Testing Seefeldt's Proficiency Barrier: A Longitudinal Study.

The idea that proficiency in the fundamental movement skills (FMS) is necessary for the development of more complex motor skills (i.e., the proficiency barrier) and to promote health-enhancing physical activity and health-related physical fitness levels is widespread in the literature of motor development. Nonetheless, to the best of our knowledge, there is no study assessing whether children presenting proficiency below a specified proficiency barrier would demonstrate difficulty in improving performance in more complex skills-even when subjected to a period of practice in these complex skills. The present study tested this. Eighty-five normal children (44 boys) aged 7 to 10 years participated in the study. The intervention took place during 10 consecutive classes, once a week, lasting 40 min each. Six FMS (running, hopping, leaping, kicking, catching and stationary dribbling) and one transitional motor skill (TMS) (speed dribbling skill) were assessed. The results showed that only those who showed sufficient proficiency in running and stationary dribbling before the intervention were able to show high performance values in the TMS after intervention. In addition, in line with recent propositions, the results show that the basis for development of the TMS was specific critical components of the FMS and that the barrier can be captured through a logistic function. These results corroborate the proficiency barrier hypothesis and highlight that mastering the critical components of the FMS is a necessary condition for motor development.

Familial aggregation and heritability of markers of metabolic risk, physical activity, and physical fitness in nuclear families from Muzambinho (Minas Gerais, Brazil)

ABSTRACT Objective This study investigated the familial aggregation and heritability of markers of metabolic risk, physical activity, and physical fitness in nuclear families from Muzambinho (Minas Gerais, Brazil). Subjects and methods The study included members of 139 families, comprising 97 fathers (aged 40 ± 7 years), 129 mothers (35 ± 6 years), 136 sons (12 ± 4 years), and 121 daughters (12 ± 5 years). Evaluated markers included (A) body mass index, waist circumference, glycemia, and cholesterolemia, as metabolic risk markers; (B) total weekly volume of physical activity, as a physical activity marker; and (C) relative muscle strength, as a physical fitness marker. Correlations between family members and heritability (h2) were estimated using the software S.A.G.E. Results Significant familial correlations were obtained between parents-offspring for glycemia and cholesterolemia (both ρ = 0.21, p < 0.05) and relative muscle strength (ρ = 0.23, p < 0.05), and between siblings for waist circumference, glycemia, total weekly volume of physical activity, and relative muscle strength (ρ variation 0.25 to 0.36, p < 0.05). Heritability values were significant for almost all variables (h2 variations: 20% to 57% for metabolic risk markers, 22% for the total weekly volume of physical activity, and 50% for relative muscle strength), except for waist circumference (h2 = 15%, p = 0.059). Conclusion The presence of significant correlations between family members and/or significant heritability strengthens the possible genetic and/or common familial environment influence on metabolic risk markers, total weekly volume of physical activity, and relative muscle strength.

Familial aggregation and heritability of markers of metabolic risk, physical activity, and physical fitness in nuclear families from Muzambinho (Minas Gerais, Brazil).

OBJECTIVE: This study investigated the familial aggregation and heritability of markers of metabolic risk, physical activity, and physical fitness in nuclear families from Muzambinho (Minas Gerais, Brazil). SUBJECTS AND METHODS: The study included members of 139 families, comprising 97 fathers (aged 40 ± 7 years), 129 mothers (35 ± 6 years), 136 sons (12 ± 4 years), and 121 daughters (12 ± 5 years). Evaluated markers included (A) body mass index, waist circumference, glycemia, and cholesterolemia, as metabolic risk markers; (B) total weekly volume of physical activity, as a physical activity marker; and (C) relative muscle strength, as a physical fitness marker. Correlations between family members and heritability (h2) were estimated using the software S.A.G.E. RESULTS: Significant familial correlations were obtained between parents-offspring for glycemia and cholesterolemia (both ρ = 0.21, p < 0.05) and relative muscle strength (ρ = 0.23, p < 0.05), and between siblings for waist circumference, glycemia, total weekly volume of physical activity, and relative muscle strength (ρ variation 0.25 to 0.36, p < 0.05). Heritability values were significant for almost all variables (h2 variations: 20% to 57% for metabolic risk markers, 22% for the total weekly volume of physical activity, and 50% for relative muscle strength), except for waist circumference (h2 = 15%, p = 0.059). CONCLUSION: The presence of significant correlations between family members and/or significant heritability strengthens the possible genetic and/or common familial environment influence on metabolic risk markers, total weekly volume of physical activity, and relative muscle strength.

