ABSTRACT
Sedentary behavior is associated with overweight and obesity in children, and distance to school has been negatively associated with active commuting to school. It is not known how distance to school relates to sedentary behavior in children. The aim of this study was to investigate the association between distance to school and children's sedentary behavior during weekdays at times where children interact with the neighborhood environment. Children (5-13 years, n = 295) who participated in the understanding relationships between activity and neighborhoods study (2008-2010) across four New Zealand cities wore a hip-mounted accelerometer for 7 days. Minutes spent sedentary (accelerometer count <100 min(-1)) were derived for the school travel periods (0800-0859 and 1500-1559) and after school discretionary time (1600-1759). Shortest street network distance to school was calculated from residential addresses using geographical information systems and parsed into tertiles for analysis. Children completed a daily travel log including mode of transport to and from school, which was dichotomized into active (walking and cycling) and passive (motorized) modes. Children living in the second tertile of distance from school were the least sedentary during the school traveling periods (42 ± 10%, mean ± true between-child SD) compared to those living in the first or third distance tertiles (47 ± 10 and 49 ± 10%, respectively); the differences were clear and likely substantial (90% confidence limits ± 6%). Children who traveled by motorized transport were more sedentary for each of the distance tertiles (50 versus 44%, 46 versus 39%, and 54 versus 27% for first, second, and third tertiles, respectively; 90% confidence limits ± 7%). In the period of 1600-1759, girls in the third distance tertile were the most sedentary. The combined effects of 1-2 km distance from school and active commuting to school contributed to least sedentary time in children.
ABSTRACT
OBJECTIVES: To examine in the context of a school day whether a pedometer, compared to an accelerometer, was an effective tool to identify children with low physical activity levels. Additionally, to characterise within the school day, patterns of variation in level and timing of activity of the most active and least active children. DESIGN: Observational study to compare two methods (accelerometer and pedometer) of identifying less active children and intensity of activity. METHOD: During school hours, for three consecutive days, children (n=47, aged 8-11 years) in two classes wore an accelerometer and sealed pedometer. Accelerometers were programmed to record at 15s epochs and the number of pedometer steps taken were recorded at the end of each school day. Patterns of activity by total accelerometer counts, and with cutoffs applied, were examined against time and the number of steps taken. RESULTS: Based on the accelerometer (>1500 counts/min), the majority (68%) of children spent more than 60 min in moderate to vigorous physical activity (MVPA) during the school day. Overall, time spent in MVPA was three times greater during break times compared to classroom time, with no apparent differences by class/age or gender. Total accelerometer counts and pedometer steps were correlated (r=0.60). One minute of MVPA was equivalent to 45 (95% CI 20 to 70) pedometer steps. CONCLUSION: The pedometer, a practical, relatively inexpensive tool, is suitable for the identification of less active children and has some utility to assess the relative intensity of activities in the context of a school day.
