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 r(2) 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.