Vivian de Oliveira

Background: Reduced sleep quality is associated with impaired emotional functioning. This study examined whether emotion suppression was involved in cross-sectional indirect associations between three sleep-related components – subjective sleep quality, habitual sleep efficiency, and daytime dysfunction – and mental toughness in combat sports athletes. Methods: Ninety male combat sports athletes – aged between 18 and 34 years ( M = 25.26) – completed the Pittsburgh Sleep Quality Index (PSQI), the Courtauld Emotional Control Scale (CECS), and the Sport Mental Toughness Questionnaire (SMTQ). To examine cross-sectional associations through emotion suppression between the three analyzed sleep components and athletes’ mental toughness, indirect association analyses were conducted. Results: Significant cross-sectional indirect associations through depressive emotion suppression were observed between each of the three sleep components – subjective sleep quality, habitual sleep efficiency, and daytime dysfunction – and mental toughness. No statistically significant indirect associations through either anger or anxiety were observed. Conclusion: The findings suggest that depressive emotion suppression may be relevant to the relationship between sleep-related functioning and mental toughness in combat sports athletes. This highlights the potential importance of considering emotional functioning alongside sleep-related factors when examining mental toughness in this population.

This study examined birth-quarter patterns across competitive categories in group rhythmic gymnastics, their associations with morphological characteristics, and whether team-level relative-age composition, chronological age, and height were associated with competitive success. The sample comprised 241 female gymnasts from the 2025 Brazilian Group Rhythmic Gymnastics Championship: Pre-Juvenile (n = 68), Youth (n = 51), Junior (n = 62), and Senior (n = 60). Birth dates were classified into quarters (Q1–Q4), and anthropometric measures included body mass, standing and sitting height, leg length, and body mass index. Birth-quarter distributions were compared with population-based expected frequencies derived from Brazilian female live-birth data and weighted by birth year. Morphological associations were tested using generalized estimating equations clustered by club and adjusted for competitive category and decimal age. Exploratory associations with Top-3 success were assessed using conditional logistic regression stratified by competitive event. No category showed a significant departure from the population-based expected birth-quarter distribution after multiplicity adjustment (Holm-adjusted p ≥ 0.251), and the ordinal trend in first-semester representation was nonsignificant (OR = 0.799, 95% CI 0.637–1.000, Holm-adjusted p = 0.251). No morphological outcome remained significantly associated with birth quarter after adjustment for within-club dependence and multiple testing (Holm-adjusted p ≥ 0.083). Exploratory team-level associations with Top-3 placement were nonsignificant and imprecise (Holm-adjusted p = 1.000). Overall, the study found no statistically supported evidence of birth-quarter asymmetry or team-level associations with competitive performance, although imprecision precludes excluding potentially meaningful team-level effects.

The present study aimed to examine whether self-esteem acts as a mediator in the relationship between problematic internet use (PIU) and well-being among athletes, and to determine the implications of these relationships for educational practice, coaching strategies, and athlete support interventions. A total of 334 Polish athletes participated in the study and completed the Polish versions of the Generalized Problematic Internet Use Scale 2 (GPIUS2), the Rosenberg Self-Esteem Scale (SES), and the Mental Health Continuum-Short Form (MHC-SF). Pearson’s r correlation coefficients and mediation analyses using a bootstrap approach were conducted. The main results showed that PIU was negatively associated with self-esteem and well-being, whereas self-esteem was positively associated with well-being. Statistically significant, although small, indirect associations through self-esteem were observed between PIU and general well-being, as well as between all dimensions of PIU and emotional and psychological well-being. For social well-being, statistically significant indirect associations were observed only for preference for online social interaction and deficient self-regulation. These findings suggest that self-esteem may represent one psychological factor associated with the interrelations between PIU and well-being in athletes. The results may contribute to a more cautious understanding of the links between problematic internet use, self-esteem, and well-being, and may inform psychoeducational and preventive strategies in sport settings while acknowledging the limited practical significance of the observed effects.

