Physical activity and risk of overweight in children 6 to 8 years of age: A study of physical activity of children in the infant growth study

Background. Concern exists with the decrease in physical activity levels in children, and concurrent increase in childhood overweight. Little is known of the degree to which decreases in physical activity intensity levels can promote excess adiposity. Additionally, little is known regarding the relationship of risk of overweight and physical activity on increase in body mass index (BMI or kg/m2).; Objective. This study examined: (1) the impact of physical activity intensity and overweight risk at age 7 on BMI at age 8, (2) the impact of physical activity and overweight risk on fat mass (FM) and fat free mass (FFM), and (3) correlations between measured physical activity and reported physical inactivity on the Child Activity Questionnaire.; Design. A cross-sectional study. Subjects included a total of 55 Caucasian children, 30 at low risk of overweight based on maternal BMI (maternal BMI = 19.5 +/- 1.1 kg/m2) and 30 at high risk based on maternal BMI (BMI = 30.2 +/- 4.2 kg/m2). Objective measurement of physical activity intensity over 7 days was collected by TriTrac R3D accelerometry. Parents reported child's typical physical inactivity at age 7 by the Child Activity Questionnaire. BMI was calculated from measured height and weight at ages 7 and 8 years. FM and FFM were measured by dual x-ray absorptiometry at 6 and 8 years, and normalized to height.; Results. Decreased levels of vigorous and hard physical activity were predictive of BMI at age 8 in children at high risk for obesity. Risk and physical activity interaction is suggested for children at low risk. Physical activity was not predictive of normalized FM and FFM at age 8. Physical inactivity was negatively associated with measured physical activity in low risk children.; Conclusion. Risk of overweight plays important role in the development of overweight in children, while physical activity offers more protection against overweight in low risk than high risk children.