Physical (in)activity, and its predictors, among Brazilian adolescents: a multilevel analysis.

BACKGROUND: Physical activity is a multifactorial trait, determined by both individual and environmental characteristics, it seems relevant to understand the determinants related to youth guidelines accomplishment. The present study aimed to verify the differences between the Brazilian federative units regarding to the prevalence of youth physical activity guidelines accomplishment and to investigate the determinants related to the inter-individual differences in this accomplishment. METHODS: Sample comes from the 2015 Brazilian National School Health Survey (PeNSE), comprising 99,570 adolescents (51,527 girls, 13-17y), enrolled in 3039 schools. Adolescents reported the time they spend in moderate-to-vigorous physical activity daily, and they were categorized as active or inactive, if the guidelines were achieved, or not, respectively, and multilevel statistical analyses were used, including both child and school-level variables. Multilevel Binomial model was computed in the SuperMix software. RESULTS: The majority of the adolescents did not comply with the physical activity guidelines daily, where Bahian children complied the least, while those from Amazonas, Tocantins, and Mato Grosso do Sul complied the most. Boys (OR: 2.305; 95%CI: 2.277-2.334), older adolescents (OR: 1.044; 95%CI: 1.036-1.051), and those who spent more time in active travelling to/from school (OR: 1.001; 95%CI: 1.001-1.001) complied more the physical activity guidelines. At the school level, adolescents from larger schools (OR: 0.957; 95%CI: 0.928-0.986) tended to comply less with the guidelines. CONCLUSION: Significant differences between Brazilian federative units in youth daily physical activity guidelines compliance were observed, highlighting the role of individual but also environmental constraints in the Brazilian adolescents' engagement in physical activity.

Adolescent's movement behaviors and built environment: a latent class analysis.

BACKGROUND: Latent class analysis (LCA) is an alternative and innovative approach to verify the relation of the various combinations of the constructed environment and movement behavior (levels of physical activity, sedentary behavior, and sleep) characteristics. This study aimed to identify latent classes based on the characteristics of the neighborhood environment perceived by adolescents and their association with gender, socioeconomic status (SS), body composition and movement behaviors. METHODS: This cross-sectional study includes 309 Brazilian adolescents (14 to 16 years old, 57% female). The characteristics of the neighborhood environment perceived were analyzed by the Neighborhood Walkability for Youth Scale. Accelerometers were used for a week to evaluate the movement behaviors. Questionnaires assessed the screen times, total sitting time (TST), and sociodemographic characteristics. LCA was used for modeling the "Perceived Enviroment" variable, having been conducted in the poLCA (Polychromous Variable Latent Class Analysis) package of the R statistical software. RESULTS: Three classes were recognized: class 1, "Best Perceived Environment" with 23.03% of adolescents; class 2, "Moderate Perceived Environment", 63.33%; and class 3, "Worst Perceived Environment", 13.67%. Light physical activity (LPA), TST, and SS were associated with class prevalence. The adolescents with medium and low SS were, respectively, 3.42 (95% CI 1.62-7.21) and 4.18 (95% CI 1.66-10.50) more likely to belong to class 2, and those with low SS were 5.21 (95% CI 1.35-20.13) more likely to belong to class 3. Class 1 adolescents were associated with a lower chance (OR: 0.09, 95% CI 0.02-0.55) of involvement in 'adequate LPA time' compared to class 3. Class 1 adolescents were associated with a lower chance (OR: 0.31, 95% CI 0.12-0.79) of involvement in 'adequate TST' compared to class 2. There was a difference between the LPA and TST classes; class 3 presented a longer time in LPA than class 1; class 1 had higher TST than the other classes. CONCLUSION: The findings highlight the influence of neighborhood classes on adolescents' LPA and TST.

Biological and behavioral correlates of body weight status among rural Northeast Brazilian schoolchildren.

