Pedometer-determined physical activity, BMI and waist girth in 7- to 16- year-old children and adolescents

Background: Different approaches to measuring physical activity and fatness in youth have resulted in studies reporting relationships ranging from very strong to non-existent. Methods: The sample comprised 787 males and 752 females aged between 7 and 16 years. Pedometer-determined physical activity, height, weight and waist girth measures were taken. Results: Significant differences were found in activity level between BMI-determined weight categories for the females (F(1, 742) = 9.07, p = .003) but not for the males (F(1, 777) = 3.59, p = .06) and between truncal adiposity groupings for both the males (F(1, 777) = 4.69, p = .03) and the females (F(1, 742) = 13.56, p = .000). Conclusions: The relationship between physical activity and body fatness differs according to the measure used and between males and females. Factors contributing to body fatness such as eating behaviours or sedentary activities may be more important among boys than girls