Parent-child relationship of physical activity patterns and obesity.

OBJECTIVE: To study differences in physical activity between normal-weight and obese children, as well as parent-child associations of obesity and physical activity.
DESIGN: Cross-sectional study.
SUBJECTS: 129 obese children (67 girls and 62 boys), 142 normal-weight controls (81 boys and 61 girls), and mothers (n = 245) and fathers (n = 222) of the children.
METHODS: Physical activity was assessed by a 3-day physical activity record (children and parents), by a questionnaire (children), and by one question on habitual physical activity (parents). The data were analysed by stepwise linear and logistic regressions. Obesity was assessed from relative weight (children) and BMI (parents).
RESULTS: Parent inactivity was a strong and positive predictor of child inactivity (beta-coefficients 0.25 and 0.16, P<0.001, for mother and father inactivity, respectively). Scores of parent activity were somewhat weaker predictors of child vigorous activity hours and total physical activity level (beta-coefficients 0.13-0.25, P = 0.003-0.08). Child obesity was negatively associated with child habitual physical activity (odds ratio 0.88, P<0.001). In addition, parent obesity (body mass index > or =30 kg/m2) was another strong predictor of child obesity (odds ratio 2.38-3.50, P<0.002).
CONCLUSIONS: The present study underscores the parents' role in childhood activity patterns and obesity. A novel finding was that the parent-child relationship of inactivity appeared to be stronger than that of vigorous activity. Hence, parents who want to reduce their children's inactivity may have to pay attention to their own lifestyle.