RESUMO
BACKGROUND: Large-scale health surveys often consider sociodemographic characteristics and several health indicators influencing physical activity that often vary across subpopulations. Data in a survey for some small subpopulations are often not representative of the larger population. OBJECTIVE: We developed a multilevel regression and poststratification (MRP) model to estimate leisure-time physical activity across Brazilian state capitals and evaluated whether the MRP outperforms single-level regression estimates based on the Brazilian cross-sectional national survey VIGITEL (2018). METHODS: We used various approaches to compare the MRP and single-level model (complete-pooling) estimates, including cross-validation with various subsample proportions tested. RESULTS: MRP consistently had predictions closer to the estimation target than single-level regression estimations. The mean absolute errors were smaller for the MRP estimates than single-level regression estimates with smaller sample sizes. MRP presented substantially smaller uncertainty estimates compared to single-level regression estimates. Overall, the MRP was superior to single-level regression estimates, particularly with smaller sample sizes, yielding smaller errors and more accurate estimates. CONCLUSION: The MRP is a promising strategy to predict subpopulations' physical activity indicators from large surveys. The observations present in this study highlight the need for further research, which could, potentially, incorporate more information in the models to better interpret interactions and types of activities across target populations.
Assuntos
Exercício Físico , Estudos Transversais , Inquéritos Epidemiológicos , Humanos , Análise Multinível , Tamanho da AmostraRESUMO
Brazil has been the benchmark for volleyball performance for at least two decades, providing a unique context to examine expertise development. This study examined the variation in body size, functional capacities, motivation for achievement, competitiveness, and deliberate practice of youth volleyball players associated with differences in biological maturity status, chronological age, and accumulated deliberate volleyball practice, adopting a Bayesian multilevel modeling approach. We considered 68 female and 94 male adolescent players (14.2 years, 90% confidence interval: 12.7 to 16.0). Players were grouped by the onset of deliberate volleyball practice as related to biologic maturation milestones [pre-puberty deliberate practice onset (12% of the sample), mid-puberty deliberate practice onset (51% of the sample), and late-puberty deliberate practice onset (37% of the sample). There was substantial variation in body dimensions and functional performance by gender. There was no variation by gender for motivation for deliberate practice and motivation for achievement and competitiveness. The young volleyball players appeared to be highly motivated and committed to deliberate practice, achievement, and competitiveness. Alignment of chronological age, biological maturation, and accumulated training experience allow more in-depth insights into young volleyball players' development, providing sounder support for coaches´ decisions.
Assuntos
Desempenho Atlético/fisiologia , Motivação/fisiologia , Análise Multinível/métodos , Voleibol/estatística & dados numéricos , Logro , Adolescente , Teorema de Bayes , Tamanho Corporal/fisiologia , Brasil , Feminino , Humanos , Masculino , Desempenho Físico FuncionalRESUMO
In this study, we examined the probability of coaches' survival in the top Brazilian professional football championship considering variation across the competitive seasons between 2012 and 2017, considering a multilevel framework. We also considered whether previous coaching experience in the top Brazilian professional football championship would change the probability of coaches' survival across the season. The data considered 4,560 games from the top professional Brazilian football league (Campeonato Brasileiro Série A) between the 2012 and 2017 seasons. At the start of each season, the coach from each team was followed, being recorded at the time the event occurred, i.e., the coach being sacked. A total survival of 120 coaches was considered between the seasons of 2012 and 2017, i.e., 20 coaches at the beginning of each season. Coaches were assigned as novice (no previous experience as head coach in the top Brazilian championship) or experienced (with at least some previous experience as head coach in the top Brazilian championship). Data were available and extracted from the official website of the Brazilian Football Confederation. On average and considering un-pooled observations, the median life of a coach was about 16.5 rounds. Considering variation between 2012 and 2017 seasons, only about 26.3% (95% CI: 18.2-36.1) of the coaches ended a season without being sacked. By mid-season, at round 19, the probability of coaches' survival was 0.42 (95% CI: 0.32-0.53). Variation between season on survival estimates per round was substantial (between-season standard deviation = 0.48, 95% credible intervals: 0.25-0.95; corresponding to an inverse logit = 0.62, 95% CI: 0.56-0.72). There was no substantial variation between novice and experienced coaches' survival probability. The present results expose the vulnerability of the coaching context in Brazilian football, potentially highlighting an excessive emphasis on short-term results to mediate club management decisions.
RESUMO
Abstract The present study examined the changes in developmental assets among young basketball players during a 4-month competitive period, accounting for variation by age group. Additionally, we examined the age-related variation on developmental assets. Sixty-five adolescent basketball players aged between 9.5 to 17.3 years were considered. We used the Portuguese version of the Developmental Assets Profile Questionnaire. Multilevel modeling was used to estimate the magnitude of changes on developmental assets across the 4-month competitive season, as well as aligning assets scores by chronological age. Positive values and positive identity scores were substantially increased after the 4-month competitive sample. The other assets scores showed no variation across the competitive 4-month competitive season, independent of age group. There was a trend of linear decrease in developmental assets as the adolescent players got older. For positive values, there was a non-linear trend with a higher decrease rate between about 10 to 14 years, levelling off thereafter. Developmental assets did not appear to be influenced by exposure to a period of organized training and competition among adolescent basketball players. Hence, the observed decrease on developmental assets when aligning by age may reflect the influence of contextual and cultural environments of practice. This is of particularly interest for positive values, which refer to school engagement or and social justice, qualities that are not sport-specific but assume a key and importance position in sport participation for a positive role in youth development.
