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Background: Leptin and adiponectin interact with each other in the modulation of obesity and insulin resistance (IR) and it is also important to consider the role of cardiorespiratory and muscular fitness in these relationships. Aim : To analyse the relationship between IR with adipocytokines in children, and to test the mediation effect of %BF (percentage of body fat) in the association of IR with leptin, adiponectin, and L/A ratio. Subjects and methods: This cross-sectional study comprised a sample of 150 schoolchildren, aged 6-11 years, from school in Porto Alegre, Brazil. The following variables were evaluated: cardiorespiratory fitness (CRF), muscular fitness (MF), percentage of body fat (%BF), and biochemical variables (leptin, adiponectin, glucose, and insulin). Results: IR was associated with leptin and L/A ratio, after adjustments for age, sex, sexual maturation, and CRF. When adjusted for age, sex, sexual maturation, and MF, an association was found between IR with leptin and L/A ratio. Moreover, %BF was a mediator in the association between IR and leptin, as well as IR and L/A ratio, explaining 54% and 57% of these associations, respectively. Conclusion: Leptin and L/A ratio are positively associated with IR after adjustments. Also, %BF is a mediator in the associations between IR and leptin and L/A ratio.

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.

Background: Cardiorespiratory fitness (CRF) and physical activity (PA) seem to have positive effects on academic achievement (AA), although in most studies, objective methods of assessment have not been used., Aim: To examine the associations of CRF and PA with AA., Subjects and Methods: A sample of 640 youngsters (10-18 years) participated in this cross-sectional study. CRF was estimated with the 20-metre shuttle run test and PA was measured using accelerometers. School grades were used to describe AA using mathematics and native language final grades. The relationship between CRF and PA with AA was analysed using ANCOVA., Results: Results show a significant effect of CRF levels on native language grades, after adjustment for confounders [F(3,414) = 3,99 p < 0.05], but not for mathematics [F(3,360) = 0.95 p > 0.05]. No significant effects of PA levels on AA were found., Conclusions: CRF is associated with moderate-to-vigorous PA (MVPA) and higher levels of CRF may influence AA. CRF is positively correlated with MVPA, suggesting that higher amounts of MVPA might improve CRF and indirectly influence AA. Since CRF is dependent on higher intensities of PA, we can suggest a focus on implementing improvement strategies to increase the intensity of physical education lessons.

Background: The use of step count and TV viewing time to discriminate youngsters with hyperglycaemia is still a matter of debate., Aim: To establish cut-off values for step count and TV viewing time in children and adolescents using glycaemia as the reference criterion., Subjects and Methods: A cross-sectional study was conducted on 1044 schoolchildren aged 6-18 years from Northeastern Brazil. Daily step counts were assessed with a pedometer over 1 week and TV viewing time by self-report., Results: The area under the curve (AUC) ranged from 0.52-0.61 for step count and from 0.49-0.65 for TV viewing time. The daily step count with the highest discriminatory power for hyperglycaemia was 13 884 (sensitivity = 77.8; specificity = 51.8) for male children and 12 371 (sensitivity = 55.6; specificity = 55.5) and 11 292 (sensitivity = 57.7; specificity = 48.6) for female children and adolescents respectively. The cut-off for TV viewing time with the highest discriminatory capacity for hyperglycaemia was 3 hours/day (sensitivity = 57.7-77.8; specificity = 48.6-53.2)., Conclusion: This study represents the first step for the development of criteria based on cardiometabolic risk factors for step count and TV viewing time in youngsters. However, the present cut-off values have limited practical application because of their poor accuracy and low sensitivity and specificity.

Aim: To determine the effects of a school-based exercise intervention programme on cardiovascular risk factors, including body fat (BF), metabolic profile and physical activity (PA) in children with and without individualised dietary counselling approach (IDC and WIDC)., Subjects and Methods: Forty-six overweight children from 6-16 years old (25 girls, 54.3%; age = 10.3 ± 2.8) of six schools took part in an 8-month interdisciplinary, school-based intervention programme. All children were engaged in PA classes, but only one group was exposed to individualised counselling. Blood pressure (BP), lipids and lipoproteins, accelerometer-based PA, percentage of body fat (%BF) and trunk fat (%TF) measures were taken before and after intervention. General Linear Model (Repeated Measures ANOVA) adjusted for age, maturation and height change was used to analyse the longitudinal effect of individualised counselling between two evaluations in each group., Results: Favourable changes were observed for %BF, %TF, systolic BP and total cholesterol in the IDC group. Subjects WIDC only increased light and moderate-vigorous PA. In IDC, significant effects for time * group interactions were found for systolic BP, total cholesterol and LDL-cholesterol, indicating that counselling might add favourable changes in these markers, beyond those explained by PA and growth., Conclusion: School-based interventions can contribute to counteracting obesity in youth, particularly when individualised dietary counselling is provided. Therefore, the link between schools and professional counselling should be strengthened to ensure consolidated changes towards healthy behaviours.

