Abstract
Non-communicable diseases, above all cardiovascular disease (CVD), are the most common causes of morbidity and mortality in Europe. CVD has been shown to have its roots in childhood, although the clinical manifestations do not become evident until several decades later. The adolescent CVD risk profile has been shown to predict the extent of the atherosclerotic process in adulthood, even if the nature of the effects of biological and lifestyle factors, and their interactions, on the CVD risk profile in children and adolescents are largely unknown. The same holds true for the secular trends.
The overall purpose of the present research was to increase our knowledge of physical activity, fitness, blood pressure, blood lipids, insulin and glucose, and the interactions between them, in children aged 9 and 15 years.
Data collection took place during the school year 1998/1999 in central Sweden, and the 1,137 subjects constitute the Swedish part of the European Youth Heart Study. The level and pattern of physical activity were objectively assessed with a uniaxial accelerometer, and cardiorespiratory fitness was estimated by a maximal ergometer bike test.
Body composition was estimated from skinfold thicknesses, blood pressure was measured by an automatic oscillometric method, and fasting serum samples were analysed for insulin, glucose, triglycerides, total cholesterol and high density lipoprotein cholesterol.
The main outcomes in this population sample of healthy school children were: insulin was particularly influenced by body fat and total physical activity; data suggest a secular trend towards decreased cardiorespiratory fitness in 9-year-olds, but not in 15-year-olds; and a high fitness level was more important than high total physical activity level for a favourable CVD risk profile, but a gender difference was observed.
The practical implications of these findings are that fitness, and not only total physical activity, ought to be considered in longitudinal and future intervention studies, and that the gender perspective of these issues needs further attention.
