Physical activity and sedentary time and their relationship to BMI in 6-9 year old European children

PURPOSE: Physical activity and sedentary behaviour are nowadays seen as independent indicators of childhood overweight. This study investigated differences in BMI z-scores between four groups created by a combination of high and low levels of moderate-to vigorous PA (MVPA) and sedentary time (ST) in 6-9 year old European children. Secondly, it was studied if weight status could be predicted by MVPA and ST at one point in time and over 2 years. METHOD: Data were used from the IDEFICS study (8 participating European countries): 3220 6-9 year olds were included in the cross-sectional study and 995 in the longitudinal study. Weight and height were measured at T0 (in 2007) and T1 (in 2009) and were used to calculate BMI z-scores. PA and ST were objectively assessed at T0 using accelerometry. The cut points of Evenson et al. were used to calculate minutes per day spent in MVPA and ST. RESULT(S): The group with MVPAlow and STlow, had higher BMI z-scores compared to children in the two groups with MVPAhigh in combination with STlow and SThigh. Furthermore, only time spent in MVPA could predict weight status in 6-9 year olds at one point in time and over 2 years. Sedentary time was no predictor of weight status. CONCLUSION(S): MVPA and not ST seems to play an important rolefin the development of childhood overweight. More research is needed in 6-9 year old children to investigate the influence of objectively measured PA combined with ST in the development of childhood overweight