Background: There is clear evidence that environmental factors play an important role regarding physical activity (PA) and sedentary behaviour (SB) in youth. This short report highlights seasonal differences in the amount and intensities of PA and SB, in Portuguese youth., Methods: Three hundred and eighty-seven participants (aged 14.7 ± 1.9 years), 220 girls, used the Actigraph GT1M accelerometer for 7 days (15-second epochs), between January and June in 2008. PA and SB differences were assessed using an ANCOVA., Results: Boys had significantly higher values of PA, with the exception of Light intensity. Girls were significantly more sedentary. PA intensities and SB changed significantly according to gender and month of assessment. SB (Gender F = 16.32, p < 0.001; Month F = 2.95, p < 0.013), Light PA (Gender F = 9.30, p = 0.002; Month F = 8.37, p < 0.001; Gender*Month F = 2.24, p = 0.050), Moderate PA (Gender F = 40.04, p < 0.001), Vigorous PA (Gender F = 32.89, p < 0.001; Month F = 2.56, p = 0.027). Both genders increased PA from winter to summer months and SB decreased., Conclusions: Seasonality in PA intensities and SB suggest that interventions to promote PA and decrease SB must be tailored to take into consideration the month of the year they are going to be implemented and also gender characteristics.

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.

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.

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.

Background: Improving physical fitness is often an objective of programmes aimed at preventing obesity among youth., Aim: To evaluate the association between cardiorespiratory fitness (CRF) and area of residence controlling for several correlates in adolescents., Subjects and Methods: CRF was assessed with the progressive aerobic cardiovascular endurance run (PACER) test in a cross-sectional sample of 362 Portuguese adolescents (165 males, 197 females) of 13-16 years of age. Youth were classified by area of residence as urban or rural. Gender, age, weight status, parental education, screen time (inactivity) and moderate-to-vigorous physical activity (MVPA) were statistically controlled. Logistic regression analysis was used., Results: Adolescents of both sexes from rural settings were 76% more likely to be classified as aerobically fit compared to those from urban areas. The odds ratio for CRF in the final model was similar in boys (OR = 0.24, 95% CI 0.06-0.99, p < 0.05) and girls (OR = 0.24, 95% CI 0.07-0.76, p < 0.05). MVPA and weight status were important predictors of CRF in Portuguese adolescents of 13-16 years of age. Maternal education was an additional predictor in girls., Conclusion: CRF and rural/urban settings were significantly related in this sample of Portuguese adolescents of both sexes.

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.

Background: Elevated blood pressure (BP) has been reported in young people and seems to be associated with body mass index (BMI) and reduced physical activity (PA)., Aim: This study sought to analyse the association of BP with BMI, PA intensity patterns and cardiorespiratory fitness (CRF) in youth., Subjects and Methods: A cross-sectional study was carried out including 66 boys (13.91+/-1.76) and 97 girls (14.02+/-1.71). Anthropometric characteristics, CRF and BP were assessed during school time and accelerometers were utilized to determine intensity of PA., Results: The linear regression model, adjusted for age, sex and height, showed that higher values of BMI were associated (p

Objective: The purpose of this study was to assess the associations and impact of increased meal frequency, physical activity and 'skipping' breakfast on obesity levels in a sample of urban adolescents, aged 13-17 years old, from Porto, Portugal., Methods: Overweight and obesity were defined according to age- and sex-specific BMI cut-points. Daily meal frequency was assessed by questionnaire. Self-reported physical activity was recalled., Results: The proportion of overweight/obese girls (p < or = 0.05) and boys (p < or = 0.001) that consumed fewer than three meals was significantly higher than those reported from normal-weight counterparts. While no statistically significant differences were reported in girls, obese boys skipped breakfast significantly more (13% vs 5.6%; p < or = 0.05) than normal-weight counterparts did. Normal-weight boys but not girls were significantly more active (p < or = 0.01) than obese peers. An additional meal in boys (OR: 2.75; p < or = 0.05) and girls (OR: 1.97; p < or = 0.05) reduced the risk of being overweight/obese. Regardless of gender, breakfast skipping is not seen as a predictor of being overweight/obese. However, boys (OR: 2.10; p < 0.003), but not girls, who were moderately active were more likely to be of normal weight., Conclusion: The data indicate that increased meal frequency may have a beneficial effect on a reduced BMI. Physical activity and breakfast skipping may be candidate targets for prevention programmes aimed at reducing overweight/obesity among adolescents.

Objective: The aims of this study were (1) to assess the relationships between transport to and from school (active vs. passive), sedentary behaviours, measures of socio-economic position and perceived environmental variables, and (2) to determine which, if any, variables were predictors of active transportation., Methods: The sample comprised 705 girls with mean age of 14.7 (SD = 1.6) years old. Questionnaires were used to describe travel mode to school and to estimate weekly television and computer use (screen time). Girls were assigned to active transportation (AT) or passive transportation (PT) groups depending on whether they walked or bicycled (AT) to and from school or travelled by car or bus (PT). Screen time was determined by the number of hours they reported watching television and using computers in the week preceding the examination, including weekends. Socio-economic position was established by parental occupation and educational level. A questionnaire assessed Perceived Neighbourhood Environments., Results: No statistically significant differences were seen for screen time between travel groups. Occupational status of both mother (r = -0.17) and father (r = -0.15) and father's educational level (r = -0.10) were significantly and negatively associated with AT, while street connectivity (r = 0.10) was positively and significantly associated with AT. Logistic regression analysis showed that the likelihood of active commuting decreased by around 50% with increasing father's occupation (odds ratio (OR) = 0.51; p