Results from Portugal's 2022 report card on physical activity for children and youth.

Background: The purpose of this study is to update results of Portuguese's Report Card on Physical activity (PA) for Children and Adolescents. Methods: The grades were assigned by results derived from the PA and Fitness in Portugal 2021 Portuguese Report Card and corresponds to the third report for the Portuguese children and adolescents. It includes indicators of PA and sedentary behavior (SB) that are common to the GLOBAL matrix 4.0: Overall Physical Activity, Organized Sport and Physical Activity, Active Play, Active Transportation, Sedentary Behaviors, Family and Peers, School, Community and the Environment, Government and Physical Fitness. The search focused on published national evidence/data sources (academia, NGO, governmental) from end 2018 onwards excluding data obtained during the covid-19 pandemic. Results: The grades were assigned as follows: Overall PA (D-), Organized Sport Participation (C-), Active Play (D+), Active Transportation (D-), Sedentary behaviors (C+), Physical Fitness (C), Family and Peers (B), School (A), Community and Environment (B), and Government (B). Conclusion: In line with previous Portuguese Report Cards, a large proportion of Portuguese children and adolescents are not sufficiently active nor fit enough setting urgency for effective strategies. Particular attention should be given to Active play, Active transport and Organized Sports Participation has their grades have decreased. Some actions in selected indicators as Governmental and policy seems promising however results weren't seen yet. Despite the strong support of schools with mandatory curricula in PE no correspondent change is observed in fitness or PA, so more research is needed to find why.

Associations of accelerometer measured school- and non-school based physical activity and sedentary time with body mass index: IPEN Adolescent study.

BACKGROUND: This study examined the strength, shape and direction of associations of accelerometer-assessed overall, school- and non-school-based moderate-to-vigorous physical activity (MVPA) and sedentary time (ST) with BMI among adolescents across the world. Second, we examined whether these associations differed by study site and sex. METHODS: Cross-sectional data from the IPEN Adolescent study, an observational multi-country study, were used. Participants wore an accelerometer for seven days, reported height and weight, and completed a socio-demographic survey. In total, 4852 adolescents (46.6% boys), aged 11-19 years (mean age = 14.6, SD = 1.7 years) were included in the analyses, using generalized additive mixed models. RESULTS: Adolescents accumulated on average 41.3 (SD = 22.6) min/day of MVPA and 531.8 (SD = 81.1) min/day of ST, and the prevalence of overweight and obesity was 17.2% (IOTF), but these mean values differed by country. Linear negative associations of accelerometer-based MVPA and ST with standardized BMI scores and the likelihood of being overweight/obese were found. School-based ST and non-school-based MVPA were more strongly negatively associated to the outcomes than non-school based ST and school-based MVPA. Study site moderated the associations; adolescent sex did not. No curvilinear associations were found. CONCLUSIONS: This multi-country study confirmed the importance of MVPA as a potential protective factor against overweight/obesity in adolescents. Non-school-based MVPA seemed to be the main driver of these associations. Unexpected results were found for ST, calling for further examination in methodologically sound international studies but using inclinometers or pressure sensors to provide more precise ST measures.

Dietary inflammatory index and academic performance in children.

OBJECTIVE: The main aim of the present study was to examine the association between the Dietary Inflammatory Index (DII®) and academic performance in children. DESIGN: School-based cross-sectional study. The DII was calculated based on dietary information obtained from a single 24h dietary recall. Academic performance was assessed by school records provided by the administrative services (i.e. Maths and Language). SETTING: Porto area (Portugal). SUBJECTS: A total of 524 children (277 girls) aged 11·56 (sd 0·86) years. RESULTS: The DII was associated with academic indicators (standardized ß values ranging from -0·121 to -0·087; all P<0·05). Significant differences were found between quartiles of the DII (P<0·05); children in the fourth quartile had significantly lower scores in all academic indicators compared with children in the first quartile (score differences ranging from -0·377 to -0·292) after adjustment for potential confounders. CONCLUSIONS: The inflammatory potential of diet may negatively influence academic performance. Children should avoid the consumption of a pro-inflammatory diet and adhere to a more anti-inflammatory diet to achieve academic benefits.

