Maarike Harro

Physical activity and clustered cardiovascular risk in children: a cross-sectional study (The European Youth Heart Study)

BACKGROUND Atherosclerosis develops from early childhood; physical activity could positively affect this process. This studys aim was to assess the associations of objectively measured physical activity with clustering of cardiovascular disease risk factors in children and derive guidelines on the basis of this analysis. METHODS We did a cross-sectional study of 1732 randomly selected 9-year-old and 15-year-old school children from Denmark, Estonia, and Portugal. Risk factors included in the composite risk factor score (mean of Z scores) were systolic blood pressure, triglyceride, total cholesterol/HDL ratio, insulin resistance, sum of four skinfolds, and aerobic fitness. Individuals with a risk score above 1 SD of the composite variable were defined as being at risk. Physical activity was assessed by accelerometry. FINDINGS Odds ratios for having clustered risk for ascending quintiles of physical activity (counts per min; cpm) were 3.29 (95% CI 1.96-5.52), 3.13 (1.87-5.25), 2.51 (1.47-4.26), and 2.03 (1.18-3.50), respectively, compared with the most active quintile. The first to the third quintile of physical activity had a raised risk in all analyses. The mean time spent above 2000 cpm in the fourth quintile was 116 min per day in 9-year-old and 88 min per day in 15-year-old children. INTERPRETATION Physical activity levels should be higher than the current international guidelines of at least 1 h per day of physical activity of at least moderate intensity to prevent clustering of cardiovascular disease risk factors.

Physical activity levels and patterns of 9- and 15-yr-old European children.

PURPOSE The purpose of this study was to assess physical activity levels and patterns from children participating in the European Youth Heart Study (EYHS). Very limited physical activity data exist that have been collected from representative samples of children and even fewer data collected where physical activity has been measured using objective methods. METHODS Subjects were 2185 children aged 9 and 15 yr from Denmark, Portugal, Estonia, and Norway. Physical activity data were obtained using MTI (formerly CSA) accelerometers. The primary outcome variable was established as the childs activity level (accelerometer counts per minute). Children wore the accelerometer for 3 or 4 d, which included at least 1 weekend day. RESULTS Boys were more active than girls at age 9 (784 +/- 282 vs 649 +/- 204 counts.min-1) and 15 yr (615 +/- 228 vs 491 +/- 163 counts.min-1). With respect to time engaged in moderate-intensity activity, gender differences were apparent at age 9 (192 +/- 66 vs 160 +/- 54 min.d-1) and age 15 (99 +/- 45 vs 73 +/- 32 min.d-1). At age 9, the great majority of boys and girls achieved current health-related physical activity recommendations (97.4% and 97.6%, respectively). At age 15, fewer children achieved the guidelines and gender differences were apparent (boys 81.9% vs girls 62.0%). CONCLUSIONS Accelerometers are a feasible and accurate instrument for use in large epidemiological studies of childrens activity. Boys tend to be more active than girls, and there is a marked reduction in activity over the adolescent years. The great majority of younger children achieve current physical activity recommendations, whereas fewer older children do so-especially older girls.

TV viewing and physical activity are independently associated with metabolic risk in children: the European Youth Heart Study.

Background TV viewing has been linked to metabolic-risk factors in youth. However, it is unclear whether this association is independent of physical activity (PA) and obesity. Methods and Findings We did a population-based, cross-sectional study in 9- to 10-y-old and 15- to 16-y-old boys and girls from three regions in Europe (n = 1,921). We examined the independent associations between TV viewing, PA measured by accelerometry, and metabolic-risk factors (body fatness, blood pressure, fasting triglycerides, inverted high-density lipoprotein (HDL) cholesterol, glucose, and insulin levels). Clustered metabolic risk was expressed as a continuously distributed score calculated as the average of the standardized values of the six subcomponents. There was a positive association between TV viewing and adiposity (p = 0.021). However, after adjustment for PA, gender, age group, study location, sexual maturity, smoking status, birth weight, and parental socio-economic status, the association of TV viewing with clustered metabolic risk was no longer significant (p = 0.053). PA was independently and inversely associated with systolic and diastolic blood pressure, fasting glucose, insulin (all p < 0.01), and triglycerides (p = 0.02). PA was also significantly and inversely associated with the clustered risk score (p < 0.0001), independently of obesity and other confounding factors. Conclusions TV viewing and PA may be separate entities and differently associated with adiposity and metabolic risk. The association between TV viewing and clustered metabolic risk is mediated by adiposity, whereas PA is associated with individual and clustered metabolic-risk indicators independently of obesity. Thus, preventive action against metabolic risk in children may need to target TV viewing and PA separately.