Birth weight, physical growth and body composition in children: A longitudinal study / Peso ao nascer, crescimento físico e composição corporal de crianças: um estudo longitudinal

ABSTRACT Objective To describe children's physical growth (body mass and height) velocity and body composition (fat percentage and Fat Free Mass); to investigate the magnitude of interindividual differences according to age, gender and birth weight categories, as well as to examine the differences in the average trajectories of children with Low Birth Weight and Normal Weight according to international references. Methods The sample consisted of 534 children (279 boys and 255 girls, 7 to 10 years old) evaluated in the first year of study and followed for 3 years with overlap between the ages of 7 and 9 years. Physical growth and body composition measurements included: height, body mass, fat percentage (%Fat) and Fat Free Mass. Multilevel Modelling was used. Results Birth weight was not associated with physical growth and body composition markers at 7 years old or with the velocity of their changes (p>0.05). There were significant interindividual differences in the trajectories of physical growth (height and body mass; p<0.001) and body composition (%Fat and Fat Free Mass; p<0.001). In plotting on international percentile charts, the trajectories of growth and body composition were within expected values for age and gender, regardless of birth weight. Conclusion There are significant differences in the dynamics of stature growth, body mass and Fat Free Mass, and Low Birth Weight has no influence on this trajectory. In addition, values are within the expected range for age and sex.

RESUMO Objetivo Este artigo teve por objetivo descrever a velocidade do crescimento físico (massa corporal e estatura) e a composição corporal (percentual de gordura e massa isenta de gordura) de crianças; investigar a magnitude das diferenças interindividuais em função da idade, gênero e categoria do peso ao nascer; e examinar a diferenciação das trajetórias médias das crianças com Baixo Peso ao Nascer e com Peso Adequado ao Nascer, relativamente às referências internacionais. Métodos A amostra foi composta por 534 crianças (279 meninos e 255 meninas, na faixa etária entre 7 e 10 anos de idade), avaliadas no primeiro ano de estudo e seguidas por três anos, com sobreposição de idade entre 7 e 9 anos. Foram medidas a estatura e a massa corporal, e estimados o percentual de gordura (%Gord) e a Massa Isenta de Gordura. As análises foram realizadas com a Modelagem Multinível. Resultados O peso ao nascer não apresentou associação com as variáveis de crescimento físico e composição corporal aos 7 anos de idade, bem como com seus incrementos dos 7 aos 10 anos (p>0,05). Há diferenças interindividuais significativas nas trajetórias de crescimento físico (estatura, massa corporal; p<0,001) e composição corporal (%Gord e Massa Isenta de Gordura; p<0,001). Na plotagem realizada em cartas percentílicas internacionais, independentemente do peso ao nascer, as trajetórias do crescimento e composição corporal encontram-se dentro dos valores esperados para idade e gênero. Conclusão O estudo concluiu que existem diferenças significativas no dinamismo do crescimento estatural, massa corporal e Massa Isenta de Gordura, e o Baixo Peso ao Nascer não exerce nenhuma influência nessa trajetória. Ademais, os seus valores estão dentro do expectável para idade e gênero.

Relação entre atividade física, aptidão física e risco cardiovascular: estudo em muzambinho, minas gerais / Relationship between physical activity, physical fitness and cardiovascular risk: study in muzambinho, minas gerais / Relación entre actividad física, aptitud física y riesgo cardiovascular: estudio en muzambinho, minas gerais

RESUMO Introdução: A relação negativa entre atividade física, aptidão física e risco cardiovascular está bem estabelecida em populações com baixos níveis de atividade física. Objetivo: O presente estudo investigou essa relação em adultos de Muzambinho, Minas Gerais, uma população com alta taxa de indivíduos fisicamente ativos. Métodos: Participaram 237 indivíduos (132 mulheres), na maioria jovens (44,3% entre 20 e 39 anos). Foram avaliados indicadores de risco cardiovascular (índice de massa corporal, circunferência da cintura, glicemia de jejum, colesterolemia de jejum e pressão arterial sistólica e diastólica), atividade física (volume semanal de atividade física total) e aptidão física (aptidão aeróbica e força manual relativa). Resultados: Mais de 90% dos indivíduos foram classificados como ativos (praticavam atividade física por mais de 150 min/semana). A regressão linear identificou associação negativa da força manual relativa e da aptidão aeróbica ao índice de massa corporal e a circunferência da cintura, bem como associação positiva da força manual relativa à pressão arterial diastólica. Os indicadores de atividade física e aptidão física não se associaram ao risco cardiovascular global. Conclusão: Nessa população, a relação inversa entre atividade física, aptidão física e risco cardiovascular limitou-se aos indicadores de aptidão física e aos de obesidade, sugerindo que em populações com alta taxa de indivíduos fisicamente ativos, o aumento da aptidão física, mas não da atividade física, pode ajudar a reduzir a obesidade. Nível de Evidência II; ECRC de menor qualidade.