OBJECTIVES: The increase in the prevalence of overweight/obesity in youth is a public health problem worldwide; however, few studies have investigated its prevalence and correlates in children from the Brazilian Northeast region rural zone. The purpose of this study was (1) to estimate the prevalence of children's weight status according to sex, age, and birth weight categories; and (2) to investigate the links between biological and behavioral factors and weight categories. METHODS: The sample comprises 501 children (248 girls), aged 7-10 years, classified as low weight, normal weight, overweight, and obese using body mass index cut-points. Predicted variables included birth weight, percentage of body fat (%BF), fat free mass (FFM), physical fitness, and gross motor coordination. RESULTS: Data showed differences among weight groups for the predictor variables. Results of the logistic regression revealed that sex, age, %BF, FFM, physical fitness, and motor coordination seem to be relevant predictors of children's weight status, while no significant effect was observed for birth weight. CONCLUSION: Children with lower physical fitness levels as well as those with lower motor coordination quotient are more likely to be overweight and/or obese. No significant relationship was observed between birth weight and weight status in childhood. Strategies to reduce childhood obesity should consider biological, behavioral, and also environmental predictors.

Identifying the best body-weight-status index associated with metabolic risk in youth.

This study investigated the association of six different anthropometric markers with metabolic syndrome to find the most suited to predict children at risk. Sample comprises 1324 Portuguese youth (701 girls, 623 boys), aged 10-17 years. Six anthropometric markers were included: body mass index (BMI), BMI z-score, tri-ponderal index (TPI), waist circumference (WC), WC/height ratio (WC/H), and WC/H adjusted ratio (WC/Hadj ). A standardized metabolic risk score (zMR) was computed by summing of standardized values for fasting glucose, triglycerides, high-density lipoprotein cholesterol, and mean arterial blood pressure. The associations between zMR and anthropometric markers were assessed using univariate and multivariate analyses. Receiver operating characteristic (ROC) curve analysis was used to identify the optimal values that best predict metabolic risk of each anthropometric marker. Among the studied predictors, BMI z-score, followed by BMI and WC, was most highly associated with zMR, while WC/Hadj was the weakest predictor. ROC analyses showed significant AUCs for all markers, yet the discrimination was poor (AUCs from 0.60 to 0.68), with sensitivity ranging from 45.5% to 67.5% and specificity from 72.6% to 81.9%. The optimal cut-off values to predict metabolic risk were 1.62, 23.1 kg/m2 , 71.0 cm, 18.0 kg/m3 , 0.47, and 0.50, for BMI z-score, BMI, WC, TPI, WC/H, and WC/Hadj , respectively. BMI z-score, followed by BMI and WC, were the most relevant anthropometric markers to predict metabolic risk in youth, while WC/Hadj was the worst predictor. Results suggest that anthropometric markers should continue to be used as clinical tools to identify youth at risk.

Active and strong: physical activity, muscular strength, and metabolic risk in children.

OBJECTIVES: This study explored the associations among physical activity, muscular strength, and metabolic risk among children. METHODS: The sample included 378 Portuguese children (213 girls; 9-11 years). Moderate-to-vigorous physical activity was assessed by accelerometry and children were classified as active (≥60 min/day) or insufficiently active (<60 min/day). Static strength was expressed as the ratio of handgrip strength/body weight and used to classify children as having high (≥P50) or low (

Deficits in anthropometric indices of nutritional status and motor performance among low birth weight children from Maputo City, Mozambique.

OBJECTIVE: To evaluate associations between low birth weight (LBW) and anthropometry, body composition, physical fitness, and gross motor coordination among schoolchildren from Maputo, Mozambique. METHODS: A total of 353 children aged 7 to 10 years old from both genders born in Maputo (Mozambique) were sampled. The sample was divided into two groups: LBW (n = 155) and normal birth weight (NBW, n = 198). Body composition measurements and indices weight-for-age, height-for-age, and weight-for-height were assessed. Physical fitness was assessed by handgrip strength, flexibility, agility, long jump, and running speed. Gross motor coordination was evaluated by using the Korper Koordination Test fur Kinder (KTK) battery. RESULTS: LBW children were lighter and smaller than NBW children with reduced indices for weight-for-age and height-for-age. They also showed a reduced performance in handgrip strength and sideways movement tests. These differences remained significant even after adjustment for age, gender, body size, and fatness skinfold thickness. CONCLUSION: LBW seems to be the major factor that influences anthropometry, and is a predictor of low muscle strength and low performance on sideways movement tests. This result suggests that growth faltering in LBW children is associated with adverse health consequences, even after controlling for gender, age, fatness, and body size.

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.

Differences in motor performance between children and adolescents in Mozambique and Portugal: impact of allometric scaling.

