The relationship between pedometer-determined physical activity, body mass index and lean body mass index in children

Objective. To cross-sectionally assess weekend to weekday variation of physical activity in British children and to consider the role of Body Mass Index (BMI,W/H-2) and Lean Body Mass Index (LBMI, H-2/W) when examining this issue. Methods. A total of 496 children aged 8-14 years, were measured for height and weight and the activity levels were analysed using pedometers to measure mean step counts for 4 consecutive days (2 weekdays, 2 weekend days). Results. Boys had significantly lower BMI than girls. Higher values for average weekend steps were associated with lower BMI values. BMI values were; however, found to be positively skewed but when the analysis was repeated using LBMI, data was normally distributed and the conclusions remained the same. Conclusions. Weekday steps are higher than weekend steps for children irrespective of gender or weight status. Mean steps taken during weekend days are significantly associated with reduced BMI in children. These findings may be questioned because BMI is highly skewed and not normally distributed. However, LBMI provides a suitable alternative that is normally distributed and can be used to compare the relationship between weight status and physical activity.