ABSTRACT Introduction: The negative relationship between physical activity, physical fitness, and cardiovascular risk is well established in populations with low levels of physical activity. Objective: The present study investigated this relationship in adults from Muzambinho, Minas Gerais, a population with a high rate of physically active individuals. Methods: Two hundred and thirty-seven individuals (132 women), mostly young adults (44.3% between 20 and 39 years) were assessed. Cardiovascular risk predictors (body mass index, waist circumference, fasting blood glucose, fasting cholesterol, and systolic and diastolic blood pressure), physical activity (total weekly volume of total physical activity) and physical fitness (aerobic fitness and relative hand strength) were measured. Results: More than 90% of the individuals were classified as active (they practiced physical activity for more than 150 min/week). Linear regression identified a negative association of relative hand strength and aerobic fitness to body mass index and waist circumference, as well as a positive association of relative hand strength with diastolic blood pressure. The indicators of physical activity and physical fitness showed no association with global cardiovascular risk. Conclusion: In this population, the inverse relationship between physical activity, physical fitness and cardiovascular risk was limited to physical fitness and obesity indicators, suggesting that in populations with high rates of physically active individuals, the increase in physical fitness, but not in physical activity, can help reduce obesity. Level of Evidence II; Lesser quality RCT.

RESUMEN Introducción: La relación negativa entre actividad física, aptitud física y riesgo cardiovascular está bien establecida en poblaciones con bajos niveles de actividad física. Objetivo: Este estudio investigó esta relación en adultos de Muzambinho, Minas Gerais, una población con una alta tasa de individuos físicamente activos. Métodos: Participaron 237 individuos (132 mujeres), en su mayoría jóvenes (44,3% entre los 20 y 39 años). Se evaluaron indicadores de riesgo cardiovascular (índice de masa corporal, circunferencia de la cintura, glucosa en ayunas, colesterol en ayunas y presión arterial sistólica y diastólica), actividad física (volumen semanal de actividad física total) y aptitud física (capacidad aeróbica y fuerza relativa de la mano). Resultados: Más del 90% de los individuos fueron clasificados como activos (practicaban actividad física por más de 150 min/semana). La regresión lineal identificó asociación negativa de la fuerza relativa de la mano y la capacidad aeróbica al índice de masa corporal y la circunferencia de la cintura, así como la asociación positiva de la fuerza relativa de la mano a la presión arterial diastólica. Los indicadores de actividad física y aptitud física no se asociaron al riesgo cardiovascular global. Conclusión: En esta población, la relación inversa entre actividad física, aptitud física y riesgo cardiovascular se limitó a los indicadores de aptitud física y obesidad, lo que sugiere que en poblaciones con alta tasa de individuos físicamente activos, el aumento de la aptitud física, pero no de la actividad física, puede ayudar a reducir la obesidad. Nivel de Evidencia II; ECRC de menor calidad.

The Oporto mixed-longitudinal growth, health and performance study. Design, methods and baseline results.

BACKGROUND: Studies concerning child and adolescent growth, development, performance and health aimed at the multiple interactions amongst this complex set of variables are not common in the Portuguese speaking countries. AIM: The aim of this paper is to address the key ideas, methodology and design of the Oporto Growth, Health and Performance Study (OGHPS). SUBJECTS AND METHODS: The OGHPS is a multidisciplinary mixed-longitudinal study whose main purpose is to examine the multiple interactions among biological, environmental and lifestyle indicators that affect growth, development, health and performance of Portuguese adolescents aged 10-18 years old. RESULTS: This study briefly presents baseline results for growth, physical fitness and lifestyle behaviours for those participating in the cross-sectional sample (n ≈ 8000). Approximately 30% were over-fat or obese. On average, boys were more physically fit and active than girls. Few adolescents meet the guidelines for sleep duration (≈10%) and eating habits (16.2-24.8%), while 76-85% meet the recommended levels of moderate-to-vigorous physical activity. CONCLUSIONS: The OGHPS has an innovative approach due to its mixed-longitudinal design and the broad array of variables. Furthermore, subsequent analyses of the longitudinal data will enable a detailed exploration of important factors affecting the growth trajectories of health and performance variables and will also help to identify some of the most opportune times for interventions in terms of health behaviours.

