Correlates of objectively measured physical activity in 5-6-year-old preschool children.

AIM: The aim of this study was to identify gender specific physical activity correlates in Danish preschool children, using a socioecological approach. METHODS: This was a cross-sectional study conducted in Odense, Denmark. The gender specific models were based on data from 174 boys and 177 girls, 5-6 years of age and enrolled in 40 randomly selected preschools. Percentage of total daily time spent in moderate and vigorously physical activity (MVPA) was measured using ActiGraph accelerometers over 5 preschool days and 2 days off. Thirty-nine potential correlates of child MVPA across 5 domains were tested for associations with gender specific MVPA. RESULTS: The gender specific models consistently identified motor coordination and the parents' perceptions of their child's activity preferences during free play to be positively associated with MVPA. Days with rain or no preschool attendance were negatively associated with MVPA. For boys, rural area and the size of the preschool playground were positively associated with MVPA, whereas for girls, it was the age and the relative preschool indoor area. CONCLUSION: Individual and overall environmental correlates of MVPA were identified. However, most correlates were not or only weakly related to MVPA. It is possible that the interaction with peers and surrounding adults might contribute the most to preschool child MVPA.

Associations between bicycling and carotid arterial stiffness in adolescents: The European Youth Hearts Study.

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.

Musculoskeletal extremity injuries in a cohort of schoolchildren aged 6-12: a 2.5-year prospective study.

The objectives of this prospective school cohort study were to describe the epidemiology of diagnosed musculoskeletal extremity injuries and to estimate the injury incidence rates in relation to different settings, different body regions and injury types. In all, 1259 schoolchildren, aged 6-12, were surveyed weekly during 2.5 years using a new method of automated mobile phone text messaging asking questions on the presence of any musculoskeletal problems. All injuries were clinically diagnosed. Physical activity was measured from text messaging and accelerometers. A total number of 1229 injuries were diagnosed; 180 injuries in the upper extremity and 1049 in the lower extremity, with an overall rate of 1.59 injuries per 1000 physical activity units [95% confidence interval (CI) 1.50-1.68]. Upper extremities accounted for a rate of 0.23 (95% CI 0.20-0.27) and lower extremities accounted for 1.36 (95% CI 1.27-1.44). This study has added a wide overall perspective to the area concerning incidence and incidence rates of musculoskeletal extremity injuries in schoolchildren aged 6-12 years, including severe and less severe, traumatic, and overuse injuries. The understanding of injury epidemiology in children is fundamental to the acknowledgement and insurance of the appropriate prevention and treatment.

Physical activity intensity and subclinical atherosclerosis in Danish adolescents: the European Youth Heart Study.

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 < 0.05) in boys, but not in girls. No associations were observed between any of PA and IMT. Boys in the least fit quartile had significantly stiffer carotid arteries compared to the most fit quartile (difference between lowest and highest quartile ranging between 0.4 and 0.5 SD, P < 0.05). This difference in arterial stiffness between low and high quartiles was similar for moderate-to-vigorous PA (MVPA). Further adjustment for sedentary time attenuated the difference observed between quartiles MVPA slightly. Adiposity did not attenuate these differences. Our observations suggest that increasing CRF or MVPA in the least active group of the population may be beneficial for vascular health.

Hemodynamic variables during exercise in childhood and resting systolic blood pressure levels 6 years later in adolescence: the European Youth Heart Study.

