Transitional Movement Skill Dependence on Fundamental Movement Skills: Testing Seefeldt's Proficiency Barrier.

Purpose: In 1979 Vern Seefeldt postulated that individuals that did not achieve a given level of proficiency in the fundamental movement skills (FMS) would be limited in performance on new and more complex skills during development. This hypothesis, the proficiency barrier, inspired research in motor development but, to the best of our knowledge, was never empirically tested. The present article tested three potential mathematical functions (linear, sigmoidal and piecewise) describing the proficiency barrier relating FMS with a transitional movement skill (TMS, a more complex movement skill). Methods: 87 children aged 7 to 10 years were tested on six skills of the TGMD-2 test battery (running, hopping, leaping, kicking, catching and stationary bouncing) and dribbling (a combination of running and stationary bouncing). Results: The results showed evidence for the proficiency barrier based on a specific sigmoidal relation. We also identified critical movement aspects from FMS that seem to induce this relation. Conclusion: There is some evidence supporting Seefeldt's Proficiency Barrier.

The influence of anthropometric variables, body composition, propulsive force and maturation on 50m freestyle swimming performance in junior swimmers: An allometric approach.

The purpose of the current article was to use allometric models to identify the best body size descriptors and other anthropometric variables, body composition, and offset maturity that might be associated with the youngsters' 50m personal-best (PB) swim speeds (m·s-1). Eighty-five competitive swimmers (male, n=50; 13.5±1.8 y; female, n=35; 12.6±1.8 y) participated in this study. Height, body mass, sitting height, arm span, skinfolds, arm muscle area (AMA), and maturity offset were assessed. Swimming performance was taken as the PB time recorded in competition, and the propulsive force of their arm (PFA) was assessed by the tied swimming test. The multiplicative allometric model relating 50m PB swim speeds (m·s-1) to all the predictor variables found percentage body fat as a negative [(BF%) ß= -.121±.036; P=0.001], and PFA (PFA ß=.108±.033; P=0.001) and the girl's arm span (ß=.850±.301; P=0.006), all log-transformed, as positive significant predictors of log-transformed swim speed. The adjusted coefficient of determination, Radj2 was 54.8% with the log-transformed error ratio being 0.094 or 9.8%, having taken antilogs. The study revealed, using an allometric approach, that body fatness and PFA were significant contributors to 50m freestyle swim performance in young swimmers.

Muscular Strength Spurts in Adolescent Male Basketball Players: The INEX Study.

Although successful performance in basketball requires high levels of muscular strength during adolescence, its development is confounded by the effects of normal growth. We examine the timing, intensity and sequence of muscular strength according to biological age (years from peak height velocity (PHV)) and hypothesize that young basketball players attain their peak muscular strength spurts around PHV. A total of 160 adolescent male basketballers, aged 11-15 years, were followed bi-annually over 3 consecutive years. The years from attainment of PHV and peak weight velocity (PWV) were estimated and five muscular strength measures (sit-ups, handgrip, seated medicine ball throw, squat jump and countermovement jump) were aligned to years from PHV in 3-month intervals. Strength velocities were estimated using a non-smooth mathematical model. The mean ages at-PHV and at-PWV were 13.90 ± 1.40 years and 13.90 ± 1.79 years, respectively. Maximal velocity in sit-ups was attained 6 months prior to attainment of PHV (intensity = 10.69 repetitions·year-1), whereas maximal velocity in squat jump occurred 6 months after-PHV (intensity = 3.93 cm·year-1). Handgrip strength, seated medicine ball throw and countermovement jump maximal velocity peaked at-PHV (intensity = 8.47 kgf·year-1, intensity = 0.75 m·year-1, intensity = 5.59 cm·year-1, respectively). In general, maximal velocity spurts did not differ in their timing, with the velocities reaching a peak concurrent with PHV and PWV or within 6 months of its attainment. Basketball coaches, as well as strength and conditioning trainers, should consider individual differences in strength development and be aware of rapid periods of growth in stature when planning and designing muscular strength training regimes.