Background: Monitoring health-related variables across a competitive season is essential to understand factors associated with performance in Paralympic athletes. However, evidence on the interplay between sleep, mood states, nutritional factors, injuries, and performance remains limited. Objective: To examine the associations between injuries, sleep parameters, nutritional factors, mood states, and performance in Para powerlifting athletes during a competitive cycle. Methods: Twenty-four athletes from the Brazilian National Para powerlifting team were assessed at three time points: baseline (~3 months pre-competition), pre-competition (upon arrival), and post-competition (day after the event). Data were collected using standardized instruments and analyzed in R. Descriptive statistics, Mann–Whitney U tests, Spearman’s correlations, Friedman tests, and individual delta values (Δ) were applied. Results: No significant between-group differences were observed in pre-competition cross-sectional analyses. Longitudinally, sleep duration was the only variable consistently differing between performance groups. Athletes who matched or improved performance showed greater sleep stability, whereas those who did not improve exhibited larger post-competition increases in sleep duration. Negative mood states decreased over time, and baseline vigor was higher in the higher-performing group. Sleep duration changes were negatively correlated with performance variation (ρ = −0.575, p = 0.003). Conclusions: Sleep duration was the variable most consistently associated with performance variation. Mood changes reflected reduced negative affect over time. Findings support longitudinal monitoring in Para powerlifting, although caution is warranted due to the observational design and small sample.

The complex pathways to elite sport are often affected by selection systems designed to identify talent, yet these very systems can inadvertently create systematic inequalities. A clear example of such a bias is the Relative Age Effect (RAE): the persistent advantage enjoyed by athletes born earlier in a selection year. The RAE raises urgent questions of fairness and efficacy in talent identification, particularly in youth sport contexts characterized by early selection and specialization (Cobley et al., 2009).Understanding the mechanisms, contextual moderators, and boundary conditions of the RAE is therefore central for designing talent pathways that prioritize long-term potential over transient advantage.Over the past four decades, research has consistently shown that RAE influences participation, identification processes, and long-term success across diverse sports and cultural contexts. As the sports community strives for more ethical and evidence-based practices, it becomes paramount to examine not only the prevalence of this phenomenon, but also the conditions under which it emerges, weakens, or disappears (Barnsley et al., 2025). This Special Issue advances this endeavor by offering new insights into developmental, contextual, and methodological dimensions that redefine how the RAE is conceptualized and evaluated.The seven original articles included here collectively extend the boundaries of RAE research. They span traditional and emerging contexts, from youth team sports to esports, and illustrate how relative age interacts with key factors such as maturation, sex, motor competence, athletic profiles, and performance metrics. Employing advanced analytical approaches, including artificial intelligence models alongside traditional comparative analyses, these studies deepen our understanding of the multifactorial nature of birthdate-related biases. Below, we summarize their main conceptual contributions. 2025) reveal substantial context dependence across competitive systems. In a comprehensive analysis of male and female athletes from Brazilian national teams over more than two decades, a significant presence of RAE was observed across all categories, although it was associated only with age category type and showed no relationship with collective performance or competition type (Pereira et al., 2025). Conversely, an investigation of players from the Israeli Premier League, including both domestic and foreign athletes, found no evidence of RAE, even when considering different cut-off dates and normative birth data. Although a larger number of athletes were born in the second quarter of the year, this difference was not statistically significant (Avugos & Malul, 2025). These contrasting results show that the RAE does not manifest uniformly across countries, competitive structures, or genders and highlight the importance of context-specific analyses in understanding its real impact on talent pathways.The contributions by Mikulič et al. (2025) andIrid et al. (2025) focus on talent identification in sports where the RAE is traditionally prevalent. Mikulič et al. (2025) analyzed isometric strength and speed performance in elite youth soccer players across different age groups, as well as potential differences in relative isometric strength between athletes selected and not selected for the national team. The authors concluded that relying solely on physical parameters for player selection and evaluation is insufficient in contemporary soccer. Complementing these findings, Irid et al. ( 2025) examined how athletic profiles and the RAE influence the future success of young basketball players, indicating that early advantages may interact with broader developmental factors.Together, both studies highlight the need to revise traditional talent identification models calling for multidimensional and longitudinal evaluation frameworks capable of capturing long-term potential while reducing systemic bias.In contrast to the prevalence of RAE observed in many traditional sports, Laxdal and Erikstad (2025) investigated whether similar patterns appear in the emerging field of professional esports. Analyzing data from more than 15,000 elite players across ten game titles, the authors found no practically meaningful differences in birth-month distribution.The cognitive and skill-based nature of esports, coupled with online competition structures and the absence of early age-based selection systems, appears to mitigate the structural mechanisms that typically generate relative age advantages in traditional sports.Collectively, the evidence in this Special Issue highlights the need to account for the interplay among individual, task, and environmental constraints (Wattie et al., 2015). This perspective supports a paradigm shift in talent development, moving from systems that privilege transient physical advantages to models that foster long-term potential and reduce structural bias. To advance in this direction, sport organizations must critically examine how the RAE manifests within their specific contexts and adapt their practices accordingly. The challenge for researchers, coaches and policymakers is to translate these insights into concrete actions by standardizing monitoring processes, broadening selection criteria, and piloting policy reforms. Through coordinated and sustained efforts, talent ecosystems may evolve toward greater fairness, efficacy, and enduring excellence.