The aim of this study was to analyze whether systolic blood pressure (SBP), heart rate (HR) and rate pressure product (RPP) during exercise in childhood can predict resting SBP levels in adolescence independent of resting SBP and conventional cardiovascular risk factors. We studied this in a sample of Danish children followed longitudinally for 6 years. The study comprised 226 children randomly sampled at age 9, who had their blood pressure and HR measured during ergometer exercise to exhaustion and was reassessed in adolescence. SBP and RPP during exercise in stage two of the test were positively associated with future resting SBP, independent of resting SBP in childhood (P=0.045 and P=0.013, respectively). After additional adjustment for conventional cardiovascular risk factors the associations with SBP and RPP during stage two on future resting SBP only slightly materially change, although only RPP remained significant (P=0.059 and P=0.012, respectively). No significant independent associations were observed for HR during exercise, but associations were in the same direction. Our results supports that measuring SBP and RPP, during a standard acute ergometer exercise test in children, improves the prediction of future SBP levels during rest in adolescence independent of resting SBP and conventional cardiovascular risk factors.

Secular trends in physical fitness in Danish adolescents.

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.

Linking definition of childhood and adolescent obesity to current health outcomes.

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 >or=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.

Physical fitness in relation to transport to school in adolescents: the Danish youth and sports study.

In many Western countries, there are concerns about declining levels of physical activity in school-aged children. Active transport is one way to increase physical activity in children, but few studies have evaluated whether active transport in school-aged children and adolescents has beneficial effects on fitness and, if so, whether different modes of transport affect different aspects of fitness. In this study, we examined the association of active transport with different aspects of fitness in a representative Danish sample of 545 boys and 704 girls, 15-19 years of age. Physical fitness was assessed through a number of field tests, including a maximal cycle test, dynamic and static strength in different muscle groups, muscle endurance, flexibility and agility. Transport to school was reported as the mode of transport. Almost two-thirds of the population cycled to school. Cyclists had higher aerobic power than both walkers and passive travelers (4.6-5.9%). Isometric muscle endurance (10-16%), dynamic muscle endurance in the abdominal muscles (10%) and flexibility (6%) were also higher in cyclists compared with walkers and passive travelers. Mode of travel was not related to leisure-time sports participation. Our findings suggest that commuter bicycling may be a way to improve health in adolescents.

Between- and within-day variability in physical activity and inactivity in 9- and 15-year-old European children.

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 > or =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 > or =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 > or =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.

Objectively measured habitual physical activity in 1997/1998 vs 2003/2004 in Danish children: the European Youth Heart Study.

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).

A 3-year physical activity intervention program increases the gain in bone mineral and bone width in prepubertal girls but not boys: the prospective copenhagen school child interventions study (CoSCIS).

The aim of this study was to evaluate the effect of increasing the amount of time spent in physical education classes on bone mineral accrual and gain in bone size in prepubertal Danish children. A total of 135 boys and 108 girls, aged 6-8 years, were included in a school-based curriculum intervention program where the usual time spent in physical education classes was doubled to four classes (180 min) per week. The control group comprised age-matched children (62 boys and 76 girls) recruited from a separate community who completed the usual Danish school curriculum of physical activity (90 min/week). Dual-energy X-ray absorptiometry was used to evaluate bone mineral content (BMC; g), bone mineral density (g/cm(2)), and bone width at the calcaneus and distal forearm before and after 3 years of intervention. Anthropometrics and Tanner stages were evaluated on the same occasions. General physical activity was measured with an accelerometer worn for 4 days. In girls, the intervention group had a 12.5% increase (P = 0.04) in distal forearm BMC and a 13.2% increase (P = 0.005) in distal forearm scanned area compared with girls in the control group. No differences were found between the intervention and control groups in boys. Increasing the frequency of physical education classes for prepubertal children is associated with a higher accrual of bone mineral and higher gain in bone size after 3 years in girls but not in boys.

Sources of variation in habitual physical activity of children and adolescents: the European youth heart study.

