the semi-finals. However, in the final match, there were no significant differences between Q1 and Q4. A similar relative age effect also occurred when analyzed only players who actually participated to the matches. Interestingly, despite there was birth date effect on performance in all World Cup stages except in the final, other issues should take into consideration for a team became champion.

O objetivo deste estudo foi verificar se a data de nascimento é um fator decisivo para o sucesso de jogadores selecionados pelos treinadores para participar da Copa do Mundo Sub-17 Emirates 2013. As datas de nascimento dos jogadores foram classificadas em quatro quartis de três meses de cada (Q1 a Q4). Na qualificação, 46,5% dos jogadores selecionados nasceram em Q1, enquanto 12,5% em Q4. Esta distribuição significativamente diferente ocorreu até às semifinais. Entretanto, na final, não houve diferenças significativas entre Q1 e Q4. Um efeito similar da idade relativa também ocorreu quando analisados apenas os jogadores que efetivamente participaram das partidas. Curiosamente, apesar de haver efeito da data de nascimento sobre o desempenho em toda Copa do Mundo, exceto na final, outras questões devem levadas em consideração para uma equipe sagrar-se campeã.

La finalidad de este estudio fue verificar la fecha de nacimiento es un factor decisivo para el éxito de los jugadores seleccionados por los entrenadores para participar de la Copa Mundial sub-17 FIFA Emirados Árabes Unidos 2013. Fecha de nacimiento se clasificaron en cuatro cuartiles de tres meses (Q1 a Q4). En la qualificación, 46,5% de los seleccionados nacieron en Q1, mientras 12,5% en Q4. Esta distribución diferente ocurrió hasta las semifinales. Sin embargo, en la final, no hubo diferencias entre Q1 y Q4. Un efecto similar también ocurrió cuando se analizaron sólo los jugadores que efectivamente hugaron. Curiosamente, mismo con efecto de la fecha de nacimiento en toda la Copa Mundial, excepto la final, otros temas deben tener en cuenta para un equipo hacerse campeón.

Ultrasonographic factors related with prediction of delivery day in term singleton pregnancy / 대한산부인과학회지

OBJECTIVE: The aim of this study was to find out the relating factors with the actual delivery day in term singleton pregnancy. METHODS: The 52 patients with singleton gestation were visited weekly and measured for their lower uterine segment (LUS) thickness, cervical length and cervical gland thickness by transvaginal ultrasonography and for amnionic fluid index (AFI) by transabdominal ultrasonography from 36 weeks of gestation until birth. Regression analysis was used to find out the relevance between these factors and remaining days to birth. RESULTS: There was a significant relationship between cervical length and remaining days to birth in term pregnancy, which could be described as a mathematical equation (remaining days for delivery = 6.12 + 0.24 x cervical length (mm) r=0.29, p<0.01). However, no relationship was found between factors such as LUS, AFI, and cervical gland thickness and remaining days to birth. CONCLUSION: Our results suggest that the actual delivery day in term singleton pregnancy might be predicted with cervical length.

Birth Registration Rate and Accuracy of Reported Birth Date in Rural Area / 예방의학회지

To measure the birth registration rate and the validity of birth registration data in rural area, all of the 4,014 married women under 49 years of age who had not been sterilized in Gunwee county of Kyungpook province were followed by Myun health workers for 2 years from April 1, 1985 to March 31, 1987 and 766 births were detected. All of the birth registration records of Myun offices were reviewed on September 30, 1987 and 944 births which occurred within the above mentioned period were found. Actual birth date obtained by follow-up study were compared with the birth date on registration card. Among 766 births detected by follow-up study, 576 births(75.2%) which were reported within 6 months after birth were ascertained on the official registration records and 96 births(12.5%) were not found on the records although mother stated that the birth was registered. The registration rate within legal due date was 61.3% among 576 births detected by follow-up study and also ascertained on the official records. The registration rate within legal due date was lower in mothers under 20 years of age and above 35 years and in mothers who had only primary education. It was decreased as the birth order increased. The registration rate was higher in births occurred from October to March than births occurred from April to September. All of the births of 7 neonatal deaths were not reported. The registered birth date was consistent with the actual birth date in 78.0%. Birth date on record was earlier than the actual birth date in 6.8% and later in 15.3%. The consistency rate was lower in mothers above 35 years of age(54.5%), and in infants of 4th birth order and above(56.3%). The rate was increased as the maternal education level increased. The rate of boys was higher than that of girls. A higher percentage(17.4%) of infants born in March was registered with earlier date than the actual birth date and most of these registered birth dates were lunar calendar date. This might be related with the age for entering the primary school. The study findings revealed that the birth registration rate within legal due date and accuracy of report have been increased in recent years, but the infant mortality rate derived from the birth registration seems to be very inaccurate. It is suggested to let the medical personnel who delivered the baby report the birth by mail directly to the current address of parent while infants delivered at home without professional attendant may comply with the present registration system.