Interplay of physical activity and genetic variants of the endothelial lipase on cardiovascular disease risk factors.

BACKGROUND: The aim of this study was to investigate the association of endothelial lipase gene (LIPG) polymorphisms with cardiovascular disease (CVD) risk factors in adolescents and their interaction with physical activity. METHODS: Six polymorphisms of LIPG were genotyped in 1057 European adolescents (12-18 years old) enrolled in the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) Study. CVD risk factors related to lipid profile, blood pressure, adiposity and glucose regulation were recorded. Physical activity was objectively measured by accelerometry. RESULTS: The major C allele of rs2000813, the minor T allele of rs2276269 and the minor G allele of rs9951026 were associated with lower levels of several CVD risk factors related to lipid profile. We also found a significant association of the TTACA LIPG haplotype (rs2000812, rs2000813, rs8093249, rs2276269 and rs9951026) with higher concentrations of low-density cholesterol and apolipoprotein B. Finally, the interaction between physical activity and the polymorphisms rs2000813, rs2276269 and rs9951026 had a significant influence on several CVD risk factors. CONCLUSIONS: LIPG polymorphisms were significantly associated with CVD risk factors in European adolescents. Interestingly, alleles of these polymorphisms were associated with a better cardiovascular profile in physically active adolescents only. High physical activity may reduce the development of CVD, modulating its genetic risk. IMPACT: Using gene-phenotype and gene × environment analyses, we detected associations between the endothelial lipase gene and cardiovascular risk factors, along with interactions with physical activity. This study shows that physical activity may modulate the influence of LIPG gene on cardiovascular risk in adolescents. These results bring insights into the mechanisms by which physical activity positively influences CVD in adolescents.

High Fructose Intake Contributes to Elevated Diastolic Blood Pressure in Adolescent Girls: Results from The HELENA Study.

BACKGROUND: The association between high fructose consumption and elevated blood pressure continues to be controversial, especially in adolescence. The aim of this study was to assess the association between fructose consumption and elevated blood pressure in an European adolescent population. METHODS: A total of 1733 adolescents (mean ± SD age: 14.7 ± 1.2; percentage of girls: 52.8%) were analysed from the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study in eight European countries. Blood pressure was measured using validated devices and methods for measuring systolic blood pressure (SBP) and diastolic blood pressure (DBP). Dietary data were recorded via repeated 24 h recalls (using specifically developed HELENA-DIAT software) and converted into pure fructose (monosaccharide form) and total fructose exposure (pure fructose + fructose from sucrose) intake using a specific fructose composition database. Food categories were separated at posteriori in natural vs. were non-natural foods. Elevated BP was defined according to the 90th percentile cut-off values and was compared according to tertiles of fructose intake using univariable and multivariable mixed logistic regression models taking into account confounding factors: centre, sex, age and z-score-BMI, MVPA (Moderate to Vigorous Physical Activity) duration, tobacco consumption, salt intake and energy intake. RESULTS: Pure fructose from non-natural foods was only associated with elevated DBP (DBP above the 10th percentile in the highest consuming girls (OR = 2.27 (1.17-4.40); p = 0.015) after adjustment for cofounding factors. CONCLUSIONS: Consuming high quantities of non-natural foods was associated with elevated DBP in adolescent girls, which was in part due to high fructose levels in these foods categories. The consumption of natural foods containing fructose, such as whole fruits, does not impact blood pressure and should continue to remain a healthy dietary habit.

Severe preschool asthmatics have altered cytokine and anti-viral responses during exacerbation.