BACKGROUND: Children from developed and developing countries have different anthropometric characteristics which may affect their motor performance (MP). AIM: To use the allometric approach to model the relationship between body size and MP in youth from two countries differing in socio-economic status-Portugal and Mozambique. SUBJECTS AND METHODS: A total of 2946 subjects, 1280 Mozambicans (688 girls) and 1666 Portuguese (826 girls), aged 10-15 years were sampled. Height and weight were measured and the reciprocal ponderal index (RPI) was computed. MP included handgrip strength, 1-mile run/walk, curl-ups and standing long jump tests. A multiplicative allometric model was adopted to adjust for body size differences across countries. RESULTS: Differences in MP between Mozambican and Portuguese children exist, invariably favouring the latter. The allometric models used to adjust MP for differences in body size identified the optimal body shape to be either the RPI or even more linear, i.e. approximately (height/mass(0.25)). Having adjusted the MP variables for differences in body size, the differences between Mozambican and Portuguese children were invariably reduced and, in the case of grip strength, reversed. CONCLUSION: These results reinforce the notion that significant differences exist in MP across countries, even after adjusting for differences in body size.

Sex-specific genetic effects in physical activity: results from a quantitative genetic analysis.

BACKGROUND: The objective of this study is to present a model to estimate sex-specific genetic effects on physical activity (PA) levels and sedentary behaviour (SB) using three generation families. METHODS: The sample consisted of 100 families covering three generations from Portugal. PA and SB were assessed via the International Physical Activity Questionnaire short form (IPAQ-SF). Sex-specific effects were assessed by genotype-by-sex interaction (GSI) models and sex-specific heritabilities. GSI effects and heterogeneity were tested in the residual environmental variance. SPSS 17 and SOLAR v. 4.1 were used in all computations. RESULTS: The genetic component for PA and SB domains varied from low to moderate (11% to 46%), when analyzing both genders combined. We found GSI effects for vigorous PA (p = 0.02) and time spent watching television (WT) (p < 0.001) that showed significantly higher additive genetic variance estimates in males. The heterogeneity in the residual environmental variance was significant for moderate PA (p = 0.02), vigorous PA (p = 0.006) and total PA (p = 0.001). Sex-specific heritability estimates were significantly higher in males only for WT, with a male-to-female difference in heritability of 42.5 (95% confidence interval: 6.4, 70.4). CONCLUSIONS: Low to moderate genetic effects on PA and SB traits were found. Results from the GSI model show that there are sex-specific effects in two phenotypes, VPA and WT with a stronger genetic influence in males.

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.

Correlates of sedentary time in children: a multilevel modelling approach.

BACKGROUND: Sedentary behaviour (SB) has been implicated as a potential risk factor for chronic disease. Since children spend most of their awake time in schools, this study aimed to identify individual- and school-level correlates of sedentary time using a multilevel approach, and to determine if these correlates have a similar effect in normal weight (NW) and overweight/obese (O/O) children. METHODS: Sample comprised 686 Portuguese children aged 9-10 years from 23 schools that took part in the ISCOLE project. Actigraph GT3X + accelerometers were used 24 hours/day for 7 days to assess sedentary time (daily minutes <100 counts/min); BMI was computed and WHO cut-points were used to classify subjects as NW or O/O. Sex, BMI, number of siblings, family income, computer use on school days, and sleep time on school days were used as individual-level correlates. At the school level, school size (number of students), percentage of students involved in sports or physical activity (PA) clubs, school promotion of active transportation, and students' access to equipment outside school hours were used. All multilevel modelling analysis was done in SPSS, WINPEPI, and HLM. RESULTS: School-level correlates explain ≈ 6.0% of the total variance in sedentary time. Results (ß ± SE) showed that boys (-30.85 ± 5.23), children with more siblings (-8.56 ± 2.71) and those who sleep more (-17.78 ± 3.06) were less sedentary, while children with higher family income were more sedentary (4.32 ± 1.68). At the school level, no variable was significantly correlated with sedentary time. Among weight groups, variables related to sedentary time in NW were sex, sleep time and family income, while in O/O sex, number of siblings and sleep time were significant correlates. No school-level predictors were significantly associated in either of the weight groups. CONCLUSION: Notwithstanding the relevance of the school environment in the reduction of children's sedentary time, individual and family characteristics played a more relevant role than the school context in this study.

Clustering of body composition, blood pressure and physical activity in Portuguese families.