Waist circumference to height ratio predicts inflammatory risk in children.

BACKGROUND: The increase in obesity, especially the increase of visceral fat, has been directly associated with health risk. Additionally, a waist-to-height ratio (WHtR) (0.5) has been proposed as an indicator of early health risk. AIMS: To test the association between anthropometric measurements and inflammatory mRNA expression and to evaluate the effectiveness of WHtR to predict inflammatory risk in children. SUBJECTS AND METHODS: Anthropometric measurements and fasting blood samples were collected in 94 Brazilian children (46 boys) aged 9-11 years. Children were identified as being at inflammatory risk based on cytokine mRNA expression levels at and above the 75th percentile. Inflammatory cytokine mRNA expression levels were determined through buff-coat using real-time polymerase chain reaction. RESULTS: Body mass index (BMI), waist circumference (WC) and WHtR showed moderate-to-strong association with inflammatory cytokine mRNA gene expression. WHtR = 0.51 was the most accurate cut-off point in distinguishing children at inflammatory risk. Compared with children with WHtR <0.51, children with a WHtR ≥0.51 presented an odds ratio of 2.643 (95% CI = 1.749-3.994) for both diagnosed IL-6 and MCP-1 above the 75th percentile and 2.796 (95% CI = 1.802-4.338) for TNF-α above the 75th percentile. WHtR = 0.50 presented the same values of sensitivity and odds ratio and ∼7% lower specificity compared to WHtR = 0.51. CONCLUSION: Anthropometric measurements have shown a moderate-to-strong association with the mRNA expression of inflammatory genes and a WHtR of 0.5 could serve as a cut-off point, suggesting increased risk of inflammatory responses.

Which social support and psychological factors are associated to active commuting to school?

OBJECTIVE: The aim of this study was to investigate the association between self-efficacy, enjoyment, and volitional control with active commuting, as well as to analyze the impact of social support from parents, friends, and teachers with active commuting to school. METHODS: Participants in this cross-sectional study were 625 students (male: 46.3%) aged 10 to 15years from Porto, Portugal (2010/2011). A questionnaire was used to assess active commuting to/from school (walk/cycle), self-efficacy, enjoyment, volitional control and social support. Binary logistic regression was performed to identify significant associations between targeted variables and active commuting. RESULTS: The results show positive associations in crude analyses for all variables, except for enjoyment for walk/cycle to school. In the adjusted model, higher likelihood of active commuting was found among students who reported having higher self-efficacy (OR=2.10; CI95%: 1.07; 4.11) to walk/cycle to school as well as among adolescents who reported being encouraged by their parents (OR=3.66; CI95%: 1.55; 8.69), and having the partnership of friends in active journeys (OR=4.31; CI95%: 1.79; 10.37). CONCLUSION: Self-efficacy, encouragement from parents and companionship from friends were important indicators of active commuting to school among Portuguese adolescents. These findings provide support for further research to identify and understand factors that predict and explain the active commuting.

Perceived environmental characteristics and psychosocial factors associated with physical activity levels in adolescents from Northeast Brazil: structural equation modelling analysis.

This study aimed to investigate the direct and indirect associations between perceived environmental characteristics and psychosocial factors and physical activity levels in adolescents from Northeast Brazil. The sample was composed of 2,361 adolescents aged 14-19 years (56.6% female). Physical activity was measured using a questionnaire and environmental (perceived environmental characteristics) and psychosocial (self-efficacy, social support from parents and friends for physical activity) factors with previously validated scales. Perceived environmental characteristics were not directly associated with the levels of physical activity, but exhibited significant indirect associations, mediated by self-efficacy in males. Self-efficacy and social support were positively and directly associated with physical activity levels, and part of the associations between social support and physical activity was mediated by self-efficacy. Perception of self-efficacy and social support, important factors associated with physical activity levels in adolescents, should be the target of interventions aimed at increasing physical activity. Favorable environments for physical activity also need to be considered, since they have a positive influence on the self-efficacy of adolescents.