The game variants in Europe. Trends and perspectives during youth competitive stages

AIMS: The aim of this study was to verify how European countries manage the type of game variants and their frequency during different age groups of youth competition. METHODS: Data were collected from the official rules of youth football championships. To identify countries homogenous groups according to their game variants, Two Step Cluster Analysis procedure was used while a nonparametric Kruskal-Wallis test was used to compare the game variants distribution in each Cluster. In order to correlate the game variants with age groups, a Chi-Square independence test and a Spearman ordinal correlation coefficient were used. The results showed there were five clusters with significant differences in their game variants distribution (X2 kw (4) = 22.149; p<0.001; n = 30) and a significant correlation between age group and game variant (χ2(63) = 477.724; p<0.001; n = 30). Specifically, the most used game variants in each age group were the five-a-side (F5) in Under-8; the nine-a-side (F9) in Under-12; the seven-a-side (F7) in Under-9 and Under10; and the eleven-a-side (F11) in and above Under-13. CONCLUSION: These results may contribute to understand the different country perspectives about the competitive game variants of youth football within the European space and its relation with diverse learning philosophies and pathways.(AU)

Developmental and physical-fitness associations with gross motor coordination problems in Peruvian children.

The aims of this cross-sectional study were to examine the developmental characteristics (biological maturation and body size) associated with gross motor coordination problems in 5193 Peruvian children (2787 girls) aged 6-14 years from different geographical locations, and to investigate how the probability that children suffer with gross motor coordination problems varies with physical fitness. Children with gross motor coordination problems were more likely to have lower flexibility and explosive strength levels, having adjusted for age, sex, maturation and study site. Older children were more likely to suffer from gross motor coordination problems, as were those with greater body mass index. However, more mature children were less likely to have gross motor coordination problems, although children who live at sea level or at high altitude were more likely to suffer from gross motor coordination problems than children living in the jungle. Our results provide evidence that children and adolescents with lower physical fitness are more likely to have gross motor coordination difficulties. The identification of youths with gross motor coordination problems and providing them with effective intervention programs is an important priority in order to overcome such developmental problems, and help to improve their general health status.

Physical activity, BMI and metabolic risk in Portuguese adolescents / Atividade física, IMC e risco metabólico em adolescentes portugueses

Abstract It has been reported, in the last decades, a significant decrease in physical activity (PA) levels, with a consequent increase in obesity and metabolic risk factors among youth. The aims of this study were to describe PA levels, the prevalence of overweight/ obesity and metabolic risk factors, and to examine the association between PA and body mass index (BMI) with metabolic risk among Portuguese youth. The sample comprises 212 Portuguese adolescents (12-16 years old). Height and weight were measured. PA was estimated with the Bouchard questionnaire (3 days recall), as well as with the use of a pedometer (used for 5 consecutive days). Metabolic risk factors comprised fasting glucose, triglycerides, HDL-cholesterol, systolic blood pressure and waist circumference. Subjects were classified as normal weight, overweight or obese according to BMI; the maturational status was indirectly estimated with the maturity offset procedure. A continuous metabolic risk score was computed (zMR) and PA values were divided into tertiles. Quisquare test, t-test and ANOVA were used in statistical analyses. SPSS 18.0 and WinPepi softwares were used and p<0.05. A moderate to high prevalence of overweight/obesity and HDL-cholesterol was found, as well as a high prevalence of high blood pressure and low to moderate PA levels among Portuguese youth. The relationship between BMI and zMR showed that obese adolescents have higher zMR when compared to normal weight or overweight adolescents. This finding suggests that increased levels of PA and reduction in the prevalence of overweight/obesity may have a positive role against the development of metabolic risk factors.