BACKGROUND: Preschool asthma/recurrent wheeze is a heterogeneous condition. Different clinical phenotypes have been described, including episodic viral wheeze (EVW), severe intermittent wheeze (SIW), and multiple-trigger wheeze (MTW). OBJECTIVE: To compare clinical, viral, and inflammatory/immune profiling at exacerbation between MTW, SIW, and EVW phenotypes. METHODS: Multicenter, prospective, observational cohort (VIRASTHMA-2). Children (1-5 years) with preschool asthma were enrolled during hospitalization for a severe exacerbation. History and anamnestic data, plasma, and nasal samples were collected at exacerbation (T1) and at steady state, 8 weeks later (T2), and sputum samples were collected at T1. RESULTS: A total of 147 children were enrolled, 37 (25%) had SIW, 18 (12.2%) EVW, and 92 (63%) MTW. They were atopic (47%), exposed to mold (22%) and cigarette smoke (50%), and prone to exacerbations (≥2 in the previous year in 70%). At exacerbation, at least one virus was isolated in 94% and rhinovirus in 75%, with no difference between phenotypes. Children with MTW and SIW phenotypes displayed lower plasma concentrations of IFN-γ (P = .002), IL-5 (P = .020), TNF-α (P = .038), IL-10 (P = .002), IFN-ß (P = .036), and CXCL10 (P = .006) and lower levels of IFN-γ (P = .047) in sputum at exacerbation than children with EVW. At T2, they also displayed lower plasma levels of IFN-γ (P = .045) and CXCL10 (P = .013). CONCLUSION: Among preschool asthmatic children, MTW and SIW, prone to exacerbations, display lower systemic levels of Th1, Th2 cytokines, pro- and anti-inflammatory cytokines, and antiviral responses during severe virus-induced exacerbation.

Influence of meteorological conditions on physical activity in adolescents.

BACKGROUND: It has been shown that meteorological conditions and season affect physical activity (PA) during adolescence. Today, meteorological conditions have never been combined to study their influence on PA level in a single sample of a large adolescent multicountries population. The aim of this study was to explore the influence of meteorological conditions on PA in adolescents from several European countries. METHODS: The study included 2024 healthy adolescents aged 12.5-17.4 years who participated in the Healthy Lifestyle in Europe by Nutrition in Adolescence cross-sectional study. Participants wore a uniaxial accelerometer for 7 consecutive days to measure total PA and moderate to vigorous physical activity (MVPA) in a one-off measurement manner. Comparison of PA according to meteorological conditions was done using linear mixed models. RESULTS: The highest difference of MVPA was observed in boys on free days when comparing the best meteorological conditions versus the worse (ie, +39% with highest temperature, +29% without rainfall, +39% with highest sunlight duration and +21% with highest length of day) and in girls on free days (ie, +26% with highest sunlight duration). This increase in MVPA contributed to a simultaneous increase in total PA when considering the same meteorological condition parameters. CONCLUSIONS: Meteorological conditions act as a determinant of PA differentially between boys and girls. PA and MVPA in boys are mainly modified by meteorological conditions on free days whereas PA and MVPA in girls are modified by sunlight duration.

Physical activity is associated with improved bone health in children with inflammatory bowel disease.

BACKGROUND & AIMS: Bone health is an important concern in patients with inflammatory bowel disease (IBD). Low bone mineral density (BMD) is a powerful predictor of fracture risk in IBD patients. Physical activity (PA) plays an important role in bone health. However, PA data for children and adolescents with IBD are scarce. The primary aim is to evaluate the relationship between PA and BMD in children with IBD. The secondary aim was to assess the relationship between PA and quality of life. METHODS: Eighty-four IBD paediatric patients (45 boys) aged 14.3 ± 2.7 years were included (disease activity: (i) remission, n = 62; (ii) mild, n = 18; (iii) severe disease, n = 1). BMD was measured using dual-energy X-ray absorptiometry and expressed as age- and sex-based Z-scores. Each patient wore a triaxial accelerometer for seven consecutive days for objective PA quantification. Quality of life was assessed using the PedsQL™ and energy intake was assessed prospectively for three days using a dietary diary. RESULTS: BMD Z-score was -0.96 ± 1.11. Only five patients (6%) fulfilled the recommendation of 60 min of daily moderate-to-vigorous PA (MVPA). The proportion of children with osteopenia and osteoporosis was 51% and 4%, respectively. After adjustment for confounders (pubertal status and body mass index), total PA and time in MVPA were positively associated with BMD (regression coefficient per one standard deviation increase in PA parameters = 0.26; P < 0.05). There was no association between time spent in MVPA and total PA, and total quality of life score. CONCLUSIONS: PA likely is associated with improved bone health in IBD children. Intervention studies investigating a causal relationship between PA and BMD in paediatric patients with IBD are warranted.