[How to improve active mobility in São Paulo, Brazil? Survey with leaders of nongovernmental organizations and public and private sector managers]. / Como melhorar a mobilidade ativa em São Paulo, Brasil? Inquérito com lideranças de organizações não governamentais e com gestores públicos e privados.

This study aimed to describe a quantitative survey conducted with leaders to investigate effective and feasible actions that can be evaluated in computational models to inform policies to promote active mobility based in the city of São Paulo, Brazil. In 2022, an online survey was conducted during the Health Survey in São Paulo (Physical Activity and Environment study), which is monitored by representatives of nongovernmental organizations and public and private sector managers. A questionnaire was elaborated with three questions with 13 alternative answers about actions to promote walking and/or cycling. Leaders should select up to three alternatives based on their potential regarding: (1) effectiveness; (2) feasibility or ease of implementation; and (3) desire to verify tests in computational models to inform policies. The survey was answered by 18 leaders from 16 institutions, comprising 13 (72%) women and 12 (67%) representatives of the third sector, whose average age was 48 years and all had complete higher education. Reducing the speed of motor vehicles was the most cited option in all three questions. Other actions mentioned refer to controlling the traffic of vehicles in central areas, improving pedestrian safety, reducing the distances between homes and places of employment, conducting educational campaigns, and expanding and enhancing structures such as bicycle lanes and sidewalks. The results are relevant to support evidence-based decision-making in public management and to provide subsidies for the development of computational models with a view to promoting active mobility.

Este estudo teve como objetivo descrever um inquérito quantitativo realizado com lideranças para investigar ações efetivas, viáveis e que podem ser testadas em modelos computacionais para informar políticas de promoção da mobilidade ativa, tendo como base a cidade de São Paulo, Brasil. Em 2022, foi realizado um inquérito online no contexto da pesquisa de Atividade Física e Ambiente do Inquérito de Saúde de São Paulo, acompanhada por representantes de organizações não governamentais, gestores públicos e de entidades privadas. Foi elaborado questionário com três perguntas com 13 alternativas de respostas sobre ações para promoção da caminhada ou uso de bicicleta. As lideranças deveriam selecionar até três alternativas a partir de seu potencial em termos de (1) efetividade; (2) viabilidade ou facilidade de implementação; e (3) desejo de realizar testes em modelos computacionais para informar políticas. O inquérito foi respondido por 18 lideranças de 16 instituições, sendo 13 (72%) mulheres e 12 (67%) representantes do terceiro setor, cuja média de idade era 48 anos, todos com nível superior de escolaridade. A redução da velocidade dos veículos motorizados foi a opção mais citada nas três questões. Outras ações citadas referem-se ao controle de circulação de veículos em regiões centrais, à segurança de pedestres, à diminuição das distâncias entre residências e locais de emprego, às campanhas educativas e à ampliação e melhoria de estruturas como ciclovias e calçadas. Os resultados são relevantes para apoiar a tomada de decisões baseadas em evidências na gestão pública e oferecer subsídios para a elaboração de modelos computacionais com vistas à promoção da mobilidade ativa.