Association between body mass index and individual characteristics and the school context: a multilevel study with Portuguese children / Relação entre o índice de massa corporal e as características individuais e do contexto escolar: um estudo multinível com crianças portuguesas

Abstract Objective The aim of this study was to examine the association between individual and school context characteristics with the body mass index of Portuguese children. Methods The sample comprised 1641 children (847 boys) aged 6-10 years from the North and Central regions of Portugal. Regarding the individual characteristics, age, gender, city of residence, levels of physical activity, and physical fitness were assessed. Concerning the school context characteristics, the surrounding environment, school size, presence of recreational characteristics and space, and presence of a sports court and of physical education classes were considered. Children's body mass index was the dependent variable. The multilevel analysis was carried out in HLM 7.0 software. Results The predictors of the child and the school context explained, respectively, 97.3% and 2.7% of the total body mass index variance. Regarding the individual characteristics, older children, boys, and those who had lower performance at the 1-mile run/walk, curl-up, push-up, and higher performance in trunk lift tests showed higher BMI. Further, urban schools with higher recreational spaces were positively associated with children's body mass index. Conclusion School context variables have a reduced effect on body mass index variation compared to the children's biological and behavioral characteristics. The authors therefore encourage strategies that aim to increasing children's physical fitness levels to help prevent excess weight.

Resumo Objetivo Examinar a associação de características individuais e do contexto escolar no índice de massa corporal de crianças portuguesas. Método A amostra compreendeu 1.641 crianças (847 meninos) de 6 a 10 anos. Em relação às características individuais foram utilizadas informações relativas ao sexo, à idade, à residência, à atividade física e à aptidão física. Em termos de contexto escolar, foram considerados o meio ambiente, o tamanho da escola, a presença de recreio, as características e as dimensões do espaço disponível para o recreio, a existência de quadra poliesportiva e de aulas de educação física. O índice de massa corporal [kg/(m2)] foi a variável dependente. A análise multinível foi efetuada no software HLM 7.0. Resultados Os preditores da criança e do contexto escolar explicaram, respectivamente, 97,3% e 2,7% da variância total do índice de massa corporal. Quanto às características individuais, a idade (mais velhos) e o sexo (meninos), bem como o desempenho reduzido nas provas de corrida/marcha da milha, do curl-up, do push-up e valores elevados no trunk lift, estiveram associados ao aumento no índice de massa corporal. Escolas do meio urbano e escolas com maiores espaços para o recreio também estiveram positivamente associadas ao aumento do índice de massa corporal. Conclusões As variáveis do contexto escolar têm um efeito reduzido na variação do índice de massa corporal comparativamente às características biológicas e comportamentais das crianças. Sugere-se a aplicação de programas que visem ao incremento dos níveis de aptidão física das crianças para prevenir o excesso de peso na infância.

Association between body mass index and individual characteristics and the school context: a multilevel study with Portuguese children.

OBJECTIVE: The aim of this study was to examine the association between individual and school context characteristics with the body mass index of Portuguese children. METHODS: The sample comprised 1641 children (847 boys) aged 6-10 years from the North and Central regions of Portugal. Regarding the individual characteristics, age, gender, city of residence, levels of physical activity, and physical fitness were assessed. Concerning the school context characteristics, the surrounding environment, school size, presence of recreational characteristics and space, and presence of a sports court and of physical education classes were considered. Children's body mass index was the dependent variable. The multilevel analysis was carried out in HLM 7.0 software. RESULTS: The predictors of the child and the school context explained, respectively, 97.3% and 2.7% of the total body mass index variance. Regarding the individual characteristics, older children, boys, and those who had lower performance at the 1-mile run/walk, curl-up, push-up, and higher performance in trunk lift tests showed higher BMI. Further, urban schools with higher recreational spaces were positively associated with children's body mass index. CONCLUSION: School context variables have a reduced effect on body mass index variation compared to the children's biological and behavioral characteristics. The authors therefore encourage strategies that aim to increasing children's physical fitness levels to help prevent excess weight.

Joint association of birth weight and physical activity/sedentary behavior with obesity in children ages 9-11 years from 12 countries.

OBJECTIVE: To examine the joint association of birth weight and physical activity/sedentary time with childhood obesity in 12 countries. METHODS: A cross-sectional study of 5,088 children aged 9 to 11 years was conducted. Birth weight was recalled by parents or guardians. Moderate-to-vigorous physical activity (MVPA) and sedentary behavior were objectively measured using accelerometry. RESULTS: The association of birth weight with the odds of obesity, central obesity, and high body fat was significant among children with either low MVPA or high sedentary time but not among children with either high MVPA or low sedentary time. In comparison with children with normal birth weight and high MVPA, children with high birth weight and low MVPA showed 4.48- to 5.18-fold higher odds of obesity, central obesity, and high body fat; children with normal birth weight and low MVPA showed 3.00- to 3.30-fold higher odds of obesity, central obesity, and high body fat, and children with high birth weight and high MVPA showed 1.16- to 1.68-fold higher odds of obesity, central obesity, and high body fat. CONCLUSIONS: High MVPA is more important than high birth weight as a correlate of obesity in children.