Do adolescents accurately evaluate their diet quality? The HELENA study.

BACKGROUND & AIMS: The aim of this study was to assess the diet quality awareness and associated factors in a large sample of European adolescents. METHODS: The study included 3389 healthy adolescents, aged 12.5-17.5 years, who participated in the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) Study. The adolescents' diet quality was based on repeated 24 h recalls and scored into a Diet Quality Index for Adolescents (DQI-A) considering four components: meal, equilibrium, diversity and quality. A self-rated diet quality questionnaire was administered to adolescents to assess their dietary awareness. The association of DQI-A with dietary awareness was studied using a linear mixed model including the center as the random effect and dietary awareness as the fixed effect. RESULTS: There was a positive association between DQI-A scores and diet quality perception levels (p < 0.0001). The mean DQI-A was 59.0 (SD = 14.8) in adolescents with a low dietary awareness compared with 65.4 (SD = 12.6) in adolescents with high dietary awareness (p < 0.0001). Similar results were found for all the DQI components. When analyses were stratified, we found a significant heterogeneity across the nutritional status, with no significant association between DQI-A and dietary awareness level in obese adolescents, but a positive association in overweight, normal and undernourished groups. We found also a significant heterogeneity associated with the lunch location (school or home). No other factor affected dietary awareness (gender, pubertal status and maternal educational level). CONCLUSION: European adolescents evaluate well their food quality whatever their pubertal status, gender and parental educational level, except for the obese who are not able to assess their diet quality. Improving the dietary awareness in obese adolescents might help to induce behavioral changes.

[From the influence of genes to the influence of family and urban environment on the nutritional status, activity, and physical condition of european urban adolescents]. / Le statut nutritionnel, l'activité et la condition physique des adolescents sous influence - Résultats de l'étude HELENA.

HELENA was a cross-sectional study carried out from 2006 to 2007 in more than 3500 adolescents aged from 12.5 to 17.5 years old through 10 Europeans towns from 9 countries. Its objective was to assess adolescent nutritional status including: body composition, biological markers, physical activity and fitness. This study shown the high impact of socio-economic condition, life style and personal and collective environment, dietary pattern (including breastfeeding), some genetic mutations involved in adiposity and metabolism, physical activity level and fitness on adolescent nutritional status.

Physical Activity Is Associated with Attention Capacity in Adolescents.

OBJECTIVE: To assess the relationships among physical activity, measured objectively, and attention capacity in European adolescents. STUDY DESIGN: The study included 273 adolescents, aged 12.5-17.5 years, who participated in the Healthy Lifestyle in Europe by Nutrition in Adolescence Study. Participants wore a uniaxial accelerometer for 7 days to measure physical activity. The d2 Test of Attention was administered to assess attention capacity. Multivariate analyses were used to study the association of attention capacity with each measure of physical activity. Receiver operating characteristic analysis was performed to determine thresholds that best discriminate between low and good attention capacity. RESULTS: After controlling for potential confounding variables (age, sex, body mass index, parental educational level, fat mass, aerobic fitness, and center), adolescents' attention capacity test performances were significantly and positively associated with longer time spent in moderate or moderate-to-vigorous physical activity (MVPA) in free-living conditions (P < .05). Receiver operating characteristic curve analyses revealed that the physical activity thresholds that best discriminated between low/good attention capacities were ≥41 min·day(-1) for moderate, ≥12 min·day(-1) for vigorous, and ≥58 min·day(-1) for MVPA. CONCLUSION: These findings suggest that promoting MVPA may be have a beneficial effect on attention capacity, an important component of cognition, in adolescents.

Effects of clustering of multiple lifestyle-related behaviors on blood pressure in adolescents from two observational studies.

