A multilevel school-based intervention on sedentary time in children: effectiveness and socioeconomic moderation...

Children's sedentary behavior is a major public health priority. While school-based programs are common, research must explore more effective approaches using robust theoretical frameworks. The CIPRES cluster-randomized controlled trial evaluated a 6-week multi-component school-based intervention combining the Socio-Ecological perspective and Trans-Contextual Model to reduce children's sedentary time (ST) and increase moderate-to-vigorous physical activity (MVPA).

Four French municipalities were cluster-randomized to either the CIPRES or Control group. Participants were children in 3rd and 4th grades. The intervention was multilevel, using co-constructed activity booklets to target school, after-school, and home settings to reduce ST. Activities were driven by TCM principles. Device-based ST and MVPA were assessed via 7-day accelerometry (accelerometers GT3X+) at baseline and post-intervention. Intervention effects and the moderating role of the Ecological Deprivation Index were analyzed using multiple constrained linear mixed models on three distinct periods (entire week, after-school and non-school days).

A total of 543 children (49.2% girls; mean age 9.2 years; 76.2% highly deprived) participated. The intervention yielded significant group*time interaction effects over the whole week, preventing the increase in relative ST (β = -1.2 percentage points [pp], p = 0.033) and improving relative MVPA (β = +0.7 pp., p = 0.034) in the CIPRES group. These effects were primarily driven by the after-school period (relative ST: β = -2.5 pp., p = 0.002; relative MVPA: β = +1.4 pp., p = 0.003). No significant intervention effects were observed during non-school days. Crucially, deprivation level significantly moderated efficacy during the after-school period: the intervention significantly decreased ST and increased MVPA primarily among highly deprived participants, while slightly deprived participants exhibited behavioral deterioration.

The theory-based CIPRES intervention effectively curbed the weekly accumulation of ST, driven by improvements during the after-school period. By predominantly benefiting highly deprived youth, it offers a promising strategy to reduce social health inequalities, though further strategies are required to effectively alter routines during non-school days.