AIM: The purposes of this study were: (i) to identify familial resemblances in body fat, blood pressure (BP) and total physical activity (TPA); (ii) to estimate the magnitude of their genetic and environmental influences; and (iii) to investigate shared familial aggregation among these phenotypes. SUBJECTS AND METHODS: The sample comprised 260 nuclear families from Portugal. Body fat was assessed by bioelectrical impedance. BP was measured by an oscillometric device. TPA was estimated by the Baecke questionnaire. Familial correlation analyses were performed using Generalized Estimating Equations. Quantitative genetic modelling was used to estimate maximal heritability, genetic and environmental correlations. RESULTS: Familial intra-trait correlations ranged from 0.15-0.38. Genetic and common environmental factors explained from 30%--44% of fat mass depots and BP and 24% of TPA. Genetic correlations were significant between BP and the fat mass traits (p < 0.05). Environmental correlations were statistically significant between diastolic BP and total body fat, trunk fat and arm fat (p < 0.05) and TPA and other phenotypes. CONCLUSIONS: The results suggest familial resemblance in the variation of body fat, BP and TPA, showing partial pleiotropic effects in the variation in body fat phenotypes and BP. TPA only shares common environmental influences with BP and body fat traits.

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.

Nutritional status and its association with physical fitness, physical activity and parasitological indicators in youths from rural Mozambique.

BACKGROUND: Little information exists about the relationship of nutritional status and motor performance conditional on asymptomatic parasitemia in rural African children. AIMS: The aims of this study were to (1) determine if malnourished youths from rural African areas have lower levels of physical fitness (PF) and physical activity (PA) compared to normal weight youths, (2) verify the biological relevance of anthropometric criteria used to classify nutritional status in youth, and (3) determine the prevalence of parasitological indicators, and its association with nutritional status and PF. METHODS: The sample comprised 794 youths (6-17 years) from Calanga, a rural community in Mozambique. PF tests were selected from standardized test batteries, and PA was estimated by accelerometry. Nutritional status was defined according to WHO recommendations for stunting, wasting and normal weight. Parasitological indicators were determined based on stool specimens' analysis. RESULTS: In general terms the normal group out-performed the other nutritional groups (stunted and wasted) for PF. However, no significant differences were found for PA among nutritional groups. There were also no significant differences in prevalence of intestinal parasites. CONCLUSIONS: Nutritional status was not associated with PA levels or the prevalence of parasitological indicators in youth, but was related to physical performance.

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.

How Do Health, Biological, Behavioral, and Cognitive Variables Interact over Time in Children of Both Sexes? A Complex Systems Approach.

The present study examined gender differences in health, physical activity, physical fitness, real and perceived motor competence, and executive function indicators in three time points, and analyzed the dynamic and non-linear association between health, biological, behavioral, and cognitive variables in children followed over time. A total of 67 children (aged between six and 10 years) were followed during two years and split into two cohorts (six to eight years old: C1; eight to 10 years old: C2). Data regarding health, physical activity, real and perceived motor competence, physical fitness, and executive function indicators were obtained according to their respective protocols. Comparison tests and network analysis were estimated. Significant gender differences were found in both cohorts. The emerged networks indicated different topologies in both cohorts. No clusters were observed between the variables in C1, and there was a greater number of interactions at eight years of age. Sparse networks were observed in children aged eight and 10 years in C2, and greater connectivity was observed at nine years of age between health, physical fitness, motor competence, and physical activity indicators. This study showed that there are non-linear dynamic relationships between health, biological, behavioral, and cognitive variables over time during child development.

Ecological correlates related to adolescent movement behaviors: A latent class analysis.