The present study examined the influence of gender, maturity state, seasonality, type of measurement day and socioeconomic status (SES) on habitual physical activity in 8-10-year-old children and 14-16-year-old adolescents (n=1318). Physical activity was assessed objectively by accelerometry. The results showed a significant effect of the type of measurement day on physical activity with a general pattern of lower activity levels in weekends compared with weekdays. Furthermore, higher physical activity levels were observed during the months of spring/summer compared with the months of autumn/winter for the 8-10-year-olds, whereas no significant effect of months was observed for the 14-16-year-olds, possibly due to exam preparations and lack of physical activity registration during the months of summer for this cohort. SES was unrelated to physical activity in the 8-10-year-olds, whereas an inverse association was observed in the 14-16-year-olds. However, a post hoc analysis provided strong evidence that this latter result was biased by the accelerometers inability to pick up bicycling activities. Finally, boys were more physically active compared with girls, and maturity state was unrelated to physical activity. The results could prove useful for working out strategies to prevent inactivity and for adjusting for temporal sources of variation in physical activity in future studies.

Tracking of objectively measured physical activity from childhood to adolescence: the European youth heart study.

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.

Independent associations of physical activity and cardiorespiratory fitness with metabolic risk factors in children: the European youth heart study.

AIMS/HYPOTHESIS: High levels of cardiorespiratory fitness (CRF) and physical activity (PA) are associated with a favourable metabolic risk profile. However, there has been no thorough exploration of the independent contributions of cardiorespiratory fitness and subcomponents of activity (total PA, time spent sedentary, and time spent in light, moderate and vigorous intensity PA) to metabolic risk factors in children and the relative importance of these factors. METHODS: We performed a population-based, cross-sectional study in 9- to 10- and 15- to 16-year-old boys and girls from three regions of Europe (n = 1709). We examined the independent associations of subcomponents of PA and CRF with metabolic risk factors (waist circumference, BP, fasting glucose, insulin, triacylglycerol and HDL-cholesterol levels). Clustered metabolic risk was expressed as a continuously distributed score calculated as the average of the standardised values of the six subcomponents. RESULTS: CRF (standardised beta = -0.09, 95% CI -0.12, -0.06), total PA (standardised beta = -0.08, 95% CI -0.10, -0.05) and all other subcomponents of PA were significantly associated with clustered metabolic risk. After excluding waist circumference from the summary score and further adjustment for waist circumference as a confounding factor, the magnitude of the association between CRF and clustered metabolic risk was attenuated (standardised beta = -0.05, 95% CI -0.08, -0.02), whereas the association with total PA was unchanged (standardised beta = -0.08 95% CI -0.10, -0.05). CONCLUSIONS/INTERPRETATION: PA and CRF are separately and independently associated with individual and clustered metabolic risk factors in children. The association between CRF and clustered risk is partly mediated or confounded by adiposity, whereas the association between activity and clustered risk is independent of adiposity. Our results suggest that fitness and activity affect metabolic risk through different pathways.

Peripheral bone mineral density and different intensities of physical activity in children 6-8 years old: the Copenhagen School Child Intervention study.

This study aimed to evaluate the association between objectively measured habitual physical activity and calcaneal and forearm bone mineral density (BMD, g/cm(2)), one mechanically more loaded and one less loaded skeletal region, in children aged 6-8 years. BMD was measured in 297 boys and 265 girls by peripheral dual-energy X-ray absorptiometry in the forearm and calcaneus. An accelerometer registered the level of physical activity during 4 days (2 weekdays and the weekend). Weight, height, and skinfold thickness were measured. In order to establish thresholds (count . min(-1)) for bone-stimulating physical activity, we evaluated different definitions of vigorous physical activity. The boys had 3.2% higher distal forearm bone mineral content (BMC, P < 0.001) and 4.5% higher distal forearm BMD (P < 0.001) than the girls. They also carried out 9.7% more daily physical activity and spent 14.6-19.0% more time in vigorous physical activity (all P < 0.05) compared to the girls. In contrast, the girls had 3.8% higher calcaneal BMC (P < 0.01) and 2.5% higher calcaneal BMD (P < 0.05) than the boys. Both calcaneal and forearm BMD were significantly related to total time of daily physical activity as well as with intense physical activity above all the chosen cut-off points (all P < 0.05). The beta value for mean count . min(-1) physical activity was significantly lower than that for all the chosen cut-off points of vigorous activity both for calcaneal and distal forearm BMD. This study suggests that both habitual daily physical activity and amount of vigorous physical activity in children aged 6-8 years are associated with appendicular BMD.