Multilevel modelling of somatotype components: the Portuguese sibling study on growth, fitness, lifestyle and health.

BACKGROUND: Somatotype is a complex trait influenced by different genetic and environmental factors as well as by other covariates whose effects are still unclear. AIMS: To (1) estimate siblings' resemblance in their general somatotype; (2) identify sib-pair (brother-brother (BB), sister-sister (SS), brother-sister (BS)) similarities in individual somatotype components; (3) examine the degree to which between and within variances differ among sib-ships; and (4) investigate the effects of physical activity (PA) and family socioeconomic status (SES) on these relationships. SUBJECTS AND METHODS: The sample comprises 1058 Portuguese siblings (538 females) aged 9-20 years. Somatotype was calculated using the Health-Carter method, while PA and SES information was obtained by questionnaire. Multi-level modelling was done in SuperMix software. RESULTS: Older subjects showed the lowest values for endomorphy and mesomorphy, but the highest values for ectomorphy; and more physically active subjects showed the highest values for mesomorphy. In general, the familiality of somatotype was moderate (ρ = 0.35). Same-sex siblings had the strongest resemblance (endomorphy: ρSS > ρBB > ρBS; mesomorphy: ρBB = ρSS > ρBS; ectomorphy: ρBB > ρSS > ρBS). For the ectomorphy and mesomorphy components, BS pairs showed the highest between sib-ship variance, but the lowest within sib-ship variance; while for endomorphy BS showed the lowest between and within sib-ship variances. CONCLUSIONS: These results highlight the significant familial effects on somatotype and the complexity of the role of familial resemblance in explaining variance in somatotypes.

Maternal gestational diabetes and childhood obesity at age 9-11: results of a multinational study.

AIMS/HYPOTHESIS: The aim of this study was to examine the association between maternal gestational diabetes mellitus (GDM) and childhood obesity at age 9-11 years in 12 countries around the world. METHODS: A multinational cross-sectional study of 4740 children aged 9-11 years was conducted. Maternal GDM was diagnosed according to the ADA or WHO criteria. Height and waist circumference were measured using standardised methods. Weight and body fat were measured using a portable Tanita SC-240 Body Composition Analyzer. Multilevel modelling was used to account for the nested nature of the data. RESULTS: The prevalence of reported maternal GDM was 4.3%. The overall prevalence of childhood obesity, central obesity and high body fat were 12.3%, 9.9% and 8.1%, respectively. The multivariable-adjusted (maternal age at delivery, education, infant feeding mode, gestational age, number of younger siblings, child unhealthy diet pattern scores, moderate-to-vigorous physical activity, sleeping time, sedentary time, sex and birthweight) odds ratios among children of GDM mothers compared with children of non-GDM mothers were 1.53 (95% CI 1.03, 2.27) for obesity, 1.73 (95% CI 1.14, 2.62) for central obesity and 1.42 (95% CI 0.90, 2.26) for high body fat. The positive association was still statistically significant for central obesity after additional adjustment for current maternal BMI but was no longer significant for obesity and high body fat. CONCLUSIONS/INTERPRETATION: Maternal GDM was associated with increased odds of childhood obesity at 9-11 years old but this association was not fully independent of maternal BMI.

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.

Variability and Stability in Daily Moderate-to-Vigorous Physical Activity among 10 Year Old Children.

Day-to-day variability and stability of children's physical activity levels across days of the week are not well understood. Our aims were to examine the day-to-day variability of moderate-to-vigorous physical activity (MVPA), to determine factors influencing the day-to-day variability of MVPA and to estimate stability of MVPA in children. The sample comprises 686 Portuguese children (10 years of age). MVPA was assessed with an accelerometer, and BMI was computed from measured height and weight. Daily changes in MVPA and their correlates (gender, BMI, and maturity) were modeled with a multilevel approach, and tracking was calculated using Foulkes &amp; Davies γ. A total of 51.3% of boys and 26.2% of girls achieved 60 min/day of MVPA on average. Daily MVPA was lower during the weekend (23.6% of boys and 13.6% of girls comply with the recommended 60 min/day of MVPA) compared to weekdays (60.8% and 35.4%, boys and girls, respectively). Normal weight children were more active than obese children and no effect was found for biological maturation. Tracking is low in both boys (γ = 0.59 ± 0.01) and girls (γ = 0.56 ± 0.01). Children's MVPA levels during a week are highly unstable. In summary, boys are more active than girls, maturation does not affect their MVPA, and obese children are less likely to meet 60 min/day of MVPA. These results highlight the importance of providing opportunities for increasing children's daily MVPA on all days of week, especially on the weekend.