Resumo O presente estudo examinou as mudanças nos ativos de desenvolvimento entre jovens jogadores de basquetebol durante um período competitivo de 4 meses, considerando a variação por faixa etária. Adicionalmente, examinou-se a variação da idade no desenvolvimento dos Ativos. Participaram deste estudo 65 adolescentes jogadores de basquetebol com idade entre 9.5 a 17.3 anos. Utilizou-se a versão em português do Questionário de Perfil de Ativos de Desenvolvimento. O modelo multinível foi usado para estimar a magnitude das mudanças nos ativos de desenvolvimento, bem como alinhar as pontuações dos ativos por idade cronológica. Os valores de valores positivos e de identidade positiva foram aumentados após 4 meses competitivos. Já os outros não mostraram variação na mesma temporada, independente da faixa etária. Houve uma tendência de diminuição linear nos ativos de desenvolvimento à medida que os adolescentes se tornaram mais velhos. Para os valores positivos, houve uma tendência não linear com uma taxa de decréscimo mais alta entre cerca de 10 a 14 anos, nivelando-se depois disso. Os ativos de desenvolvimento não parecem ser influenciados pela exposição a um período de competição entre jogadores de basquete adolescentes. Assim, a diminuição nos ativos de desenvolvimento ao alinhar pela idade pode refletir a influência dos contextos culturais e de prática. Isto é particularmente interessante para valores positivos, que se referem ao envolvimento escolar ou à justiça social, qualidades que não são específicas do esporte, mas que assumem uma posição chave e importante na participação esportiva para desenvolvimento positivo da juventude.
RESUMO
Abstract Considering agility is a prerequisite for basketball performance and several agility tests have been used during the pre-draft assessment of the National Basketball Association (NBA), the aimed of this study was to examine the associations between pre-draft athletes´ performance scores in NBA draft combine testing protocol. The performance of 480 athletes invited to the NBA pre-draft assessment from 2010 to 2017 was considered. Tests in the NBA Draft Combine considered in this study included the Shuttle Run Test, Lane Agility Test, Sprint Test, and Jump Test (standing vertical leap). Zero order correlations were calculated to examine the associations between performance tests by fitting Bayesian linear regression models. Among running testing, both Shuttle Run Test [r=0.45, 95% confidence interval (CI) 0.34 to 0.56) and Sprint Test (r=0.45, 95% CI 0.37 to 0.54) were moderately associated with the Lane Agility Test. The association between the Sprint Test and Shuttle Run Test was moderate at best (r=0.27, 95% CI 0.16 to 0.38). Correlations between Jump Test and running tests were moderate to large, ranging from -0.51 to -0.19 (Lane Agility Test: r=-0.33, 95% CI -0.42 to -0.24; Shuttle Run Test: r=-0.19, 95% CI -0.31 to -0.07; Sprint Test: r=-0.51, 95% CI -0.59 to -0.43). As a conclusion, we found a moderate to large correlations between the tests performance of the NBA Draft Combine, implying that the overall procedures may provide in part overlapping information about basketball maximal short term performance.
Resumo O objetivo deste estudo foi examinar as associações entre os escores de desempenho dos atletas no Pre-Draft Combine da NBA. Foram examinados os desempenhos de 480 atletas nas avaliações do Pre-draft Combine da NBA de 2010 a 2017. Os testes do Draft Combine considerados incluíram o Shuttle Run Test, o Lane Agility Test, o Sprint Test e o Jump Test (salto vertical em pé). Correlações de ordem zero foram calculadas para examinar as associações entre os testes de desempenho através da adequação de modelos de regressão linear Bayesiana. Entre os testes de corrida, tanto o teste Shuttle Run (r = 0,45, intervalo de confiança (IC) de 95% 0,34 a 0,56) e teste de Sprint (r = 0,45, IC 95% 0,37 a 0,54) foram moderadamente associados com o Teste Lane Agility. A associação entre o Sprint Test e o Shuttle Run Test foi de moderada para alta (r = 0,27, IC 95% 0,16 a 0,38). As correlações entre o Teste de Salto e os testes de corrida foram de moderada a grande, variando de -0,51 a -0,19 (Lane Agility Test: r = -0,33, IC 95% -0,42 a -0,24; Teste Shuttle Run: r = -0,19, IC 95% -0,31 a -0,07; Teste de Sprint: r = -0,51, IC 95% -0,59 a -0,43). Assim, foi verificado uma correlação de moderada a grande entre o desempenho dos testes do Draft Combine da NBA, o que indica que os procedimentos gerais podem fornecer, parcialmente, informações sobrepostas sobre o desempenho máximo de curto prazo do basquetebol.