Resumo Tem-se verificado, nas últimas décadas, uma redução substancial nos níveis de atividade física (AF), com o consequente aumento da prevalência de sobrepeso/obesidade e fatores de risco metabólico entre jovens. O presente estudo teve por objetivos identificar os níveis de AF e as prevalências de sobrepeso/obesidade e risco metabólico, e associar o índice ponderal com os níveis de AF e risco metabólico em jovens portugueses. A amostra foi composta por 212 jovens portugueses (12-16 anos). Estatura e peso foram mensurados. AF foi estimada a partir do recordatório de 3 dias de Bouchard e pelo uso do pedômetro (durante 5 dias). Os indicadores de risco metabólico considerados foram: glicose, triglicerídeos, HDL-colesterol, tensão arterial sistólica e perímetro da cintura. Os sujeitos foram classificados consoante índice ponderal a partir do índice de massa corporal, enquanto que o estatuto maturacional foi estimado a partir do offset maturacional. Score contínuo de risco metabólico (zRM) foi calculado, e a AF foi dividida em tercis. Os testes estatísticos utilizados foram o Qui-quadrado, teste t independente e ANOVA, as análises foram conduzidas no SPSS 18.0 e WinPepi (p<0,05). Observou-se uma prevalência moderada a elevada de sobrepeso/obesidade e HDL-colesterol, uma elevada prevalência de risco para tensão arterial, e níveis de AF baixos a moderados entre jovens portugueses. A relação entre índice ponderal e zRM mostrou que adolescentes obesos apresentam maior zRM comparativamente aos adolescentes normoponderais ou com sobrepeso. Incrementos nos níveis de AF e redução da prevalência de sobrepeso/obesidade podem ter um papel relevante na redução de fatores de risco metabólico.

Skeletal Maturation, Body Size, and Motor Coordination in Youth 11-14 Years.

PURPOSE: The objective of this study is to estimate the relative contribution of biological maturation to variance in the motor coordination (MC) among youth and to explore gender differences in the associations. METHODS: Skeletal maturation (Tanner-Whitehouse 3), stature, body mass, and MC (Körperkoordinationstest für Kinder) were assessed in 613 youths, 284 boys and 329 girls 11-14 yr of age. Standardized residuals of skeletal age on chronological age were used as the estimate of skeletal maturity status independent of chronological age. Hierarchical multiple regression analyses were used to analyse associations between skeletal maturity status and MC. RESULTS: Skeletal maturity status by itself, i.e., standardized residuals of skeletal age on chronological age (step 3) explained a maximum of 8.1% of the variance in MC in boys (ΔR3 in the range of 0.0%-8.1%) and 2.8% of the variance in girls (ΔR3 in the range of 0.0%-2.8%), after controlling for stature, body mass and interactions of the standardized residuals of skeletal age on chronological age with stature and body mass. Corresponding percentages for the interactions of the standardized residuals of skeletal age and stature and body mass, after adjusting for stature and body mass (step 2) were 8.7% in boys (ΔR2 in the range of 0.3%-8.7%) and 7.1% in girls (ΔR2 in the range of 0.1%-7.1%). Chow tests suggested structural changes in ß-coefficients in the four MC tests among boys and girls, 12-13 yr. CONCLUSION: The percentage of variance in the four MC tests explained by skeletal maturation was relatively small, but the relationships differed between boys and girls. By inference, other factors, e.g., neuromuscular maturation, specific instruction and practice, sport participation, and others may influence MC at these ages.

Relationship between physical activity, physical fitness and multiple metabolic risk in youths from Muzambinho's study.

Negative associations between physical activity (PA), physical fitness and multiple metabolic risk factors (MMRF) in youths from populations with low PA are reported. The persistence of this association in moderately-to highly active populations is not, however, well established. The aim of the present study was to investigate this association in a Brazilian city with high frequency of active youths. We assessed 122 subjects (9.9 ± 1.3 years) from Muzambinho city. Body mass index, waist circumference, glycaemia, cholesterolaemia, systolic and diastolic blood pressures were measured. Maximal handgrip strength and one-mile walk/run test were used. Leisure time PA was assessed by interview. Poisson regression was used in the analysis. The model explained 11% of the total variance. Only relative muscular strength and one-mile walk/run were statistically significant (p < .05). Those who needed more time to cover the one-mile walk/run test had an increased in metabolic risk of 11%, and those with greater strength reduced the risk by about 82%. In conclusion, children and youths from an active population who need less time to cover the one-mile walk/run test or who had greater muscular strength showed a reduced metabolic risk. These results suggest that even in children and youths with high leisure time PA, a greater aerobic fitness and strength might help to further reduce their MMRF.