Why Are Children Different in Their Daily Sedentariness? An Approach Based on the Mixed-Effects Location Scale Model.

This study aimed to investigate the between- and within-individual variability in sedentary time over seven days, using a mixed-effects location scale model. The sample comprised 686 Portuguese children (381 girls) aged 9-11 years, from 23 schools. Sedentary time was estimated by the Actigraph GT3X+ accelerometer, which was used 24 hours/day for 7 consecutive days; height, sitting height, and weight were measured, BMI was computed (WHO cut-points were used to classify subjects as normal weight or overweight/obese), and maturity offset was estimated. Information regarding the home environment was obtained by questionnaire. Results revealed that (i) children were more sedentary on Friday, but less so on Saturday and Sunday (compared to Monday), with significant variation between- and within-subjects (between-subject variance=0.800, within-subject variance=1.793, intra-subject correlation=0.308); (ii) there is a sex effect on sedentariness, with boys being less sedentary than girls (p<0.001), and the between-subject variance was 1.48 times larger for boys than girls; (iii) in terms of the within-subject variance, or erraticism, Tuesday, Wednesday and Friday have similar erraticism levels as Monday (Thursday has less, while Saturday and Sunday have more); in addition, girls (variance ratio=0.632, p<0.001), overweight/obese children (variance ratio=0.861, p=0.019), and those later mature (variance ratio=0.849, p=0.013) have less erraticism than their counterparts; (iv) the within-subject variance varied significantly across subjects (scale std dev=0.342±0.037, p<0.001); and (v) in the fixed part of the model, only biological maturation was positively related to sedentariness. This study demonstrated that there is significant between- and within-subject variability in sedentariness across a whole week. This implies that a focus on intra-individual variability, instead of only on mean values, would provide relevant information towards a more complete map of children's sedentary behaviour, which can be helpful when developing more efficient strategies to reduce sedentariness.

Profiling physical activity, diet, screen and sleep habits in Portuguese children.

Obesity in children is partly due to unhealthy lifestyle behaviours, e.g., sedentary activity and poor dietary choices. This trend has been seen globally. To determine the extent of these behaviours in a Portuguese population of children, 686 children 9.5 to 10.5 years of age were studied. Our aims were to: (1) describe profiles of children's lifestyle behaviours; (2) identify behaviour pattern classes; and (3) estimate combined effects of individual/ socio-demographic characteristics in predicting class membership. Physical activity and sleep time were estimated by 24-h accelerometry. Nutritional habits, screen time and socio-demographics were obtained. Latent Class Analysis was used to determine unhealthy lifestyle behaviours. Logistic regression analysis predicted class membership. About 78% of children had three or more unhealthy lifestyle behaviours, while 0.2% presented no risk. Two classes were identified: Class 1-Sedentary, poorer diet quality; and Class 2-Insufficiently active, better diet quality, 35% and 65% of the population, respectively. More mature children (Odds Ratio (OR) = 6.75; 95%CI = 4.74-10.41), and boys (OR = 3.06; 95% CI = 1.98-4.72) were more likely to be overweight/obese. However, those belonging to Class 2 were less likely to be overweight/obese (OR = 0.60; 95% CI = 0.43-0.84). Maternal education level and household income did not significantly predict weight status (p ≥ 0.05).

Secular trends in growth and nutritional status of Mozambican school-aged children and adolescents.