Low cardiorespiratory fitness is a strong predictor for clustering of cardiovascular disease risk factors in children independent of country, age and sex.

Background and design Few studies have investigated the association between maximal cardiorespiratory capacity (fitness) and the clustered cardiovascular disease (CVD) risk in children and youth from culturally diverse countries. This cross-sectional study examined the association between fitness and clustered CVD risk in children and adolescents from three European countries. Methods Participants were 2845 randomly selected school children aged 9 or 15 years from Portugal (n = 944), Denmark (n = 849) and Estonia (n = 1052). Cardiorespiratory fitness was determined during a maximal test on a cycle ergometer. CVD risk factors selected to assess the degree of clustering were the total cholesterol/high-density lipoprotein cholesterol ratio, plasma triglycerides, insulin resistance (homeostasis model assessment), sum of four skinfolds, and systolic blood pressure. Results There was a strong association between cardiorespiratory fitness and the clustering of CVD risk factors. The odds ratios for clustering in each quartile of fitness, using the quartile with the highest fitness as reference, were 13.0 [95% confidence interval (CI) 8.8-19.1]; 4.8 (95% CI 3.2-7.1) and 2.5 (95% CI 1.6-3.8), respectively, after adjusting for country, age, sex, socio-economic status, pubertal stage, family history of CVD and diabetes. In stratified analyses by age group, sex and country, similar strong patterns were observed. Conclusion Low cardiorespiratory fitness is strongly associated with the clustering of CVD risk factors in children independent of country, age and sex.

Cardiorespiratory fitness relates more strongly than physical activity to cardiovascular disease risk factors in healthy children and adolescents: the European Youth Heart Study:

Background Physical activity and cardiorespiratory fitness are closely related to health variables in adults, especially those considered to be among risk factors for cardiovascular diseases. The possible tracking of cardiovascular disease risk factors from childhood to adulthood makes it important to increase our understanding of the complex relationships between physical activity, cardiorespiratory fitness and cardiovascular risk factors early in life. Design A cross-sectional, school-based study on healthy children and adolescents, aged 9-10 years (295 girls, 295 boys) and 15-16 years (302 girls, 233 boys) was performed during a school year in Sweden and Estonia, as part of the European Youth Heart Study. Methods Total physical activity, and minutes spent in inactivity and activity of moderate or higher intensity were measured by accelerometry. A maximal ergometer bike test was used for estimation of cardiorespiratory fitness. The risk factors included blood pressure and fasting blood levels of insulin, glucose, triglycerides, total cholesterol and high-density lipoprotein cholesterol. Results Canonical correlations between physical activity and cardiorespiratory fitness versus cardiovascular disease risk factors showed significant associations in both age and sex groups (r c=0.46-0.61, P < 0.0001). The cardiorespiratory fitness was found to be the strongest contributor to these relationships. In girls high values of the physical activity variables were also associated with a favourable cardiovascular profile. Conclusions Cardiorespiratory fitness relates more strongly to cardiovascular risk factors than components of objectively measured physical activity in children and adolescents. Physical activity becomes more important in the 15-year-old adolescents, indicating that these modifiable lifestyle factors increase in importance with age.

Platelet MAO activity and the 5-HTT gene promoter polymorphism are associated with impulsivity and cognitive style in visual information processing.

RationaleLow capacity of the central serotonergic system has been associated with impulsive behaviour. Both low platelet monoamine oxidase (MAO) activity and the short (S) allele of the serotonin transporter gene promoter region polymorphism (5-HTTLPR) are proposed to be markers of less efficient serotonergic functioning.ObjectivesThe effect of the two markers for serotonin system efficiency on performance in a visual comparison task (VCT) and self-reported impulsiveness (Barratt Impulsiveness Scale, BIS-11) were investigated in healthy adolescents participating in the Estonian Children Personality Behaviour and Health Study. Possible confounding effect of general cognitive abilities on the performance in VCT was controlled for.ResultsLow platelet MAO activity and carrying of the S allele of 5-HTTLPR were both associated with higher error-rate and more impulsive performance in VCT. Platelet MAO activity and 5-HTTLPR S allele had a significant interactive effect on self-reported impulsivity (BIS-11). The effect of platelet MAO activity on both self-reported and performance impulsivity was significant only in the S allele carriers. The effect of 5-HTTLPR S allele on impulsive performance remained significant after controlling for general cognitive abilities.ConclusionsThe two markers of lower serotonergic capacity, 5-HTTLPR S allele and low platelet MAO activity, have a similar and partly synergistic influence on self-reported as well as performance measures of impulsivity.