BACKGROUD: Several lifestyle-related behaviors are associated with cardiovascular health outcomes in adolescents. To examine the associations between clustered lifestyle-related behaviors and blood pressure (BP) levels in adolescents. METHODS: Participants were recruited by multistage random cluster in two cross-sectional studies; one conducted in 2006 and 2007 in ten cities from nine European countries: Athens and Heraklion in Greece, Dortmund in Germany, Ghent in Belgium, Lille in France, Pécs in Hungary, Rome in Italy, Stockholm in Sweden, Vienna in Austria, and Zaragoza in Spain; and another conducted in 2007 one city in Brazil (Maringá/PR). Systolic BP (SBP) and diastolic BP (DBP) (outcomes) and clustered behaviors (weekly consumption of fruits and vegetables, weekly consumption of sugar-sweetened beverages, sleep duration, screen time and physical activity) were analyzed. RESULTS: The Healthy Eating cluster was negatively associated with DBP in European girls, ß=-2.46 (-4.62; -0.30), and with SBP in Brazilian boys, ß=-2.79 (-3.10; -0.15). Furthermore, the Unhealthy Eating cluster was associated with increased SBP in European girls, ß=4.54 (1.29; 7.79), and in Brazilian boys, ß=4.10 (0.80; 7.40). CONCLUSION: The Healthy Eating cluster was associated with lower blood pressure, whereas the Unhealthy Eating cluster was associated with increased SBP in adolescents.

Health inequalities in urban adolescents: role of physical activity, diet, and genetics.

OBJECTIVE: Coordinated European projects relying on standardized methods are needed to identify health inequalities across Europe. This study aimed to compare fitness, fatness, and cardiometabolic risk between urban adolescents from the south and center-north of Europe and to explore whether physical activity (PA) and other factors might explain these differences. METHODS: The Healthy Lifestyle in Europe by Nutrition in Adolescence cross-sectional project comprised 3528 adolescents from the south (4 cities) and central-north (6 cities) of Europe, 1089 of whom provided blood samples for analysis. Fitness (strength, speed-agility, and cardiorespiratory fitness), total and abdominal fatness (anthropometry and bioelectrical impedance), and cardiometabolic risk (z scores including fitness, fatness, blood lipids, insulin resistance, and blood pressure) were assessed. The analyses were adjusted for socioeconomic factors, objectively measured PA (accelerometry), total energy intake and diet quality, and genetic variants of the FTO rs9939609 polymorphism. RESULTS: Adolescents from southern Europe were less fit and fatter according to all markers (P < .001). Differences in cardiometabolic risk scores were not consistent. Adolescents from the south were less active and this would largely explain the differences observed in speed-agility and cardiorespiratory fitness. Differences in total and abdominal fatness could not be explained by PA, energy intake, diet quality, or FTO rs9939609 polymorphism. CONCLUSIONS: Fitness and fatness levels indicate that urban adolescents from the south are less healthy than those from central-northern Europe. Our data suggest that differences in PA might explain differences in important health-related fitness components, yet factors explaining the differences in fatness encountered remain unknown.

More physically active and leaner adolescents have higher energy intake.

OBJECTIVE: To test whether youths who engage in vigorous physical activity are more likely to have lean bodies while ingesting relatively large amounts of energy. For this purpose, we studied the associations of both physical activity and adiposity with energy intake in adolescents. STUDY DESIGN: The study subjects were adolescents who participated in 1 of 2 cross-sectional studies, the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study (n = 1450; mean age, 14.6 years) or the European Youth Heart Study (EYHS; n = 321; mean age, 15.6 years). Physical activity was measured by accelerometry, and energy intake was measured by 24-hour recall. In the HELENA study, body composition was assessed by 2 or more of the following methods: skinfold thickness, bioelectrical impedance analysis, plus dual-energy X-ray absorptiometry or air-displacement plethysmography in a subsample. In the EYHS, body composition was assessed by skinfold thickness. RESULTS: Fat mass was inversely associated with energy intake in both studies and using 4 different measurement methods (P ≤ .006). Overall, fat-free mass was positively associated with energy intake in both studies, yet the results were not consistent across measurement methods in the HELENA study. Vigorous physical activity in the HELENA study (P < .05) and moderate physical activity in the EYHS (P < .01) were positively associated with energy intake. Overall, results remained unchanged after adjustment for potential confounding factors, after mutual adjustment among the main exposures (physical activity and fat mass), and after the elimination of obese subjects, who might tend to underreport energy intake, from the analyses. CONCLUSION: Our data are consistent with the hypothesis that more physically active and leaner adolescents have higher energy intake than less active adolescents with larger amounts of fat mass.

