BACKGROUND:

It is well documented that the roots of cardiovascular diseases (CVD) are evident in childhood, and elevated levels of serum lipids, blood pressure and body fat are common in childhood. These risk factors are, in turn, related to childhood dietary and physical activity habits. To understand the early development of CVD, it is therefore important to study factors that influence diet and physical activity behaviors in children.

Most studies concerned with the determinants of diet and physical activity in children are cross-sectional, limiting their utility for improving understanding of the development of these key health behaviors.

The study allowed prospective analyses of the behaviors over a significant portion of the prepubertal age range. Knowledge of the determinants, stability, and relationships of childhood dietary and physical activity behaviors to physiologic risk variables could be useful for setting priorities and designing public health interventions for the next generations of youth.

The major contribution of this San Diego SCAN study was in the longitudinal analysis of dietary and physical activity behaviors in children. The follow-up assessment of the 10-to 11-year-old cohort and their mothers produced data that substantially improved understanding of the determinants and tracking of children's dietary and physical activity behaviors, as well as their relations to CVD risk factors.

DESIGN NARRATIVE:

Selection of subjects studied was based on social learning/cognitive theory, which states that behaviors are a function of personal and environmental factors. The specific aims of the study were as follows: 1) To study the determinants of physical activity and dietary intake of fat, sodium, and calories, and changes in these behaviors in children from ages 4 to 10-11. 2) To determine the relationships between diet and physical activity practices and physiologic indicators of risk, such as blood pressure, adiposity, body mass, and serum lipoproteins at ages 4 to 10-11. 3) To describe the time trends and the degree of tracking of physical activity habits and nutritional intake of fat, sodium, and calories in children from ages 4 to 10-11. The study was renewed in 1999.