Platelet monoamine oxidase in healthy 9- and 15-years old children: the effect of gender, smoking and puberty.

1. The effect of gender, smoking and pubertal development on platelet monoamine oxidase (MAO) activity was described in a randomly selected, large sample of 9- and 15-years old healthy children. 2. Platelet MAO activity was measured in 1129 children by a radioenzymatic method with beta-phenylethylamine as the substrate. Smoking habits were reported in an anonymous questionnaire. Pubertal status was assessed visually using Tanners stages. 3. Boys, younger children and smokers had significantly lower platelet MAO activity than girls, older children and non-smokers, respectively. Girls in Tanners stage V for breast and pubic hair development had significantly lower MAO than girls in stage IV. 4. Differences in gender, age, pubertal status and smoking habits must be taken into account if the relationship between platelet MAO activity, personality and psychiatric disorders is studied in children.

Validation of a Questionnaire to Assess Physical Activity of Children Ages 4–8 Years

Three physical activity questionnaires were validated against heart rate (HR) monitoring and motion accelerometer data. All three methods were carried out simultaneously on 62 children ages 4-8 years on 4 consecutive days. The questionnaires were filled in by the childrens parents and teachers. The reported time of physical activity with moderate to vigorous intensity, expected to increase HR above 140 beats per minute (bpm), correlated with the time of HR > or = 140 bpm and > or = 150 bpm (r = .40, p < .01) and with the accelerometer score (r = .53, p < .0001). Correlation between the HR > or = 140 bpm and accelerometer score was r = .45, p < .001, and between the HR > or = 150 bpm and accelerometer score, it was r = .41, p < .01.

Cardiorespiratory fitness is associated with features of metabolic risk factors in children. Should cardiorespiratory fitness be assessed in a European health monitoring system? The European Youth Heart Study

The question as to whether fitness should be assessed in a European health monitoring system, perhaps from the early stages of life onwards, remains to be answered. We aimed to examine the associations between cardiorespiratory fitness and metabolic risk factors in children. A total of 873 healthy children from Sweden and Estonia aged 9–10 years (444 girls and 429 boys) were randomly selected. A maximal ergometer bike test was used to estimate cardiorespiratory fitness. Additional cardiovascular risk factors were assessed. Significant differences among cardiorespiratory fitness quartiles for the sum of five skinfolds, insulin resistance, triglycerides, and total cholesterol (TC) and high-density lipoprotein cholesterol (HDLc) ratio were shown in girls whereas in boys, the sum of five skinfolds and insulin resistance were significantly different. The lowest sum of five skinfolds and insulin resistance was shown in the highest cardiorespiratory fitness quartile in girls and boys, and the lowest values of triglyceride and TC/HDLc values in the highest cardiorespiratory fitness quartile was observed only in girls. Cardiorespiratory fitness was negatively associated with a clustering of metabolic risk factors in girls and boys. The results add supportive evidence to the body of knowledge suggesting that cardiorespiratory fitness in children is an important health marker and thus should be considered to be included in a pan-European health monitoring system.

Association of socioeconomic position with insulin resistance among children from Denmark, Estonia, and Portugal: cross sectional study

Abstract Objectives To examine the association between socioeconomic position and insulin resistance in children from three countries in northern Europe (Denmark), eastern Europe (Estonia), and southern Europe (Portugal) that have different physical, economic, and cultural environments. Design Cross sectional study. Participants 3189 randomly selected schoolchildren aged 9 and 15 years from Denmark (n = 933), Estonia (n = 1103), and Portugal (n = 1153). Main outcome measure Insulin resistance (homoeostasis model assessment). Results Family income and parental education were inversely associated with insulin resistance in Danish children but were positively associated with insulin resistance in Estonian and Portuguese children. Among Danish children, insulin resistance was 24% lower (95% confidence interval −38% to −10%) in those whose fathers had the most education compared with those with the least education. The equivalent results were 15% (2% to 28%) higher for Estonia and 19% (2% to 36%) higher for Portugal. These associations remained after adjustment for a range of covariates: −20% (−36% to −5%) for Denmark, 10% (−4% to 24%) for Estonia, and 18% (−1% to 31%) for Portugal. Strong statistical evidence supported differences between the associations in Denmark and those in the other two countries in both unadjusted and adjusted models (all P < 0.03). Conclusions Among Danish children, those with the most educated and highest earning parents had least insulin resistance, whereas the opposite was true for children from Estonia and Portugal.