Mechanical ventilatory constraints during incremental exercise in healthy and cystic fibrosis children.

AIM: To analyze breathing pattern and mechanical ventilatory constraints during incremental exercise in healthy and cystic fibrosis (CF) children. METHODS: Thirteen healthy children and 6 children with cystic fibrosis volunteered to perform an incremental test on a treadmill. Exercise tidal flow/volume loops were plotted every minute within a maximal flow/volume loop (MFVL). Expiratory flow limitation (expFL expressed in %Vt) was evaluated and end-expiratory and end-inspiratory lung volumes (EELV and EILV) were estimated from expiratory reserve volume relative to vital capacity (ERV/FVC) and from inspiratory reserve volume relative to vital capacity (IRV/FVC). RESULTS: During the incremental exercise, expFL was first observed at 40% of maximal aerobic speed in both groups. At maximal exercise, 46% of healthy children and 83% of CF children presented expFL, without significant effect of cystic fibrosis on the severity of expFL. According to the two-way ANOVA results, both groups adopted similar breathing pattern and breathing strategies as no significant effect of CF has been revealed. But, according to one-way ANOVA results, a significant increase of ERV/FVC associated with a significant decrease of IRV/FVC from resting value shave been observed in healthy children at maximal exercise, but not in CF children. DISCUSSION: The hypothesis of this study was based on the assumption that mild cystic fibrosis could induce more frequent and more severe mechanical ventilatory constraints due to pulmonary impairment and breathing pattern disturbances. But, this study did not succeed to highlight an effect of mild cystic fibrosis on the mechanical ventilatory constraints (expFL and dynamic hyperinflation) that occur during an incremental exercise. This absence of effect could be due to the absence of an impact of the disease on spirometric data, breathing pattern regulation during exercise and breathing strategy.

A favorable built environment is associated with better physical fitness in European adolescents.

OBJECTIVE: To assess the association between the built environment and physical fitness and physical activity in adolescents. METHODS: The study included 3528 adolescents, aged 12.5-17.5 years, who participated in the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA) study. The health-related physical fitness components were assessed using the physical fitness tests. Participants wore a uniaxial accelerometer (ActiGraph®) for 7 days to measure physical activity. A specific questionnaire addressing the built environment was used. Potential confounding factors including age, gender, body mass index, body composition, pubertal status, smoking, educational level of parents, and socioeconomic status were analyzed using backward stepwise linear regression analysis. RESULTS: Heavy traffic in the neighborhood was the strongest factor negatively associated with both physical fitness and physical activity (both P<0.05). Conversely, a secure bicycling or walking route from home to school was positively associated with various components of physical fitness and physical activity (P<0.01). Outdoor fields and gymnasiums near home were also associated with better physical fitness (P<0.01), but not with physical activity. CONCLUSIONS: A favorable built environment may contribute to health-related physical fitness and physical activity of adolescents and should be considered in future interventions and health promotion strategies.

Dietary and lifestyle quality indices with/without physical activity and markers of insulin resistance in European adolescents: the HELENA study.

Emerging data indicate that higher levels of insulin resistance (IR) are common among children and adolescents and are related to cardiometabolic risk; therefore, IR requires consideration early in life. In addition, there is a lack of conclusive evidence regarding the role of dietary nutrients on IR. The Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study (HELENA-CSS) was conducted in European adolescents aged 12·5­17·5 years. A total of 637 participants with valid homeostasis model assessment (HOMA) index data and who completed at least a 2 d 24 h dietary recall were included in the study (60% of the total HELENA-CSS sample). There were two dietary indices calculated, with the only difference between them being the inclusion or not of physical activity (PA). Markers of IR such as HOMA and the quantitative insulin sensitivity check index (QUICKI) were calculated. Pubertal status, BMI and cardiorespiratory fitness (CRF) were measured as potential confounders. The dietary index including PA was inversely associated with HOMA and directly with the QUICKI in females, but not in males, after adjusting for pubertal status, centre, BMI and CRF. In conclusion, the present study indicates that considering PA as part of the dietary index is of relevance as the resulted index is inversely related to IR independently of potential confounders including CRF. Overall, these findings suggest that intervention studies aimed at preventing IR in young people should focus on increasing the quality of the diet and also on including an optimal PA level in healthy adolescents.

