Effectiveness of school-based interventions targeting physical activity and sedentary time among children: a systematic review and meta-analysis of accelerometer-assessed controlled trials.

OBJECTIVES:To date, no meta-analysis has examined the influence of specific intervention characteristics in the overall effectiveness of school-based interventions measured only with accelerometer devices. Thus, the main purpose of this systematic review and meta-analysis was to evaluate the overall and specific variables of the effectiveness of school-based interventions assessed with accelerometer devices among children aged 5-12 years. STUDY DESIGN:A systematic review and meta-analysis to assess the effectiveness of school-based interventions. METHODS:Studies published in English, French and Spanish from five electronic databases between January 2010 and December 2021 were identified. Intervention designs with control group measure that assessed daily moderate-to-vigorous physical activity (MVPA) and sedentary time (ST) with accelerometer devices in children aged 5-12 years were included. PROSPERO ID:CRD42022326859. RESULTS:A total of 24 trials comprising of 19,487 children (51.3% girls) were included. Intervention studies were ineffective for improving daily MVPA (Hedges' g = 0.07, 95% confidence interval [CI] -0.03 to 0.17; I2 = 84.80%) but were effective for reducing ST (g = -0.08, 95% CI -0.12 to -0.03; I2 = 20.94%). Also, subgroup analyses for MVPA revealed that when studies had two intervention components (g = 0.21, 95% CI 0.06-0.36; I2 = 77.67%), and high quality (g = 0.12, 95% CI 0.01-0.22; I2 = 88.30%) they were effective. CONCLUSION:School-based interventions have been effective to reduce children's daily time spent in ST. There is no evidence of overall effectiveness of school-based interventions for enhancing daily MVPA in children. Nevertheless, improving the quality of interventions and interventions with two components are effective to increase students' daily MVPA.