The ecological model has been widely used to help researchers understand the multiple influences in the physical activity (PA) and in the sedentary behaviors in isolated forms. To date, few correlates concerning the behavioral groupings of PA and sedentary behaviors have been studied. In this context, this study aimed to identify movement behaviors' latent classes related to the different adolescents' PA and sedentary time expressions, as well as their associations with individual, sociodemographic, family, and environmental correlates. This is a cross-sectional study with 309 students aged between 14 and 16. Latent Class Analysis was used to identify movement behavior classes based on light PA, moderate to vigorous PA, number of steps, sedentary time, and screen time (ST). An accelerometer was used to evaluate movement behaviors. The individual, sociodemographic, family, and environmental correlates were assessed by questionnaires. Three classes were identified: Class 1, "Active and Non-Sedentary" (8.10% of the sample), Class 2, "Active and Sedentary" (28.5%), and Class 3, "Inactive and Sedentary" (63.4%). Those with low fruit intake, low aerobic fitness, stressed and whose head of the family obtained an 'elementary school' level education were, respectively, 7.17, 3.59, 3.56, and 4.40 times more likely to belong to class 3 than class 1. Those with medium and high socioeconomic status were 82% and 83% less likely to belong to class 1 than classes 2 and 3, respectively. Adolescents who perceived the neighborhoods with the best access to diversified land use, street connectivity, walking/pedaling ease, and traffic safety attributes, were 84%, 85%, 82%, and 82%, respectively less likely to belong to class 1 than class 2. It is concluded that distinct correlates can be associated with the movement behaviors classes.

Relação entre indicadores de risco à saúde e componentes do somatótipo consoante atividade física em crianças / Relación entre indicadores de riesgo para la salud y componentes del somatótipo según la actividad física en niños / Relationship between health risk indicators and somatotype components according to physical activity in children

Este estudo analisou a relação entre indicadores de risco à saúde e as componentes do somatótipo consoante os níveis de atividade física em crianças. Trata-se de uma pesquisa epidemiológica de base escolar, composta por 168 crianças (6 a 11 anos) de ambos os sexos. Informações demográficas foram obtidas. Avaliações antropométricas (estatura; massa corporal; pregas de adiposidade subcutânea; perímetros do braço contraído, cintura, quadril e panturrilha), pressão arterial sistólica e diastólica, e atividade física (ativo; inativo) foram mensuradas. O somatótipo, razão cintura-quadril e razão cintura-estatura foram calculados. Análise de comparação, correlação e regressão linear múltipla foram realizadas, considerando intervalo de confiança de 95%. Meninos apresentaram maior número de passos, razão cintura-quadril e cintura-estatura. Crianças ativas eram mais velhas, possuíam maior perímetro de cintura, quadril e pressão arterial sistólica. No grupo fisicamente ativo, o sexo esteve associado diretamente ao perímetro de cintura e razão cintura-estatura, enquanto a idade associou-se com a perímetro de quadril e pressão arterial diastólica. Nas crianças inativas, todas as variáveis preditoras (exceto para a variável sexo em relação ao perímetro de quadril) mostraram-se significativas para o perímetro da cintura e quadril, explicando, conjuntamente, ~83% e 85% da expressão destas variáveis, respectivamente. A relação entre indicadores de risco à saúde e as componentes do somatótipo foi maior em crianças inativas. Independentemente do nível de atividade física, a endomorfia mostrou relação significativa com os componentes de saúde, com maior efeito no grupo inativo, tendo em vista a associação com a composição corporal dos sujeitos.

Este estudio analizó la relación entre indicadores de riesgo para la salud y los componentes del somatótipo según los niveles de actividad física en niños. Se trata de una investigación epidemiológica, compuesta por 168 niños (6 a 11 años) de ambos sexos. Fueron mensuradas: evaluaciones antropométricas (estatura; masa corporal; pliegues de adiposidad subcutánea; perímetros del brazo contraído, cintura, cuadril y pantorrilla), presión arterial sistólica y diastólica, y actividad física (activo/inactivo); el somatótipo, a través del cálculo de: razón cintura-cuadril y razón cintura-estatura. Se realizó el análisis de comparación, correlación y regresión lineal múltiple, considerando intervalo de confianza del 95%. Los niños presentaron mayor número de pasos, razón cintura-cuadril y cintura-estatura. Los niños activos eran mayores, tenían mayor perímetro de cintura, cuadril y presión arterial sistólica. En el grupo físicamente activo, el sexo estuvo asociado directamente al perímetro de cintura y razón cintura-estatura, mientras que la edad se asoció con el perímetro de cuadril y presión arterial diastólica. En los niños inactivos, todas las variables predictoras (excepto para la variable sexo con relación al perímetro de cuadril) se mostraron significativas para el perímetro de la cintura y cuadril, explicando, conjuntamente, ~83% y 85% de la expresión de estas variables, respectivamente. La relación entre indicadores de riesgo para la salud y los componentes del somatotipo fue mayor en niños inactivos. Independientemente del nivel de actividad física, la endomorfia mostró una relación significativa con los componentes de salud, con mayor efecto en el grupo inactivo, con vistas a la asociación con la composición corporal de los sujetos.