Tracking and its applicability to Physical Education and Sport / A noção de tracking e sua aplicação à Educação Física e ao Esporte

Abstract Tracking refers to the idea of maintaining a relative position within a given group of individuals as they change in time. This paper presents several approaches to study and analyze tracking (i.e., stability and predictability) and its application in physical education and sport. We will use data from a mixed-longitudinal study conducted in the city of Porto, Portugal, comprising 486 girls that were divided into two age cohorts: 12-14 years and 14-16 years. Body mass index (BMI) was the chosen variable in all statistical analyses of tracking. Statistical techniques to describe tracking included: autocorrelations, Foulkes & Davis gamma and Goldstein constancy index. Regardless of statistical procedure used, tracking BMI was moderate to high in each cohort, which could be due to the short follow-up period. However, each tracking statistics showed different aspects of inter-individual differences in intra-individual changes of girls' BMI. The use of any of the suggested procedures to study aspects of stability and predictability (i.e., tracking) in longitudinal studies requires a careful scrutiny of main goals and hypotheses to be tested.

Resumo O termo Tracking refere-se à noção de manutenção de posição relativa de valores de um dado grupo de sujeitos em função do tempo. O presente artigo apresenta diversas técnicas de estudo e análise do tracking (i.e., estabilidade e previsibilidade). Os dados utilizados provêm de um estudo longitudinal-misto da Região do Grande Porto, Portugal, compreendendo 486 meninas, divididas em duas coortes que abrangem as faixas etárias dos 12 aos 14 e dos 14 aos 16 anos. A variável eleita para as análises foi o índice de massa corporal (IMC). Os procedimentos estatísticos utilizados para descrever o tracking foram: autocorrelações, gama de Foulkes & Davis e índice de constância de Goldstein. Independentemente da estatística utilizada e face à curta duração do estudo, o tracking do IMC foi moderado a elevado em cada coorte. Contudo, cada procedimento de análise mostrou aspetos distintos das diferenças interindividuais nas mudanças intraindividuais do IMC das meninas. O uso parcimonioso de qualquer um dos procedimentos sugeridos para estudar aspetos da estabilidade e previsibilidade (i.e., do tracking) em estudos longitudinais exige o estabelecimento muito criterioso dos objetivos e hipóteses a serem testados.

Modelação multinível e delineamento longitudinal-misto na pesquisa em Educação Física e Ciências do Esporte / Multilevel modeling and mixed longitudinal design in the research in Physical Education and Sport Medicine

O propósito deste estudo é apresentar o uso da modelação multinível (MMN) com informação oriunda de um estudo longitudinal-misto sobre o crescimento, desenvolvimento e saúde de adolescentes portugueses. A amostra foi composta por 5155 indivíduos divididos em quatro coortes que abrangem as faixas etárias dos 10 aos 12, 12 aos 14, 14 aos 16 e 16 aos 18 anos. As variáveis de estudo foram a força de preensão manual e o percentual de gordura total (%GTotal). A análise mostrou trajetórias curvilíneas do desempenho de força de preensão, com maiores incrementos anuais nos meninos. O %GTtotal apresentou associação positiva com o desempenho da força estática; constatou-se uma forte variabilidade interindividual. O recurso ao delineamento longitudinal-misto permitiu a recolha mais célere da informação; e a metodologia MMN mostrou-se suficientemente flexível e robusta para acomodar, num modelo único, aspectos da mudança individual e das diferenças interindividuais do desempenho da força estática condicionados à ação do tempo.

The main aim of this study was to introduce the use of multilevel modeling in the data from a mixed longitudinal study concerning growth, development and health of Portuguese adolescents. The sample comprises 5155 subjects from 4 age cohorts: 10 to 12, 12 to 14, 14 to 16 and 16 to 18 years. Variables chosen for analysis were handgrip strength and percentage of total body fat. Multilevel modeling analysis showed a quadratic trajectory of adolescents' handgrip strength performance, with higher annual increasing in boys. The percentage of total body fat was positively associated with the static strength and there were marked interindividual differences. The use of a mixed longitudinal design allowed a faster data collection process; in addition, multilevel modeling analysis was sufficiently flexible and robust to accommodate, in a single model, aspects of individual and interindividual changes in static strength development over the time.

Secular trends in physical fitness of Mozambican school-aged children and adolescents.

