Background: We investigated the effect of the Whole of Systems Trial of Prevention Strategies for Childhood Obesity (WHO STOPS) intervention on children's objectively measured physical activity and sedentary time (ST). Methods: We conducted a cluster randomized controlled trial with children in grades 4 (∼9-10 years old) and grade 6 (∼11-12 years old) from 10 communities in the Great South Coast region of Victoria, Australia. Communities were randomly allocated (1:1) to receive the WHO STOPS intervention in 2015. WHO STOPS was a whole of community systems-based approach to preventing childhood obesity. Outcome data were collected using a repeat cross-sectional design in 2015, 2017, and 2019. Children were asked to wear a hip-mounted accelerometer for 7 days. Age-specific Axis 1 activity counts were converted into duration (minutes/day) spent engaged in moderate-to-vigorous physical activity (MVPA), light physical activity (LPA), and ST. Linear mixed regression models were fitted to estimate the effects of the intervention on the three activity outcomes across the study period. Results: Analyses were based on valid accelerometer data from 1406 children (intervention n = 745; control n = 661). Results for MVPA, LPA, and ST were nonsignificant. Between 2015 and 2017, there were positive, but nonsignificant, changes in mean MVPA favoring intervention boys [3.7 minutes/day; 95% confidence interval (CI): -5.7 to 13.1] and girls (5.5 minutes/day; 95% CI: -1.5 to 12.6). By 2019, these effects had attenuated. Conclusions: Although the WHO STOPS intervention did not significantly change activity levels, the magnitudes of the effects on MVPA suggest that further research with whole-of-community interventions in larger samples would be worthwhile. Clinical trial registration: Australian New Zealand Clinical Trials Registry (ANZCTR.org.au) identifier 12616000980437.
Keywords: accelerometry; childhood obesity; community-based prevention; physical activity; sedentary behavior; systems science.