Aim: The purpose was to analyze the Relative Age Effect (RAE) on players' representativeness in Top American soccer leagues, and analyze the RAE on players' market value in the above-mentioned leagues. Methods: The date of birth and perceived market value from 3494 male elite soccer athletes who participated in the 2022 season of the Argentinian (Superliga), Brazilian (Série A), Colombian (Liga Dimayor I), Mexican (Liga MX), and US American (MLS) soccer leagues were collected. The occurrence of the RAE among players was assessed in each of the leagues through a comparsion of the incidence of athletes born in each quarter and the frequency expected for each quarter. Results: The examinations of the players' birth quarters revealed a disparity in birth distribution across all leagues when compared to the expected values. Conclusion: Results also indicated that market values did not differ based on the players’ quarter of birth in Argentina, Brazil, Colombia, Mexico and USA.

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 < 0.001), second (p < 0.006), and third (p < 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 > 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 < 0.001), segundo (p < 0.006) y tercer (p < 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 > 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 < 0.001), segundo (p < 0.006) e terceiro (p < 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 > 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.

A proposta do estudo é verificar a existência do Efeito da Idade Relativa (EIR) em estudantes-atletas de voleibol que disputaram os Jogos Escolares de Mato Grosso em 2021, considerando a categoria e o sexo. A amostra foi composta por dados de 310 estudantes-atletas de voleibol, sendo 199 da categoria A (87 meninos; 112 meninas; 15 a 17 anos de idade) e 111 da categoria B (23 meninos; 88 meninas; 12 a 14 anos de idade), que participaram dos Jogos Escolares Mato-grossenses no ano de 2021. Os participantes foram divididos de acordo com a data de nascimento, considerando os trimestres do ano. Foram utilizados Testes de Qui-quadrado (χ2) para as comparações. Os resultados gerais não apresentaram diferença significativa ao comparar os quartis de nascimento dos atletas, no entanto, ao analisar por categorias, na categoria A, a distribuição dos atletas foi significativamente maior no Q1 em comparação com o Q4. Por outro lado, não foram encontradas diferenças nas distribuições dos quartis de nascimento na categoria B e em relação ao sexo. Observou-se a presença do EIR nos estudantes-atletas da categoria A sem relação com o sexo.

Vertical jump is an important skill that influences volleyball performance. In this study, we analyzed the relationship between vertical jump performance and birth quartile of Brazilian male youth volleyball players. We calculated chi-square goodness-of-fit tests to compare the athletes’ birthdate distributions in quarters of their birth years (Q1, Q2, Q3, and Q4) according to player age categories (U17, U18, U19, and U21). We calculated one-way ANOVAs to compare spike jump and block jump heights of players born in different quarters of the same year. Overall, we found a relative age effect (i.e., more players with birth dates early in the birth year) in U17 ( p < .001), U18 ( p < .001), U19 ( p < .001), and U21 ( p = .04). Regarding vertical jump performance, U18 athletes born in Q2 reached higher spike jump heights ( p = .006) and block jump heights ( p = .002) than athletes born in Q4, and U19 athletes born in Q1 reached higher block jump heights than athletes born in Q3 ( p = .049). There were no significant differences in vertical jump performance across birth quartiles among U17 and U21 athletes. Thus, a relative age effect was present in all age categories but not always reflected in vertical jump performance. Volleyball coaches and policymakers are still advised to employ strategies to ensure fairer opportunities for players born later in the year of their eligibility dates, as we found RAE to be sometimes, but not always, related to higher spike or block jump heights even among these older adolescents and young adult athletes.