Este estudio tuvo como objetivo presentar una encuesta cuantitativa realizada con líderes para investigar las acciones efectivas, viables y que puedan probarse en modelos informáticos para orientar las políticas que promuevan la movilidad activa en la ciudad de São Paulo, Brasil. En 2022 se realizó una encuesta en línea en el contexto de la Encuesta de Salud de São Paulo (Actividad Física y Medio Ambiente), que es monitoreada por representantes de organizaciones no gubernamentales, gestores públicos y entidades privadas. Se elaboró un cuestionario de tres preguntas con 13 respuestas alternativas sobre acciones para promover la caminata o el uso de la bicicleta. Los líderes podían seleccionar hasta tres alternativas en función de su potencial en términos de (1) efectividad; (2) viabilidad o facilidad de implementación; y (3) deseo de verificar las pruebas en modelos informáticos para orientar las políticas. La encuesta fue respondida por 18 líderes de 16 instituciones; de los cuales 13 (72%) eran mujeres y 12 (67%) representaban el tercer sector; la edad promedio de ellos fue de 48 años y todos contaban con educación superior. Reducir la velocidad de los vehículos de motor fue la opción más citada en las tres preguntas. Otras acciones mencionadas se refieren al control de la circulación de vehículos en las regiones centrales, la seguridad de los peatones, la reducción de las distancias entre los hogares y los lugares de trabajo, las campañas educativas y la expansión y mejora de estructuras como carriles bici y aceras. Los resultados son relevantes para apoyar la toma de decisiones basada en la evidencia en la gestión pública y ofrecer subsidios para la elaboración de modelos computacionales destinados a promover la movilidad activa.

Is walking to school associated with improved metabolic health?

BACKGROUND: Active commuting to/from school is an important source of physical activity that has been declining over the past years. Although it is an affordable and simple way of increasing physical activity levels it is still unclear whether it has enough potential to improve health. Therefore, the aim of this cross sectional study was to examine the relationship between active commuting to/from school and metabolic risk factors in 10 to 12 year old children. METHODS: Participants were 229 adolescents, selected through consecutive sampling, (121 girls) with mean age of 11.65 (±0.73) years old from Porto, Portugal. Means of transport to/from school was accessed by asking: "How do you usually travel to school?" and "How do you usually travel from school?". Active commuting was considered if children reported at least one of the trips (to or from school) by active means. Total physical activity was obtained with Actigraph accelerometer for 7 consecutive days. Lipid profile measurements were conducted with Cholestech LDX® analyser. Waist circumference and blood pressure were measured by standard methods. The criteria for metabolic syndrome defined by International Diabetes Federation for children and adolescents were used. RESULTS: Adjusted binary logistic regression analysis suggested that walkers have higher odds to have a better waist circumference (OR = 2.64, 95% CI = 1.63-6.01) and better high density lipoprotein cholesterol (OR = 2.14, 95% CI = 1.01-4.52) profiles than non-active commuters, independent of moderate-to-vigorous physical activity. No associations were found for other metabolic risk factors. CONCLUSIONS: Exertions to increase and maintain walking to school may be particularly relevant as it is likely to have a positive impact on children's health and eventually decrease metabolic and cardiovascular diseases.

Cross validation of ROC generated thresholds for field assessed aerobic fitness related to weight status and cardiovascular disease risk in Portuguese young people.

OBJECTIVES: To examine the efficacy of aerobic fitness thresholds in predicting weight status and cardiovascular disease risk (CVD) in young people. METHODS: A cross-sectional school-based study was conducted on 414 Portuguese young people (235 girls and 179 boys) aged 10-16 years (Mean age ± SD = 13.6 ± 1. 8 years). Height and mass were assessed to determine body mass index (BMI). The 20 m multistage shuttle-fitness test (MSFT) was used as an estimate of aerobic fitness. Capillary blood sampling was used to determine: total cholesterol, triglycerides, high-, and low-density lipoprotein. These were combined with measures of systolic blood pressure as z-scores and summed to create a CVD risk score. RESULTS: Analysis of covariance, controlling for sexual maturation, indicated a significant main effect for BMI as a result of fitness category (P = 0.0001). When applied to CVD risk data, there was no difference between "fit" and "unfit" groups (P = 0.136). Subsequent receiver operating curve (ROC) analysis indicated significant diagnostic accuracy of 20 mMSFT performance for boys and girls (both P = 0.0001) with subsequent cut-offs of estimated VO2 peak of 49.5 ml kg(-1) min(-1) for girls and 47.7 ml kg(-1) min(-1) for boys. When applied to BMI and CVD risk data, there was a significant main effect as a result of fitness category for BMI (P = 0.0001) and CVD risk score (P = 0.0001). CONCLUSIONS: Recently established cut-points proposed by Boddy et al. (Boddy et al. [2012]: PLoS One 7(9): e45755) show validity in distinguishing between weight status but not CVD risk in Portuguese young people. Alternative ROC generated cut points significantly predicted BMI and CVD risk in this sample.

