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UBC Theses and Dissertations

Effects of a school-based physical activity model on cardiovascular disease risk factors in children Reed, Katharine


Background: The prevalence of CVD risk factors in children is high. Physical activity is linked with cardiovascular health but 50% of children are not considered active enough to maintain good health. Objectives: The primary objectives were to; i) evaluate the prevalence of established and novel CVD risk factors in elementary school children, and ii) assess the effect of a school-based physical activity model on selected GVD risk factors. Research design: A 16-month cluster-randomized controlled school-based intervention with the research questions addressed in 6 sub-studies. Sub-studies 1- 4 are cross sectional analyses of baseline data. Substudies 5 and 6 are results from 1-school year of the randomized controlled trial. Methods: Ten schools were randomized to intervention (INT) or control (CON) groups. Children (n=268, aged 9-11 years) from 8 schools took part in Healthy Hearts measurements. The trial aimed to provide children with 150 minutes of moderate-to-vigorous physical activity per week. Anthropometry, physical activity, cardiovascular fitness, blood pressure, arterial compliance, heart rate variability and serum factors were assessed at baseline and final. Results: Study 1:1 developed a Healthy Heart Score to assess potential CVD risk. Girls had a more favourable Healthy Heart Score than boys. 47% of girls and 68% of boys had at least one CVD risk factor. Study 2: Fitness level of Canadian children at the 50t h percentile in 2004 was equivalent to the fitness of Canadian children at the 19th percentile in 1981. Study 3: A significant relationship exists between cardiovascular fitness and arterial compliance in boys and girls. Study 4: Racial differences in heart rate variability exist between Asian- and Caucasian-Canadian children. Sub-study 5: INT children had a 20% greater increase in fitness compared with CON children. Children deemed at higher risk for CVD showed large improvements in blood pressure and serum factors. Sub-study 6: INT boys demonstrated a 25% greater improvement in large artery compliance than CON boys. Conclusions: There was a relatively high prevalence of CVD risk factors in this cohort of children. Action Schools! BC offers promise as a simple, inexpensive strategy for enhancing cardiovascular health in similar children.

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