Genetic and molecular insights into the role of PROX1 in glucose metabolism.

Genome-wide association studies have shown that the rs340874 single nucleotide polymorphism (SNP) in PROX1 is a genetic susceptibility factor for type 2 diabetes. We conducted genetic and molecular studies to better understand the role of PROX1 in type 2 diabetes. We assessed the impact of the whole common genetic variability of PROX1 (80 SNPs) on type 2 diabetes-related biochemical traits in the HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) study (n = 1,155). Three SNPs (rs340838, rs340837, and rs340836) were significantly associated with fasting plasma insulin levels (P ≤ 0.00295). We evaluated the impact of nine PROX1 SNPs (the three insulin-associated SNPs plus six SNPs in strong linkage disequilibrium) on luciferase reporter gene expression. The insulin-lowering alleles of rs340874, rs340873, and rs340835 were associated with lower luciferase activity in MIN6 and HepG2 cells (except for rs340874, which was in HepG2 cells only). Electrophoretic mobility shift assays indicated that specific nuclear protein bindings occur at the three SNPs in HepG2 cells, with allele-binding differences for rs340874. We also showed that the knockdown of Prox1 expression by small interfering RNAs in INS-1E cells resulted in a 1.7-fold reduction in glucose-stimulated insulin secretion. All together, we propose that reduced expression of PROX1 by cis-regulatory variants results in altered ß-cell insulin secretion and thereby confers susceptibility to type 2 diabetes.

Can differences in physical activity by socio-economic status in European adolescents be explained by differences in psychosocial correlates? A mediation analysis within the HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) study.

OBJECTIVE: Socio-economic status (SES) has been positively associated with physical activity (PA) levels in adolescents. In order to tackle these social inequalities, information is needed about the underlying mechanisms of this association. The present study aimed to investigate the potential mediating role of psychosocial correlates of PA on the relationship between SES and PA in European adolescents. DESIGN: Cross-sectional study testing the mediating role of psychosocial correlates in the SES-PA association using the product-of-coefficients test of MacKinnon. SETTING: Ten European cities in nine different countries, the HELENA (Healthy Lifestyle in Europe by Nutrition in Adolescence) Study. SUBJECTS: Adolescents (n 2780) aged 12·5-17·49 years self-reported on PA (moderate-to-vigorous intensity PA and total PA), SES indicators (education of the mother and Family Affluence Scale) and psychosocial correlates of PA (stage of change, attitudes, awareness, modelling, social support, self-efficacy, benefits, barriers and environmental correlates). RESULTS: SES (Family Affluence Scale) was significantly associated with moderate-to-vigorous intensity PA. According to single-mediator models, this association was significantly mediated by stage of change (t = 3·6, P ≤ 0·001), awareness (t = 2·7, 0·001 < P ≤ 0·01), modelling (t = 4·8, P ≤ 0·001), self-efficacy (t = 2·5, 0·01

Comparison of uniaxial and triaxial accelerometry in the assessment of physical activity among adolescents under free-living conditions: the HELENA study.