This study analysed the relationship between health risk indicators and somatotype components according to physical activity levels in children. This epidemiological and school-based research comprised 168 children of both sexes (56% boys), aged between 6 to 11 years. Demographic information (sex, age) was obtained. Anthropometric information (body height; body mass; contracted arm, waist, hip, and calf circumferences), body composition (subcutaneous adiposity and somatotype), systolic and diastolic blood pressure, and physical activity level (active; inactive) were measured. The waist-hip ratio and waist-to-height ratio were computed. Comparison, correlation, and multiple linear regression analysis were performed, considering 95% of the confidence interval. Boys presented higher values for physical activity, waist-hip, and waist-to-height ratio. Active children were older, had a larger waist and hip circumference, and higher systolic blood pressure. Among the active group, sex was associated with waist circumference and waist-to-height ratio, while age was associated with hip circumference and diastolic blood pressure. Among inactive children, all predictors (except for sex for hip circumference) were significantly associated with waist and hip circumferences, explaining ≅83% and 85% of the expression of these variables, respectively. The relationship between health risk indicators and somatotype components was higher among inactive children. Regardless of the physical activity level, the endomorphic component shows a significant relationship with health components, with a higher effect among the inactive group, considering the body composition association.

A multilevel analysis of health-related physical fitness. The Portuguese sibling study on growth, fitness, lifestyle and health.

This study investigates biological, behavioural and sociodemographic correlates of intra-pair similarities, and estimates sibling resemblance in health-related physical fitness (PF). The sample comprises 1101 biological siblings (525 females) aged 9-20 years. PF components and markers were: morphological [waist circumference (WC) and %body fat (%BF)], muscular [handgrip strength (GS) and standing long jump (SLJ)], motor [50-yard dash (50YD) and shuttle run (SR)], and cardiorespiratory (1-mile run). Biological maturation was assessed; physical activity (PA), TV viewing and socioeconomic status (SES) information was obtained. On average, older and more mature subjects are better performers in all PF components; PA was negatively associated with SR, while SES was negatively associated with SLJ and SR. A pattern was observed in the intraclass correlations (ρ) wherein same sex siblings demonstrate greater resemblance for most PF components (sister-sister: 0.35≤ ρ≤0.55; brother-brother: (0.25≤ρ≤0.60) than brother-sister pairs (BS) (0≤ρ≤0.15), except for %BF (ρBB>ρSS>ρBS), and the 1-mile run (ρSS>ρBS>ρBB). In conclusion, behavioural and sociodemographic correlates play different roles in siblings PF expression. Further, a significant familial PF resemblance was observed with different trends in different sibling types, probably due to variations in shared genetic factors and sociodemographic conditions.

Relationship between Sedentariness and Moderate-to-Vigorous Physical Activity in Youth: A Multivariate Multilevel Study.

This study aimed to jointly analyse moderate-to-vigorous physical activity (MVPA) and sedentariness, and their correlates, in children within their school contexts, using a multivariate multilevel approach. The sample comprises 499 Portuguese children (284 girls) from 23 schools. MVPA and sedentary time were estimated by accelerometer. A set of predictor variables from both child and school levels was tested. Overall, schools explained a small amount of the total variance in both MVPA (5.6%) and sedentariness (3.2%), and a correlation coefficient of -0.45 (p < 0.05) was found between MVPA and sedentariness at the child level. Number of siblings and socioeconomic status (SES) were significantly associated with both sedentariness (SES: ß = 2.372 ± 1.183; siblings: ß = -8.127 ± 2.759) and MPVA (SES: ß = -1.535 ± 0.421; siblings: ß = 2.822 ± 0.977), but with opposite signs. Body Mass Index (BMI) (ß = -4.804 ± 1.898) and sex (male) (ß = 21.561 ± 3.496) were only associated with MVPA. None of the school correlates were statistically significant in their joint effects to simultaneously explain sedentariness and MVPA. These results suggest that although MVPA and sedentariness may be different constructs, they are correlated and this should be taken into account when designing strategies to reduce children's sedentariness and increase their MVPA. In addition, the small effect of the school context on this relationship highlights the important roles of child and family characteristics.