OBJECTIVES: The purpose of this study was to examine secular changes in growth and nutritional status of Mozambican children and adolescents between 1992, 1999 and 2012. METHODS: 3374 subjects (1600 boys, 1774 girls), distributed across the three time points (523 subjects in 1992; 1565 in 1999; and 1286 in 2012), were studied. Height and weight were measured, BMI was computed, and WHO cut-points were used to define nutritional status. ANCOVA models were used to compare height, weight and BMI across study years; chi-square was used to determine differences in the nutritional status prevalence across the years. RESULTS: Significant differences for boys were found for height and weight (p<0.05) across the three time points, where those from 2012 were the heaviest, but those in 1999 were the tallest, and for BMI the highest value was observed in 2012 (1992<2012, 1999<2012). Among girls, those from 1999 were the tallest (1992<1999, 1999>2012), and those from 2012 had the highest BMI (1999<2012). In general, similar patterns were observed when mean values were analyzed by age. A positive trend was observed for overweight and obesity prevalences, whereas a negative trend emerged for wasting, stunting-wasting (in boys), and normal-weight (in girls); no clear trend was evident for stunting. CONCLUSION: Significant positive changes in growth and nutritional status were observed among Mozambican youth from 1992 to 2012, which are associated with economic, social and cultural transitional processes, expressing a dual burden in this population, with reduction in malnourished youth in association with an increase in the prevalence of overweight and obesity.

Overweight and obesity in Portuguese children: prevalence and correlates.

There are widespread differences in overweight/obesity prevalence in children, and understanding the reasons for this is very important. The present study aims: (I) to conduct a meta-analysis on overweight/obesity prevalence in Portuguese children; (II) to identify differences in biological and behavioural characteristics between normal-weight and overweight/obese children; and (III) to investigate the importance of individual- and school-level correlates of variation in children's BMI using multilevel modelling. A search was done for all published papers including Portuguese children during the last decade; further, 686 Portuguese children (9-11 years old) were sampled and their BMI, family income, maturity offset, nutritional habits, physical activity, sedentariness, sleep time, and school environment information were collected. Results showed a stabilization of overweight/obesity during the last decade, 30.6% (95%CI: 0.287-0.34) for boys, 28.4% (95%CI: 0.23-0.35) for girls, and 30.3% (95%CI: 0.27-0.34) for boys and girls together. Differences between weight groups were only found in individual-level biological traits. The multilevel analysis did not identify significant contributions of school-level variables to children's BMI variation. In conclusion, no increase was found in the prevalence of overweight/obesity among Portuguese children since 2000. Normal-weight and overweight/obese children only differ in individual-level characteristics, and school context variables were not related to variation in BMI.

Secular trends in habitual physical activities of Mozambican children and adolescents from Maputo City.

Social and economic changes occurring in the last two decades in Mozambique may have induced lifestyle changes among youth. This study aimed to document secular changes in habitual physical activities of Mozambican youth between 1992, 1999 and 2012. A total of 3393 youth (eight-15 years), were measured in three different time periods (1992, 1999, 2012). Habitual physical activity (PA) was estimated with a questionnaire, including items related to household chores, sport participation, traditional games and walking activities. Biological maturation was assessed. Analysis of Covariance (ANCOVA) was used to compare mean differences in PA across the years. Significant decreases between 1992-1999 and 1992-2012 were observed for boys in household chores, games and walking, and a significant decline between 1999 and 2012 was found in sport participation. Among girls, a significant and consistent decline (1992 > 1999 > 2012) was observed for household chores, a decline between 1992-1999 and 1992-2012 for games and walking, and a significant increase between 1992 and 1999 in sport participation. In general, a negative secular trend was found in habitual PA among Mozambican youth. Interventions aimed at increasing PA represent important educational and public health opportunities.

Genotype by sex and genotype by age interactions with sedentary behavior: the Portuguese Healthy Family Study.

Sedentary behavior (SB) expression and its underlying causal factors have been progressively studied, as it is a major determinant of decreased health quality. In the present study we applied Genotype x Age (GxAge) and Genotype x Sex (GxSex) interaction methods to determine if the phenotypic expression of different SB traits is influenced by an interaction between genetic architecture and both age and sex. A total of 1345 subjects, comprising 249 fathers, 327 mothers, 334 sons and 325 daughters, from 339 families of The Portuguese Healthy Family Study were included in the analysis. SB traits were assessed by means of a 3-d physical activity recall, the Baecke and IPAQ questionnaires. GxAge and GxSex interactions were analyzed using SOLAR 4.0 software. Sedentary behaviour heritability estimates were not always statistically significant (p>0.05) and ranged from 3% to 27%. The GxSex and GxAge interaction models were significantly better than the single polygenic models for TV (min/day), EEsed (kcal/day), personal computer (PC) usage and physical activty (PA) tertiles. The GxAge model is also significantly better than the polygenic model for Sed (min/day). For EEsed, PA tertiles, PC and Sed, the GxAge interaction was significant because the genetic correlation between SB environments was significantly different from 1. Further, PC and Sed variance heterogeneity among distinct ages were observed. The GxSex interaction was significant for EEsed due to genetic variance heterogeneity between genders and for PC due to a genetic correlation less than 1 across both sexes. Our results suggest that SB expression may be influenced by the interactions between genotype with both sex and age. Further, different sedentary behaviors seem to have distinct genetic architectures and are differentially affected by age and sex.