BACKGROUND: Different types of devices are available and the choice about which to use depends on various factors: cost, physical characteristics, performance, and the validity and intra- and interinstrument reliability. Given the large number of studies that have used uniaxial or triaxial devices, it is of interest to know whether the different devices give similar information about PA levels and patterns. The aim of this study was to compare physical activity (PA) levels and patterns obtained simultaneously by triaxial accelerometry and uniaxial accelerometry in adolescents in free-living conditions. METHODS: Sixty-two participants, aged 13-16 years, were recruited in this ancillary study, which is a part of the Healthy Lifestyle in Europe by Nutrition in Adolescence (HELENA). All participants wore a uniaxial accelerometer (ActiGraph GT1M®, Pensacola, FL) and a triaxial accelerometer (RT3®, Stayhealthy, Monrovia, CA) simultaneously for 7 days. The patterns were calculated by converting accelerometer data output as a percentage of time spent at sedentary, light, moderate, and vigorous PA per day. Analysis of output data from the two accelerometers were assessed by two different tests: Equivalence Test and Bland & Altman method. RESULTS: The concordance correlation coefficient between the data from the triaxial accelerometer and uniaxial accelerometer at each intensity level was superior to 0.95. The ANOVA test showed a significant difference for the first three lower intensities while no significant difference was found for vigorous intensity. The difference between data obtained with the triaxial accelerometer and the uniaxial monitor never exceeded 2.1% and decreased as PA level increased. The Bland & Altman method showed good agreement between data obtained between the both accelerometers (p < 0.05). CONCLUSIONS: Uniaxial and triaxial accelerometers do not differ in their measurement of PA in population studies, and either could be used in such studies.

European adolescents' level of perceived stress is inversely related to their diet quality: the Healthy Lifestyle in Europe by Nutrition in Adolescence study.

As stress is hypothesised to influence dietary behaviour, the relationship between perceived stress and diet quality in European adolescents was investigated. Within the Healthy Lifestyle in Europe by Nutrition in Adolescence study, adolescents (n 704, aged 12-17 years) from schools in five European cities (Ghent, Stockholm, Zaragoza, Athens and Vienna) completed a 2 d 24 h dietary recall assessment and an Adolescent Stress Questionnaire. Measurements and information were taken on height, weight, pubertal stage, parental education level, the level of moderate-to-vigorous physical activity (MVPA) and sleep duration. The Diet Quality Index for Adolescents (DQI-A) was calculated from the dietary data, which comprised three components reflecting dietary diversity, quality and equilibrium. Hierarchical linear models were performed to investigate the relationship between the adolescents' level of perceived stress and the DQI-A and its components, adjusting for relevant covariates (age, BMI z-score, pubertal stage and parental education). These models were additionally adjusted for MVPA or sleep duration. In both boys and girls, perceived stress was a significant independent negative predictor for their overall DQI-A. This inverse relationship was observed for all dietary components, except for dietary diversity in boys, and it was unaltered when additionally adjusted for MVPA or sleep duration. The observed inverse relationship between stress and diet quality within these European adolescents supports the hypothesis that stress influences dietary behaviour, thus emphasising the need for preventive stress-coping strategies for adolescents.

Physical activity, fitness, and serum leptin concentrations in adolescents.

OBJECTIVE: To examine the association of physical activity and fitness with leptin concentrations in European adolescents, after taking into account several potential confounders including total body fat (TBF). STUDY DESIGN: We conducted a cross-sectional study in a school setting for the Healthy Lifestyle in Europe by Nutrition in Adolescence Cross-Sectional Study. This study included 902 (509 girls) adolescents aged 12.5-17.5 years. Weight, height, and TBF (sum of 6 skinfold thickness) were measured, and fat free mass and body mass index were calculated. Physical activity was assessed by accelerometry. Physical fitness was assessed by the handgrip, standing long jump, 4 × 10-m shuttle run, and 20-m shuttle run tests. Serum fasting leptin, insulin, and glucose concentrations were measured, and homeostasis model assessment was computed. Multiple linear regression models were used. RESULTS: Vigorous physical activity and fitness tests (all P < .05) were negatively associated with leptin, independently of several confounders including TBF and homeostasis model assessment. These associations remained significant after further controlling for each other (physical activity and fitness). CONCLUSION: These results suggest that vigorous physical activity and fitness moderate the levels of leptin concentrations, regardless of relevant confounders including TBF. Intervention programs addressed to increase high intensity physical activity and fitness as well as to assess its impact on leptin concentration are required.