Secular trends in cardiorespiratory fitness and body mass index in Danish children: The European Youth Heart Study.

AIM: To examine the secular trends in cardiorespiratory fitness (CF) and body fatness in Danish children. Trends were analyzed overall and across socioeconomic status (SES). METHODS: Two cross-sectional studies conducted on 589 and 458 third-grade Danish children in 1997-1998 and 2003-2004, respectively. CF was determined by a maximal cycle-ergometer test. The lowest sex-specific quartile of CF in the study from 1997 to 1998 was used as a cut-point for low CF. Body mass index (BMI) cut-points were used to describe overweight, and SES was divided into two groups according to parents' occupation. RESULTS: This study showed a secular decline in CF in girls overall. Increased CF, BMI, and prevalence of overweight were observed in boys with high SES, in boys with low SES, and in girls with low SES, respectively. However, after additional Bonferroni's correction, none of the statistical analyses performed across socioeconomic gradients reached significant P-values. CONCLUSION: CF declined in girls overall. Although not statistically significant after additional Bonferroni's correction, results in general showed less favorable trends in low SES children. Thus, trying to describe secular trends in CF and body fatness overall without any regard to SES might disguise social-caused differences. However, further studies are needed in order to verify this hypothesis.

Sex differences in bone size and bone mineral density exist before puberty. The Copenhagen School Child Intervention Study (CoSCIS).

BACKGROUND: The aim of this study was to provide normative data of bone mineral density (BMD; g/cm(2)) of the forearm and the calcaneus, evaluated by peripheral dual X ray absorbtiometry (DXA), in children aged 6 to 7 years of age and to evaluate the association with anthropometrics and sex. MATERIAL AND METHODS: 368 boys and 326 girls with a mean age of 6.7 +/- 0.4 years participated. BMD was measured by DXA in the forearms and the os calcanei, with average values presented in this report. Measurements of weight, height, skinfolds, the width of distal radius and ulna, and the femur condyles were collected and body composition estimated from skinfolds measurements. RESULTS: There was no difference in calcaneus BMD when comparing boys and girls, whereas the boys had 4.5% (0.013 g/cm(2)) higher forearm BMD than the girls (P < 0.001). Calcaneal BMD (mean 0.318 g/cm(2)) was 11% higher than forearm BMD (mean 0.283 g/cm(2)). Linear relationship was found between calcaneus BMD and weight (partial r = 0.50), Fat free mass (FFM) (partial r = 0.50), Fat mass (FM) (partial r = 0.45), % body fat (partial r = 0.29) and knee width (partial r = 0.46), all P < 0.000 respectively. Adjusted for weight the relationship between calcaneus BMD and FFM, FM, %body fat and knee width disappeared. There were significant relationships between the forearm BMD and weight (partial r = 0.37), FFM (partial r = 0.39), FM (partial r = 0.28), %body fat (partial r = 0.14) and wrist width (partial r = 0.24), all P < 0.000 respectively. Adjusted for body weight, the relationship remained between forearm BMD and FFM (r = 0.10), FM (R = -0.10) and % body fat (r = -0.12), all P < 0.000 respectively. Children measured in the spring had 3.5% (P < 0.01) higher calcaneus BMD than children measured in the winter. CONCLUSION: Seven year old boys have higher BMD in the forearm but not in the calcaneus in comparison with girls of a similar age. Body weight is the best predictor of calcaneus BMD, accounting for 25% of the variance whereas body weight and FFM are the best predictors of forearm BMD, each accounting for 17% of the variance, respectively.

The role of calcium oxalate crystal deposition in cerebral vessels during ethylene glycol poisoning.

