Contribution of the school journey to daily physical activity in children aged 11-12 years.

BACKGROUND Active travel is a possible method to increase physical activity in children, but the precise contribution of walking to school to daily physical activity is unclear. PURPOSE To combine accelerometer and GPS data to quantify moderate-to-vigorous physical activity (MVPA) on the walk to and from school in relation to overall daily levels. METHODS Participants were 141 children aged 11-12 years from the PEACH Project (Personal and Environmental Associated with Children's Health) in Bristol, England, measured between 2008 and 2009. Eighty-four children met the inclusion criteria and were included in the final analysis. Accelerometers measured physical activity, GPS receivers recorded location, and mode of travel was self-reported. Data were analyzed between April and October 2011. Combined accelerometer and GPS data were mapped in a GIS. Minutes of MVPA were compared for school journeys taking place between 8:00 AM and 9:00 AM and between 3:00 PM and 5:00 PM and in relation to whole-day levels. RESULTS Physical activity levels during journeys to and from school were highly similar, and contributed 22.2 minutes (33.7%) of total daily MVPA. In addition, MVPA on the journey did not differ between boys and girls, but because girls have lower levels of daily physical activity than boys, the journey contributed a greater proportion of their daily MVPA (35.6% vs 31.3%). CONCLUSIONS The journey to and from school is a significant contributor to MVPA in children aged 11-12 years. Combining GPS and accelerometer data within a GIS is a useful approach to quantifying specific journeys.