School-based strategies to increase physical activity and reduce sedentary behaviour in students with disability: protocol of theTransformUs All Abilities hybrid type II implementation-effectiveness trial.

INTRODUCTION: TransformUs is a multicomponent school-based programme that offers teachers professional learning and resources aligned with the Australian curriculum to promote physically active teaching and learning, a supportive environment and physical activity opportunities during recess and lunch. The programme was originally developed for students in mainstream primary schools and has been proven efficacious for increasing physical activity and reducing sedentary behaviour in children without disability. The programme has been adapted for delivery with students with disabilities in primary and secondary schools (TransformUs All Abilities). This project aims to determine the implementation at scale and effectiveness of the TransformUs All Abilities programme to increase physical activity among primary and secondary school children and adolescents with disability. This protocol describes the hybrid implementation-effectiveness trial that will be used for this evaluation. METHODS AND ANALYSIS: This study employs a hybrid type II implementation-effectiveness trial to evaluate the TransformUs All Abilities programme, targeting all government and independent, primary and secondary schools in Victoria, as well as special and mainstream secondary schools in Queensland and South Australia (n=2173 eligible schools). The effectiveness trial will focus on a subgroup of government/independent special schools for students with mild to moderate intellectual disability in Victoria, involving up to three intervention and three waitlist control schools (n=61 eligible schools). In both trials, outcomes will be guided by the RE-AIM framework focusing on reach, adoption and implementation (implementation trial) and effectiveness (effectiveness trial), with data collected at baseline and 6 months. The effectiveness trial will focus on students' device-measured physical activity and sedentary behaviour-primary outcomes-and sleep, physical literacy and cognitive functions-secondary outcomes. Teacher feedback on the programme's adaptation and their experience with programme implementation will also be collected, alongside qualitative feedback from a subsample of students regarding engagement/enjoyment and suggestions for improvements. Implementation data will be analysed descriptively and using linear mixed models to test changes over time. Effectiveness outcomes will be analysed using linear mixed models to compare intervention and waitlist control, accounting for confounding and school/classroom clustering. Interview data will be thematically analysed. ETHICS AND DISSEMINATION: Ethical approval for this trial was obtained from the Deakin University Human Research Ethics Committee (2021-368). Clearance to conduct research in schools was also obtained from the Education Departments of Victoria (2023-004726), Queensland (550/27/2592) and South Australia (2022-0020). Informed consent is required for participation in the study. School staff can enrol in the implementation trial via the TransformUs website, while the effectiveness trial requires organisational, staff, parental/carer consent and student assent. Results will be disseminated through academic publications, scientific conference presentations and summary reports to schools, parents and partner organisations. TRIAL REGISTRATION: ACTRN12622001082796; Universal Trial Number: U1111-1281-1103; ACTRN12622001050741: U1111-1280-8828.