Parental physical activity, safety perceptions and children's independent mobility.

BACKGROUND: Parents are likely to be a basic influence on their children's behavior. There is an absence of information about the associations between parents' physical activity and perception of neighborhood environment with children's independent mobility.The purpose of this study is to examine the contribution of parental physical activity and perception of neighborhood safety to children's independent mobility. METHODS: In this cross-sectional study of 354 pupils and their parents, independent mobility, perceptions of neighborhood safety and physical activity were evaluated by questionnaire. Categorical principal components analyses were used to determine the underlying dimensions of both independent mobility and perceptions of neighborhood safety items. RESULTS: The strongest predictor of independent mobility was the parental perception of sidewalk and street safety (beta = 0.132). Parent's physical activity was also a significant predictor. The final model accounted for 13.0% of the variance. CONCLUSIONS: Parental perception of neighborhood safety and parents' self reported physical activity might be associated with children's independent mobility. Further research in this topic is needed to explore this possible association.

Cardiorespiratory fitness, but not central obesity or C-reactive protein, is related to liver function in obese children.

UNLABELLED: Nonalcoholic fatty liver disease (NAFLD) is one of the most frequent complications associated with excess adiposity. Its pathogenesis is complex and there are multiple factors that may contribute to it. AIM: To analyze whether cardiorespiratory fitness (CRF), waist circumference (WC), and C-reactive protein (CRP) are associated with alanine aminotransferase (ALT) in children with obesity. METHODS: 79 overweight/obese children of both genders, 11-13 year-olds, with abnormal serum ALT from Porto public schools comprised the sample. Measurements included CRF (20-m Shuttle Run Test), WC (NHANES protocol), CRP and ALT (Cholestech LDX analyzer). Logistic regression adjusted for gender, maturation, and weight with ALT levels as dependent variable (risk vs. non risk), and WC (risk vs. non risk), CRP (risk vs. non risk), and CRF (fit vs. unfit) as independent variables. Level of significance was set at 95%. RESULTS: Logistic regression showed that obese fit children were less likely to have abnormal ALT values (OR=.031) CONCLUSION: In obese children, higher cardiovascular fitness appears to reduce the chance of decreased liver function.

Associations between body mass index, waist circumference and body shape index with resting blood pressure in Portuguese adolescents.

BACKGROUND: Elevated blood pressure (BP) in childhood and adolescence is associated with overweight and obesity. Recently a body shape index (ABSI) has been suggested as superior to body mass index (BMI, kg/m(2)) and waist circumference (WC) as a measure of disease risk. OBJECTIVE: To examine the association between ABSI, BMI, WC and BP in Portuguese adolescents and to consider the role of ABSI, BMI and WC when examining this issue in adolescents. METHODS AND PROCEDURES: Height, body mass, WC and resting blood pressure were assessed in 445 Portuguese adolescents (252 girls and 193 boys) aged 10-17 years. RESULTS: ABSI, BMI and WC were all significantly related to both SBP and DBP (all p = 0.001 or better). ABSI, BMI and WC were all significant predictors of SBP and DBP for the whole sample and when analysed in separate gender groups (p = 0.001 or better in all cases). However, in all cases ABSI was a better predictor of BP than BMI or WC. CONCLUSIONS: Although BMI and WC significantly predict resting BP in adolescents, the use of ABSI explained a greater amount of the variance in BP in this population. When examining the effect of weight status on BP, researchers should consider use of ABSI alongside BMI.

