OLYMPIC-S: Outcomes of a Life-stYle Multicomponent Physical-activity Intervention in Children - School-based Randomized Controlled Trial

Regular physical activity is important for children's physical and emotional development, but many children do not achieve recommended physical activity levels. Schools provide an appropriate environment for introducing regular opportunities for movement and for promoting healthy behaviours. Olympic School programme combines a brief daily physical activity component with gamification and health-promotion messages intended to support participation and sustained engagement.

This study will use a two-arm cluster randomized controlled design, with the school as the unit of randomization. Fifteen primary schools will be allocated to the intervention or control condition. Children in the fourth, fifth and sixth grades whose parents or legal guardians provide informed consent and who provide assent will be invited to participate in the study assessments.

For four months, intervention schools will incorporate 15 minutes of physical activity into each school day. Schools may select the time of day that is most compatible with their routine. Teachers may conduct outdoor walking or running sessions based on The Daily Mile programme or use structured movement video sessions from the Born to Move programme. The intervention is supported by a gamified web platform presenting participation as a collective journey towards the Olympic Games. The platform records activity minutes, displays progress, unlocks Olympic cities and educational content, and provides brief messages relating to physical activity, diet, hydration and sleep. Control schools will continue their usual school activities and will not have access to the intervention platform during the study period.

Quantitative assessments will be completed at baseline and immediately after the four-month intervention. The primary outcome will be moderate-to-vigorous physical activity measured using PAU-7S. Secondary outcomes will assess Mediterranean diet adherence, fruit and water consumption, sleep, emotional well-being and health-related quality of life. Platform data will be collected throughout the intervention to evaluate implementation and adherence.

Quantitative analyses will follow the intention-to-treat principle. Mixed-effects models will account for repeated measurements and the clustering of participants within schools and will include study group, time, the group-by-time interaction and baseline outcome values. Sensitivity analyses will assess the effect of missing data. Post-intervention focus groups with children and teachers from intervention schools will explore acceptability, perceived benefits, implementation barriers and opportunities for improvement. Qualitative data will be analysed thematically and integrated with the quantitative and platform-use findings.

The intervention content is intended for approximately 8-12-year-old children, but the actual lower and upper age limits should be based on the expected ages of pupils in the participating fourth-, fifth- and sixth-grade classes.

Inclusion criteria

• Enrolled in the fourth, fifth or sixth grade at a participating primary school.
• Parent or legal guardian has provided written informed consent.
• Child has provided informed assent.
• Child is able to complete the study questionnaires with the support normally available during classroom administration.
• Child is expected to remain enrolled at the participating school throughout the four-month intervention period.

Exclusion criteria

• Written parental or legal-guardian consent has not been obtained.
• The child does not provide assent or withdraws assent.
• The child cannot participate in the study assessments according to the criteria established in the approved protocol.

Teacher focus-group eligibility:

Inclusion criteria

• Teachers or other school staff who directly participated in implementing Olympic School at an intervention school and who provide written informed consent.

Exclusion criteria

• Teachers or school staff who did not participate directly in implementation or who do not consent to the audio-recorded focus group.