OBJECTIVE: This study presents information about secular trends in physical fitness (PF) levels among Mozambican youth. METHODS: The sample comprises 3,851 subjects (1,791 boys; 2,060 girls) aged 8-15 years who were evaluated at three time points (1992, 1999, 2012). PF tests included handgrip strength, 10 m × 5 m shuttle-run, sit-and-reach, and 1-mile run/walk. Biological maturity was assessed by sexual characteristics, and percentage body fat was predicted using triceps and subscapular skinfolds. ANCOVA (controlling for age, maturity status, and percentage body fat) was used to compare mean differences in PF tests among the three time points, by sex. RESULTS: Children in 1992 were more flexible than those from 2012; boys handgrip strength increased from 1992 to 2012, while girls decreased their handgrip strength; youth in 1992 were faster and more agile than their 2012 peers; and a decrease was observed in cardiorespiratory fitness between 1992 and 1999 and between 1992 and 2012 for both sexes. CONCLUSIONS: A negative secular trend among Mozambican children's PF was observed over the last two decades, suggesting that socio-political, educational, and economical changes occurring during this period had a relevant effect on their PF. This negative trend suggests that development of intervention programs/strategies to improve PF among youth is warranted.

Birthweight, body composition, and motor performance in 7- to 10-year-old children.

AIM: The aim of this study was to analyse the influence of birthweight on motor performance and body composition in children. Further, we investigated whether associations between birthweight and motor performance changed after adjustment for current height, body mass index (BMI), fat-free mass (FFM), and % body fat. METHOD: A total of 483 children (251 males and 232 females) aged 7 to 10 years (mean 8.78, SD 1.0y) born in Vitória Santo Antão (northeast Brazil) were sampled. Motor performance was operationalized using different physical fitness components and gross motor coordination. Physical fitness was measured by handgrip strength, muscle endurance, explosive power, flexibility, agility, running speed, and maximal oxygen consumption (VO2max). Gross motor coordination was evaluated by means of the Körper Koordination Test für Kinder (KTK). RESULTS: Positive correlations between birthweight and height, BMI, and FFM were found. Birthweight was positively correlated with handgrip strength and negatively correlated with 20-meter sprint time, even after controlling for age, height, BMI, FFM, and % body fat. Birthweight was negatively associated with relative VO2max (mL/kg/min); however, the association was no longer significant after inclusion of BMI or FFM in the model. INTERPRETATION: Birthweight significantly predicted height, BMI, FFM, and performance in strength and velocity tests, but did not influence gross motor coordination.

Multi-level modelling of physical activity in nuclear families.

BACKGROUND: Few studies focus on the different dyadic relations among family members to study physical activity (PA) levels. AIM: The aim was to investigate predictors and sources of variance of PA levels in nuclear families using multi-level modelling. SUBJECTS AND METHODS: The sample consisted of 2661 Portuguese four-member nuclear families (10 644 subjects). PA was measured using a questionnaire and socioeconomic status (SES) was assessed by parental occupation. Height and weight were measured in children, while parents self-reported their values. RESULTS: The results showed that intra-generational similarities were higher than inter-generational, with correlation values of 0.26 and 0.10, respectively. SES was unrelated to any family members' PA level. Being male (ß = 0.26, t = 21.77), being older (ß = -0.36, t = -4.73) and greater BMI for mothers (ß = 0.02, t = 2.55) had effects on individuals' PA. CONCLUSION: These results suggest a strong dyadic resemblance in PA, showed different effects of gender, age and BMI on individuals' PA and demonstrated that multi-level modelling is a useful strategy to study PA in families.

Estudos longitudinais sobre o crescimento somático e desempenho motor: delineamentos, desafios, necessidades / Longitudinal studies on somatic growth and motor performance: designs, challenges, and needs

O objetivo principal desta revisão é fornecer uma visão geral dos principais estudos longitudinais e longitudinais-mistos que se centraram sobre o crescimento somático, maturação biológica e, mais recentemente, também no desempenho físico. Somente foram considerados os estudos realizados na América do Norte, Europa e países de língua portuguesa. Em primeiro lugar, são apresentadas as principais considerações teóricas, características gerais, o delineamento do estudo e análise estatística multivariada dos dados. Na segunda parte, é edificado o panorama geral sobre os estudos emblemáticos de natureza longitudinal e longitudinal-mista. Finalmente, foram considerados alguns dos principais desafios que se colocam à pesquisa longitudinal.

The main objective of the present review of the literature was to provide an overview of the major longitudinal and mixed longitudinal studies focusing on somatic growth, biological maturation, and, more recently, physical performance. We selected studies conducted in the USA, Europe, and Portuguese speaking countries. First, the main theoretical considerations, general characteristics, study designs, statistical analyses, and methodological challenges of the data were presented. Next, we provided an overview of the most important longitudinal and mixed longitudinal studies. Finally, the major challenges of the ongoing studies were outlined.

Physical activity, fitness and the metabolic syndrome in rural youths from Mozambique.

