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Udgivelsesdato: April Objective. To evaluate the ability of body mass index (BMI) and fat location indices to predict clustering of risk factors for cardiovascular and metabolic disorders in children and adolescents. Methods. A total of 2 835 children in the 3(rd) (8.2-11.3 years) and 9(th) (14-17.3 years) grade were randomly selected from Denmark, Estonia and Portugal. BMI, waist-circumference (WC) and waist-to-height ratio (WHt) were evaluated. Children were considered to have clustering of risk factors if >/=3 risk factors were present: high levels of total cholesterol, triglyceride, glucose, insulin, blood pressure and low levels of aerobic fitness and HDL-C. The diagnostic accuracy for detecting children at risk was evaluated through receiver operating characteristics analyses, performed separately for boys and girls in the four age groups: 8.2-9.5; 9.5-11.3; 14.0-15.5 and 15.5-17.3 years. Cut-offs producing equal sensitivity and specificity and minimizing misclassifications were derived. Children were classified as overweight and obese based on BMI cut-offs producing equal sensitivity and specificity and minimizing misclassifications, respectively. Results. The diagnostic accuracy for identifying children at risk, measured by the area under the curve (AUC), of all anthropometric indices were significantly higher than what would be expected by chance (AUC >0.5). BMI cut-offs for overweight had similar sensitivity (58.8% to 75%) and specificity (60% to 71.2%) values, whereas specificity (94.4% to 99.7%) was markedly higher than sensitivity (9.3% to 52.6%) for obesity cut-offs. Conclusion. BMI, WC and WHt can be used to identify children and adolescents aged 8.2-17.3 years with a clustering of cardiovascular risk factors.

The aim of the study was to investigate the associations between bicycling and carotid arterial stiffness, independent of objectively measured moderate-and-vigorous physical activity. This cross-sectional study included 375 adolescents (age 15.7 ± 0.4 years) from the Danish site of the European Youth Heart Study. Total frequency of bicycle usage was assessed by self-report, and carotid arterial stiffness was assessed using B-mode ultrasound. After adjusting for pubertal status, body height, and objectively measured physical activity and other personal lifestyle and demographic factors, boys using their bicycle every day of the week displayed a higher carotid arterial compliance {standard beta 0.47 [95% confidence interval (CI) 0.07-0.87]} and distension [standard beta 0.38 (95% CI -0.04 to 0.81)]. Boys using their bicycle every day of the week furthermore displayed a lower Young's elastic modulus [standard beta -0.48 (95% CI -0.91 to -0.06)]. Similar trends were observed when investigating the association between commuter bicycling and carotid arterial stiffness. These associations were not observed in girls. Our observations suggest that increasing bicycling in adolescence may be beneficial to carotid arterial health among boys.

The aim was to investigate the associations between physical activity (PA), cardiorespiratory fitness (CRF) and intima media thickness (IMT) or stiffness. This was a population-based cross-sectional study (n = 336) of Danish adolescents [mean age (standard deviation, SD): 15.6 (0.4) years]. PA intensity was assessed objectively (ActiGraph model GT3X) and CRF using a progressive maximal bicycle test. Carotid IMT and arterial stiffness were assessed using B-mode ultrasound. In a multivariate analysis (adjusted for pubertal development and smoking status), CRF was inversely associated with measures of carotid stiffness (standard beta: -0.20 to -0.15, P

We have measured the capacity of the sodium-potassium pump, as assessed by 86rubidium uptake and the number of [3H]-ouabain binding sites on white blood cells, in children aged 9-11 years, partly cross-sectionally and partly longitudinally after a physical training programme. Children from a hypertensive subgroup comprising the upper 5% of the blood pressure distribution and children from a randomly selected normotensive subgroup were eligible for the study. In the cross-sectional study 40 children from the hypertensive subgroup and 40 children from the normotensive subgroup were evaluated. A significant increase in 86rubidium uptake was present in boys as compared to girls. After adjustment for differences in sexual maturation the observed significant difference disappeared. Important correlates of pump activity were height, plasma glucose, and physical fitness. In the training study 10 boys from the hypertensive subgroup and 10 boys from the normotensive subgroup were also evaluated after eight months of physical training. A significant fall in 86rubidium uptake was observed. No control group was examined and probably the changes reflect some effects of sexual maturation on cation handling of cells. These results indicate a significant effect of sexual maturation in capacity of sodium-potassium pump in children.