Fitness and metabolic syndrome in obese fatty liver children.

BACKGROUND: Metabolic Syndrome (MS) is highly prevalent among obese children with fatty liver. However, it is well-known that there is a lower prevalence of MS in individuals with higher cardiorespiratory fitness (CRF). AIM: To analyse the association between CRF with features of the MS in obese children that present fat liver indicators, namely abnormal alanine aminotransferase (ALT) values. METHODS: A total of 79 obese students (40 girls), 10-11 year-olds ( ± 0.60), with abnormal serum ALT from Porto public schools comprised the sample. Measurements included CRF (20-metre Shuttle Run Test), Metabolic Risk Factors (MRF), according to MS International Diabetes Federation criteria, ALT values (Cholestech LDX(®) analyser) and maturational stage (Tanner criteria). Logistic regression analysis was used to determine the influence of CRF on MRF adjusted for sex, maturation, and BMI. RESULTS: The logistic regression showed that, despite being classified as being obese and presenting abnormal levels of ALT, those classified as fit were less likely to have MS than their unfit counterparts (OR = 0.52; p ≤ 0.05). CONCLUSION: Obese-fit children with abnormal ALT values have a significant reduction in the likelihood to be classified as having MS, even after adjustments for gender, maturation and BMI, Thus, CRF might be an important factor for tackling fatty liver among obese.

Cardiorespiratory fitness and TV viewing in relation to metabolic risk factors in Portuguese adolescents.

BACKGROUND: The purpose of this study was to examine whether adolescents who have high levels of cardiorespiratory fitness (CRF) co-existing with low levels of television (TV) viewing present a better metabolic risk profile compared to their low fit and high TV viewing counterparts. SUBJECTS AND METHODS: A total of 372 students (aged 12-15 years old) comprised the sample of this study. Anthropometric data (body mass index and waist circumference) was collected. CRF was calculated based upon the 20 metres shuttle run test. A questionnaire was used to estimate weekly TV viewing. Information about biological maturity and parental education was collected. Participants were then categorized into one of four category profiles according to the scores they achieved: low TV-Fit; high TV-Fit; low TV-Unfit and high TV-Unfit. Metabolic risk score (MRS) was calculated based on the sum of the Z-scores of all the metabolic variables analysed. RESULTS: Logistic regression analyses indicated that the high TV-Unfit group was almost 3-times more likely to be assigned to the high MRS group (OR = 2.85, 95% CI = 1.08-7.50) compared to their low TV-Fit group counterparts. CONCLUSIONS: The data showed that the high TV-Unfit group was associated with an increased metabolic risk in adolescents after adjustment for gender, age, biological maturity and parental education.

Comparisons between inverted body mass index and body mass index as proxies for body fatness and risk factors for metabolic risk and cardiorespiratory fitness in Portuguese adolescents.

OBJECTIVES: To compare inverted body mass index (iBMI, cm(2) /kg) and body mass index (BMI, kg/m(2) ) as predictors of body fatness, metabolic risk, and cardiovascular fitness in adolescents. METHODS: A cross-sectional school-based study was conducted on 445 Portuguese adolescents (252 girls and 193 boys) aged 10-17 years. Height and body mass were assessed to determine iBMI and BMI, percent body fatness was determined from skinfold measures (tricep, subscapular) using the Slaughter et al. (1988: Hum Biol 60: 709-723) regression equation and cardiorespiratory fitness (CRF) was assessed using the 20-m shuttle run test. Capillary blood sampling was used to determine: Total cholesterol, triglycerides, high, and low density lipoprotein. These were combined with measures of systolic blood pressure and waist circumference as z-scores. Metabolic risk (MRS) was constructed by summing the z-scores. RESULTS: iBMI and BMI were both significantly related to percent body fatness, CRF and MRS (all P = 0.005 or better). BMI was not normally distributed (P = 0.0001), whereas iBMI was (P > 0.05). Regression analysis identified that iBMI and BMI, both alongside for age, were significant predictors of percent body fatness, CRF and MRS (all P = 0.005 or better). Compared with BMI, iBMI was a similar predictor of CRF, MRS and body fatness. CONCLUSIONS: iBMI offers a biologically sound alternative to BMI to assess the effect of weight status on MRS and CRF in adolescents and allows appropriate use of parametrical statistical techniques without changing the conclusions drawn from such data.