Multilevel analyses of school and children's characteristics associated with physical activity.

BACKGROUND: Children spend most of their awake time at school, and it is important to identify individual and school-level correlates of their physical activity (PA) levels. This study aimed to identify the between-school variability in Portuguese children PA and to investigate student and school PA correlates using multilevel modeling. METHODS: The sample included 1075 Portuguese children of both sexes, aged 6-10 years, from 24 schools. Height and weight were measured and body mass index (BMI) was estimated. Physical activity was estimated using the Godin and Shephard questionnaire (total PA score was used); cardiorespiratory fitness was estimated with the 1-mile run/walk test. A structured inventory was used to access information about the school environment. A multilevel analysis (level-1: student-level; level-2: school-level) was used. RESULTS: Student-level variables (age, sex, 1-mile run/walk test) explained 7% of the 64% variance fraction of the individual-level PA; however, school context explained approximately 36% of the total PA variance. Variables included in the model (school size, school setting, playground area, frequency and duration of physical education class, and qualification of physical education teacher) are responsible for 80% of the context variance. CONCLUSIONS: School environment is an important correlate of PA among children, enhancing children's opportunities for being active and healthy.

Genotype by energy expenditure interaction with metabolic syndrome traits: the Portuguese healthy family study.

Moderate-to-high levels of physical activity are established as preventive factors in metabolic syndrome development. However, there is variability in the phenotypic expression of metabolic syndrome under distinct physical activity conditions. In the present study we applied a Genotype X Environment interaction method to examine the presence of GxEE interaction in the phenotypic expression of metabolic syndrome. A total of 958 subjects, from 294 families of The Portuguese Healthy Family study, were included in the analysis. Total daily energy expenditure was assessed using a 3 day physical activity diary. Six metabolic syndrome related traits, including waist circumference, systolic blood pressure, glucose, HDL cholesterol, total cholesterol and triglycerides, were measured and adjusted for age and sex. GxEE examination was performed on SOLAR 4.3.1. All metabolic syndrome indicators were significantly heritable. The GxEE interaction model fitted the data better than the polygenic model (p<0.001) for waist circumference, systolic blood pressure, glucose, total cholesterol and triglycerides. For waist circumference, glucose, total cholesterol and triglycerides, the significant GxEE interaction was due to rejection of the variance homogeneity hypothesis. For waist circumference and glucose, GxEE was also significant by the rejection of the genetic correlation hypothesis. The results showed that metabolic syndrome traits expression is significantly influenced by the interaction established between total daily energy expenditure and genotypes. Physical activity may be considered an environmental variable that promotes metabolic differences between individuals that are distinctively active.

Correlation between BMI and motor coordination in children.

OBJECTIVES: To analyze the association between motor coordination (MC) and body mass index (BMI) across childhood and early adolescence. DESIGN: This study is cross-sectional. METHODS: Data were collected in 7175 children (boys n=3616, girls n=3559), ages 6-14 years. BMI was calculated from measured height and weight [body mass (kg)/height (m(2))]. Motor coordination was evaluated using Kiphard-Schilling's body coordination test (KTK). Spearman's rank correlation was used to study the association between BMI and MC. A Kruskal-Wallis test was used to analyze the differences in MC between children of normal weight, overweight and obese children. RESULTS: Correlations between MC and BMI were negative and varied between 0.05 and 0.49. The highest negative correlations for both boys and girls was at 11 years of age. There was a general pattern of increasing negative correlations in both genders from 6 to 11 years of age and then a decrease in correlation strengths through 14 years of age. In both boys (χ(2)((2))=324.01; p<0.001) and girls (χ(2)((2))=291.20; p<0.001) there were significant differences in MC between the three groups' weight status. Normal weight children of both sexes demonstrated significantly higher MC scores than overweight. Obese children in both sexes had the lowest MC scores among all three groups. CONCLUSION: Motor coordination demonstrated an inverse relationship with BMI across childhood and into early adolescence. The strength of the inverse relation increased during childhood, but decreased through early adolescence. Overweight and obese children of both sexes demonstrated significantly lower MC than normal weight children.