Published online: 4 OCT 2009 It is important to monitor changes over time in aerobic fitness and obesity in order to target interventions when health deteriorates. We analyzed data from three population studies of adolescents carried out in 1983, 1997, and 2003. Participants were 1050 adolescents from the whole country of Denmark in 1983, 410 in 1997, and 418 in 2003, the two latter cohorts from the City of Odense. VO(2max) was estimated from maximal power output (MPO) in a cycle test with progressively increasing workload. Estimated VO(2max) for boys and girls was 52 and 41 mL/min/kg, respectively, both in 1983, 1997, and 2003 with no difference between the three cohorts. However, body mass index (BMI) increased 10% in the upper decentile of the distribution since 1983. MPO decreased over time, but validation studies showed that this was not due to decreased VO(2max). The cohort from 1983 was tested twice by school teachers and experienced scientists, and the scientists found higher MPO than school teachers in the same subjects, which emphasize the importance of good validation studies.

Udgivelsesdato: 17. februar Based on two cross-sectional studies conducted in 8-10-year-old third-grade children living in the municipality of Odense, potential differences were examined in the level of habitual physical activity (HPA) in Danish children between 1997/1998 and 2003/2004. HPA was assessed objectively by accelerometry. Primarily, overall differences were analyzed as gender and day type specific (i.e. Mon-Thu vs Fri-Sun) levels in HPA. Secondarily, differences were analyzed across socioeconomic gradients defined according to parents' occupation. Data were expressed as total counts per registered time. During the period 1997/1998-2003/2004, no significant differences were observed in the level of HPA during Mon-Thu or Fri-Sun or across socioeconomic gradients. Post hoc analyses indicated a slightly more favorable ratio between the percentages of time spent in light and moderate intensity levels during Mon-Thu in 2003/2004 when compared with 1997/1998. Gender differences in the level of HPA were found to be more distinct during Mon-Thu than during Fri-Sun. This study does not support the idea that Danish children are becoming less physically active. However, a limited statistical power should be considered when interpreting differences across socioeconomic gradients. Boys were found to be more physically active than girls, especially during the weekdays (Friday not included).

Udgivelsesdato: 1. februar To examine differences in levels of physical activity (PA), time spent at moderate-to-vigorous intensity PA (MVPA) and time spent sedentary between and within days in children from four European countries, 1954 9 - and 15-year-olds were included. PA was measured during 2 weekdays and 2 weekend days using the manufacturing technology-incorporated (MTI) accelerometer. Average count per minute, time spent sedentary, time spent at MVPA and the proportion of children accumulating >/=60 min of MVPA were calculated. Data were compared between weekdays and weekend days and between school time and leisure-time. Although not entirely consistent across countries, overall PA, time spent sedentary and the proportion of children accumulating >/=60 min of MVPA were higher during weekdays compared with weekend days. Differences in overall PA between school time and leisure-time were highly inconsistent between countries. Few children (4-31%) accumulated >/=60 min of MVPA either during school time or during leisure-time. Differences in activity patterns between weekdays and weekend days are explained by less accumulated time in MVPA during weekend days. Weekend days and leisure-time during weekdays seem appropriate targets when promoting PA in order to increase the proportion of children achieving current recommendations on health-enhancing PA.

Udgivelsesdato: April A number of studies have investigated tracking of physical activity from childhood to adolescence and, in general, these studies have been based on methods with some degree of subjectivity (e.g., questionnaires). The aim of the present study was to evaluate tracking of physical activity from childhood to adolescence using accelerometry, taking into account major sources of variation in physical activity. Both a crude and an adjusted model was fitted, and, in the adjusted model, analyses were corrected for seasonal variation, within-week variation, activity registration during night time sleep, within instrumental measurement error, and day-to-day variation in physical activity. In all, 208 subjects were included in the crude analyses. Stability coefficients estimated from the crude model were low (i.e., 0.18 and 0.19 for boys and girls, respectively) and only borderline significant. However, in the adjusted model highly significant stability coefficients of 0.53 and 0.48 for boys and girls, respectively, were observed. It was concluded that physical activity behavior tends to track moderately from childhood to adolescence.