Preschool Physical Activity Policy and Children’s Physical Activity

Importance: Evidence regarding the effectiveness of physical activity (PA) policies within preschool settings remains limited. Objective: To evaluate the effectiveness of a cocreated preschool-level PA policy on children's accelerometer-measured PA during preschool hours. Design, Setting, and Participants: This single-blind, parallel-group, cluster randomized clinical trial was performed at public preschools in Stockholm, Sweden. Of 156 randomly sampled preschools invited, 124 were randomized. Children aged 3 to 5 years with parental consent were recruited from September 14 to December 11, 2020, baseline measurements from September 23, 2020, to January 22, 2021, and 6-month follow-up from March 8 to June 11, 2021. Statistical analyses were performed from March 6, 2023, to October 25, 2024. Intervention: A cocreated preschool-level PA policy implemented for 6 months vs usual practice. Main Outcomes and Measures: Prespecified primary outcomes were between-group differences in change in moderate to vigorous PA, total PA, and steps during preschool hours, measured using wearable accelerometers. Results: Among 3751 children (mean [SD] age, 4.44 [0.86] years; 1934 male [51.6%]), 1960 attended intervention preschools and 1791 attended control preschools. All 124 preschools completed follow-up; data were available for 1530 children (78.1%) in intervention schools at baseline and 1435 (73.2%) at follow-up and 1430 children (79.8%) in control schools at baseline and 1356 (75.7%) at follow-up. Intention-to-treat analyses included 3417 children (1770 intervention and 1647 control). Moderate to vigorous PA increased from 27.4 to 33.0 minutes per day in the intervention group and from 27.6 to 33.0 minutes per day in the control group (difference in change, 0.3 [95% CI, -0.7 to 1.3] minutes per day; P = .57). Total PA increased from 177.7 to 185.3 minutes per day in the intervention group and from 176.5 to 184.5 minutes per day in the control group (difference, -0.3 [95% CI, -3.3 to 2.7] minutes per day; P = .84). Steps increased from 5415 to 5953 per day in the intervention and from 5549 to 6078 per day in the control groups (difference, 8 [95% CI, -118 to 133] steps per day; P = .90). No participants withdrew because of adverse events. Conclusions and Relevance: In this cluster randomized clinical trial, a cocreated preschool PA policy did not increase children's PA beyond usual practice after 6 months. These findings highlight the complexity of translating policy adoption into measurable behavioral change and of detecting such change in preschool settings. Trial Registration: ClinicalTrials.gov Identifier: NCT04569578.