BACKGROUND: Except for North America and Europe, few studies have reported the association among physical activity (PA), cardiorespiratory fitness (CRF) and metabolic syndrome (MetS) in youths, especially for rural African youth. AIM: The aims of this study were to determine the prevalence of PA levels, CRF, MetS and its indicators, and examine the association between these variables in a school-aged sample of youth from rural Mozambique. SUBJECTS AND METHODS: The sample included 209 children and adolescents aged 7-15 years old from Calanga, a rural community in Mozambique. PA was estimated with a culturally-specific questionnaire. CRF was determined by 1-mile run test. Indicators of the MetS included fasting glucose, triglycerides, total cholesterol, blood pressure and body mass index. A continuous metabolic risk score was computed. RESULTS: Results showed high levels of PA and CRF and a low prevalence of MetS ( < 2%) among children and adolescents from Calanga. However, there was a moderately high prevalence of elevated blood pressure (81.8%) and triglycerides (18.7%), respectively. There were no significant associations between PA, CRF and MetS. CONCLUSION: Youths from Calanga are physically active and possess high CRF and their lifestyle may be a protective effect against MetS.

Physical activity, physical fitness, gross motor coordination, and metabolic syndrome: focus of twin research in Portugal.

A very brief history of Portuguese twin research in sport and human movement sciences is presented. Recruitment procedures, zygosity determination, and phenotypes are given for twins and their parents from the mainland, and Azores and Madeira archipelagos. Preliminary findings are mostly related to physical activity, health-related physical fitness, gross motor coordination, neuromotor development, and metabolic syndrome traits.

Frequency and precision of feedback and the adaptive process of learning a dual motor task / Frequência e precisão de "feedback" e o processo adaptativo de aprendizagem de uma tarefa motora de dupla demanda / Frecuencia y necesidad de feedback en el proceso adaptativo de aprendizaje de una tarea motora dual

This work investigated the effects of frequency and precision of feedback on the learning of a dual-motor task. One hundred and twenty adults were randomly assigned to six groups of different knowledge of results (KR), frequency (100%, 66% or 33%) and precision (specific or general) levels. In the stabilization phase, participants performed the dual task (combination of linear positioning and manual force control) with the provision of KR. Ten non-KR adaptation trials were performed for the same task, but with the introduction of an electromagnetic opposite traction force. The analysis showed a significant main effect for frequency of KR. The participants who received KR in 66% of the stabilization trials showed superior adaptation performance than those who received 100% or 33%. This finding reinforces that there is an optimal level of information, neither too high nor too low, for motor learning to be effective.

O presente estudo investigou os efeitos da frequência e precisão de "feedback" na aprendizagem de uma tarefa motora de dupla demanda. Cento e vinte adultos foram aleatoriamente designados a seis grupos de diferentes níveis de frequência (100%, 66% ou 33%) e precisão (específico ou geral) de conhecimento de resultados (CR). Na fase de estabilização, a tarefa combinada de posicionamento linear e controle de força manual foi executada com CR. Dez tentativas de adaptação sem CR foram executadas na mesma tarefa, com a introdução de uma força eletromagnética contrária à direção do movimento. A análise indicou efeito significativo no fator "frequência de CR". Aqueles que receberam CR em 66% das tentativas de estabilização obtiveram desempenho de adaptação superior quando comparados àqueles que receberam 100% ou 33% de CR. Esse achado reforça a existência de um nível ótimo de informação, nem muito alto nem muito baixo, para que a aprendizagem seja otimizada.

El presente estudio investigó los efectos de la frecuencia y necesidad de feedback en el aprendizaje de una tarea motora de dupla demanda. 120 adultos fueron aleatoriamente designados a seis grupos de diferentes niveles de frecuencia (100%, 66% o 33%) y necesidad (específico o general) de conocimiento de resultados (CR). En la fase de estabilización, la tarea de posicionamiento lineal y control de fuerza manual fue ejecutada con CR. Diez tentativas de adaptación sin CR fueron ejecutadas durante la misma tarea, con la introducción de una fuerza electromagnética contraria a la dirección del movimiento. El análisis indicó efecto significativo en el factor "Frecuencia de CR": aquellos que recibieron CR en 66% de las tentativas de estabilización obtuvieron desempeño de adaptación superior cuando comparados a aquellos que recibieron 100% o 33% de CR. Ese resultado refuerza la existencia de un nivel óptimo de información, ni muy alto ni muy bajo, para que el aprendizaje sea optimizado.