Ethylene glycol (EG) poisoning can lead to serious morbidity or death, which occurs following conversion of ethylene glycol to toxic metabolites. These metabolites affect multiple organ/systems leading to metabolic acidosis, cardiopulmonary depression, acute renal failure and central nervous system deficits. Treatment consists of correcting metabolic acidosis with bicarbonate administration, dialysis to remove toxic metabolites and administration of fomepizole or ethanol to prevent conversion of EG to toxic intermediates. Occasionally in the literature, fatal cases of EG poisoning have been described in which calcium oxalate crystal deposition has occurred in the walls of CNS vessels, sometimes with associated neuropathy. We describe a case of fatal EG poisoning in which the development of rapid cerebral edema was documented by CT scan and was accompanied by definitive evidence of birefringent crystals within walls of CNS blood vessels, with associated inflammation and edema. This case and others in the literature suggest that cerebral edema, and perhaps injury to other organs, could result from oxalate crystal deposition in small blood vessels in the brain and other organs.

Graded associations between cardiorespiratory fitness, fatness, and blood pressure in children and adolescents.

OBJECTIVE: To measure the graded relation between cardiorespiratory fitness and sum of skinfolds, waist circumference, and blood pressure in children and adolescents participating in the European youth heart study. METHODS: The participants were 4072 children and adolescents (aged 9 and 15) from Denmark, Portugal, Estonia, and Norway. Cardiorespiratory fitness was indirectly determined using a maximal ergometer cycle test. The sum of four skinfolds, waist circumference, and blood pressure were assessed with a standardised protocol. Linear regression analysis was used to test the graded relation between cardiorespiratory fitness and the dependent variables adjusted for pubertal stage, sex, and country. RESULTS: A significant curvilinear graded relation was found between cardiorespiratory fitness and waist circumference and sum of skinfolds (partial r2 for cardiorespiratory fitness was 0.09-0.26 for the different sexes and age groups). Systolic and diastolic blood pressure also showed a curvilinear relation with cardiorespiratory fitness, and fitness explained 2% of the variance in systolic blood pressure. The difference in systolic blood pressure between the least and most fit was 6 mm Hg. CONCLUSION: A curvilinear graded relation was found between cardiorespiratory fitness and waist circumference, sum of skinfolds, and systolic blood pressure. The greatest difference in these health variables was observed between low and moderate fitness levels.

Mini review: physical activity and fitness and its relations to cardiovascular disease risk factors in children.

OBJECTIVES: This paper aim to review the newest literature linking physical inactivity and low fitness to metabolic disorders including cardiovascular disease (CVD) risk factors and obesity. METHODS: There is a rationale for early prevention of CVD if (a) children have a risk factor profile, where risk for future disease is increased, (b) physical activity and CVD risk factors track into adulthood, and (c) increased physical activity can improve the risk factor profile. We reviewed the evidence for a progressive evolution of atherosclerosis starting in childhood, and also that physical activity decreases the rate of the process through several mechanisms. Among the central mechanisms mediating the effect of physical activity are (a) increased insulin sensitivity, (b) a non-insulin-dependent glucose uptake, which causes lower insulin release, (c) an improved ratio between HDL and LDL cholesterol because of increased activity of lipoprotein lipase, and d) improved function of other metabolic hormones and enzymes for fat metabolism. RESULTS: The association between CVD risk factors and physical activity/fitness is weak, when risk factors are analysed isolated. In the normal healthy population of children, studies have shown that risk factors cluster and this clustering is strongly related to low physical activity or fitness. In European children it has been found that as many as 15% of 9-y-old children has clustered risk. Most of the overweight and obese children are among these, but many of the children are lean inactive children, who may later become overweight because of insulin resistance. CONCLUSION: It can be concluded that there is a large potential for primary prevention of CVD in European children, and lifestyle changes including increased physical activity as one of the key actions should be initiated.