Perception of the social and built environment and physical activity among Northeastern Brazil adolescents.

OBJECTIVE: To evaluate the association between levels of physical activity and perception of the social and built environmental in adolescents from Northeastern Brazil. METHODS: The sample comprised 2874 adolescents aged 14 to 19 years (57.8% females) enrolled in private or public secondary schools in the municipality of João Pessoa, Northeastern Brazil. Level of physical activity was measured by questionnaire. Perception of environmental characteristics was measured by means of fifteen questions rated on four-point Likert-type scales ranging from 1 ("strongly disagree") to 4 ("strongly agree"). The association between physical activity and perception of environmental characteristics was investigated using multivariate binary logistic regression. RESULTS: Multivariate analysis showed that adolescents living in neighborhoods where other adolescents were physically active (68.7% vs. 60.1%, OR=1.20; 95%CI: 1.05-1.56, among boys only) or who lived close to places they liked to frequent (71.8% vs. 53.4%, OR=1.96; 95%CI: 1.40-2.78 among boys; and 42.0% vs. 32.3% OR=1.33; 95%CI: 1.10-1.74 among girls) were more likely to be physically active. CONCLUSIONS: Adolescents with positive perceptions of certain environmental characteristics were more likely to be physically active. Environmental characteristics may relate differently to levels of physical activity among boys and girls.

Perceived neighbourhood environmental characteristics and physical activity according to socioeconomic status in adolescent girls.

OBJECTIVE: The purpose of this study was to analyse the associations between physical activity (PA) and several characteristics of the built environment with socioeconomic status (SES) in adolescent girls. METHODS: The sample comprised 599 girls (mean age 14.7, SD = 1.6 years) living in the Aveiro Region of Portugal. Questionnaires were used to describe physical activity level and perceived neighbourhood environments. SES was established by maternal education level. Girls were grouped into low, middle or high SES group. RESULTS: Logistic regression analysis showed that girls assigned to the higher SES group were more likely (OR = 2.4; 95%CI = 1.3-4.5) to belong to the active group than their low SES peers. Girls in high (OR = 2.4; 95%CC = 1.3-4.4) and medium (OR = 1.6; 95%CC = 1.14-2.3) SES groups were more likely to have a higher perception of better aesthetics in their neighbourhoods than their low SES peers and higher SES was also associated with better perception of a street connectivity (OR = 2.9; 95%CI = 1.7-5.4). CONCLUSION: The study showed that girls of higher SES are more active than those of lower SES and that social background might be associated with differences in neighbourhood environmental perceptions.

Urban Green Spaces, Greenness Exposure and Species Richness in Residential Environments and Relations with Physical Activity and BMI in Portuguese Adolescents.

Environmental factors play an important role in obesity-related behaviors. Evidence indicates significant associations between weight and urban green spaces in adults, but it is not clear whether this relationship applies to adolescents. Therefore, our aim was to determine the associations between urban green spaces, greenness exposure and species richness in residential environments with physical activity and body mass index. Sixty-two adolescents between 12 and 18 years of age answered a self-administered questionnaire, providing information on height, weight, age, sex and home address. Data on socioeconomic deprivation were obtained from the European Index of Deprivation for Small Portuguese Areas. Physical activity levels were assessed using accelerometers. Urban green space counts and the normalized difference vegetation index values were measured using buffers along the roads with distances of 300, 500, 1000 and 1500 m from each participant's residence. To quantify the species richness, the species richness index was used. Linear regression models were fitted to analyze whether urban green spaces, exposure to green spaces and species richness counts for each distance were associated with physical activity and self-reported body mass index. We did not find significant associations between the independent variables and the probability of overweight or obesity. The relationship between environmental variables, adolescents' physical activity and body weight seems to be complex and further studies may contribute to better understanding of the topic.

