Rationale and methods of the MOVI-HIIT! cluster-randomized controlled trial: an avatar-guided virtual platform for classroom activity breaks and its impact on cognition, adiposity, and fitness in preschoolers

IntroductionClassroom-based active breaks (ABs) have been shown to reduce sedentary time and increase physical activity in primary school children; however, evidence regarding their effects on body composition, physical fitness, cognition and other health-related outcomes remains limited in preschool children. This article describes the rationale and prespecified methods of the MOVI-HIIT study, a cluster-randomised controlled trial (RCT) evaluating a classroom-based, HIIT-inspired ABs intervention delivered through a gamified digital platform to improve body composition, physical fitness, and cognition in children aged 4–6 years. In addition, we outline a nested qualitative study designed to explore teachers’ perceptions of barriers and facilitators to programme implementation and monitoring.MethodsA RCT was conducted in nine schools in the province of Ciudad Real, Spain. Schools were randomly assigned to the MOVI-HIIT intervention group (n = 5) or the control group (n = 4). A total of 522 children aged 4–6 years were assessed at baseline (September 2022) and post-intervention (June 2023). The programme included two daily 6-minute HIIT-based ABs (20″/10″ work-to-rest ratio) guided by interactive avatars via a gamified digital platform. The primary outcomes were body composition, physical fitness, and executive function. Secondary outcomes included physical activity, sleep quality, blood pressure, and health-related quality of life. In parallel, a qualitative study using semi-structured interviews and focus groups examined teachers’ perceptions of barriers and facilitators related to the implementation and monitoring of the programme.DiscussionMOVI-HIIT represents the first intervention in early childhood education to integrate HIIT-based ABs with a gamified digital platform. Its structured, high-intensity exercise, combined with a mixed-methods process evaluation, may provide an innovative and potential reproducible model that can strengthen the evidence on classroom-based physical activity and contribute to creating active and healthy educational environments from early childhood onwards.Clinical Trial Registrationhttps://clinicaltrials.gov/study/NCT04863040, identifier NCT04863040.