Effects of school-based active breaks on motor competence, physical fitness, academic outcomes, and health behaviors in Chilean preschoolers: protocol for a three-arm, non-randomized cluster-controlled mixed-methods trial.

Background: Although school-based physical activity (PA) is associated with improvements in multiple health and learning indicators, significant gaps persist regarding its systematic implementation at the preschool level. This protocol presents the rationale and methodological design of a curriculum-integrated active break program aimed at evaluating its impact in 5- to 6-year-old preschoolers. Methods: A three-arm, non-randomized cluster-controlled trial employing a sequential explanatory mixed-methods design (QUAN → qual) will be conducted in 12 urban public schools in the province of Biobío, Chile, involving 200 kindergarten preschoolers. Primary outcomes-motor competence and health-related physical fitness-and secondary outcomes-learning outcomes and healthy habits (sleep, eating behavior, nutritional status)-will be assessed at baseline and post-intervention. Over 16 weeks, children in the Total Experimental Group (TEG; 4 schools, Discussion: To the best of our knowledge, this is the first controlled trial to simultaneously examine the efficacy of a curriculum-integrated active break program on motor competence, physical fitness, learning outcomes, and healthy habits in preschool-aged children. The inclusive design, digital platform support, and mixed-methods approach position this trial as a novel contribution to the evidence base for early childhood PA interventions and educational public policy. Study protocol registration: Open Science Framework (OSF). Unique identifier: cu6za. Public URL: https://osf.io/cu6za/overview.