The effect of impact exercise on bone mineral density: A longitudinal study on non-athlete adolescents.

PURPOSE: High impact exercise is known to induce osteogenic effects in the skeleton. However, less is known about the systemic effect of exercise practice in a potential adaptive mechanism of the skeletal accrual. This research aimed to assess the effect of impact exercise on bone mineral density (BMD) in the radius throughout adolescence. METHODS: This study evaluated 1137 adolescents, at 13 and 17 years old, as part of the population-based cohort EPITeen. BMD (g/cm2) was measured at the ultradistal and proximal radius of the non-dominant forearm by dual-energy X-ray absorptiometry (DXA) using a Lunar® Peripheral Instantaneous X-ray Image device. The practice of (extra-curricular) exercise was categorized as: no exercise, exercise with high impact and exercise with low impact. Regression coefficients (ß) and respective 95% confidence intervals (CI95%) were used to estimate the association between exercise practice categories at 13 years old and BMD at 13 and 17 years old and BMD gain between evaluations. RESULTS: In boys, at 13 years, BMD was similar between the ones not practicing exercise and those practicing exercise with low impact, and the gain of BMD was also similar in both groups. Still in boys, at 13 years, those who practiced exercise with high impact presented higher mean (standard-deviation) of BMD, comparing to the other two groups (no exercise and low impact exercise), and also significantly increased the BMD gain between 13 and 17 years (ß = 0.013; CI95%0.003;0.023). In girls, no statistically significant differences on BMD were found between the categories of exercise at 13 years and BMD at 17 years of age. CONCLUSION: This research shows that the practice of high impact exercise could help to increase BMD more than low impact exercise even in a nonweight-bearing bone during adolescence.

International Physical Activity and Built Environment Study of adolescents: IPEN Adolescent design, protocol and measures.

INTRODUCTION: Only international studies can provide the full variability of built environments and accurately estimate effect sizes of relations between contrasting environments and health-related outcomes. The aims of the International Physical Activity and Environment Study of Adolescents (IPEN Adolescent) are to estimate the strength, shape and generalisability of associations of the community environment (geographic information systems (GIS)-based and self-reported) with physical activity and sedentary behaviour (accelerometer-measured and self-reported) and weight status (normal/overweight/obese). METHODS AND ANALYSIS: The IPEN Adolescent observational, cross-sectional, multicountry study involves recruiting adolescent participants (ages 11-19 years) and one parent/guardian from neighbourhoods selected to ensure wide variations in walkability and socioeconomic status using common protocols and measures. Fifteen geographically, economically and culturally diverse countries, from six continents, participated: Australia, Bangladesh, Belgium, Brazil, Czech Republic, Denmark, Hong Kong SAR, India, Israel, Malaysia, New Zealand, Nigeria, Portugal, Spain and USA. Countries provided survey and accelerometer data (15 countries), GIS data (11), global positioning system data (10), and pedestrian environment audit data (8). A sample of n=6950 (52.6% female; mean age=14.5, SD=1.7) adolescents provided survey data, n=4852 had 4 or more 8+ hours valid days of accelerometer data, and n=5473 had GIS measures. Physical activity and sedentary behaviour were measured by waist-worn ActiGraph accelerometers and self-reports, and body mass index was used to categorise weight status. ETHICS AND DISSEMINATION: Ethical approval was received from each study site's Institutional Review Board for their in-country studies. Informed assent by adolescents and consent by parents was obtained for all participants. No personally identifiable information was transferred to the IPEN coordinating centre for pooled datasets. Results will be communicated through standard scientific channels and findings used to advance the science of environmental correlates of physical activity, sedentary behaviour and weight status, with the ultimate goal to stimulate and guide actions to create more activity-supportive environments internationally.