Action 3: 30: protocol for a randomized feasibility trial of a teaching assistant led extracurricular physical activity intervention

Background
Many children do not meet physical activity (PA) guidelines. Extracurricular programmes could provide a mechanism to increase the PA levels of primary-school-aged children. Teaching assistants (TAs) are a valuable resource in all UK primary schools and could be trained to delivery after-school PA programmes. The aim of this feasibility study is to examine whether the Action 3:30 PA intervention, which is delivered by TAs, could be effective in increasing the PA of Year 5 and 6 children.

Methods/Design
A feasibility trial will be conducted in 20 primary schools. Schools will be randomly assigned to intervention or control arms. Intervention schools will receive a 25-hour TA training programme for two TAs, a first-aid certificate course for two TAs; ongoing TA support; 40 one-hour session plans that can be delivered by TAs; Action 3:30 clubs that run twice a week for 20 weeks; and ten sets of parent information sheets that are distributed biweekly.

All measures will be assessed at baseline (Time 0), at the end of the intervention period (Time 1) and four months after the intervention has ended (Time 2). As this is a feasibility study, our primary interest is in estimating the recruitment of schools and children, adherence to the intervention, and completeness of data collection for outcomes and costs.

As the most likely primary outcome measure in a future definitive trial will be accelerometer-determined minutes of moderate-to-vigorous PA (MVPA) per day, participants will wear accelerometers for five days (including two weekend days). Several psychosocial variables that could act as mediators in a future trial will be assessed via a questionnaire. Process evaluations of the session attendance, perceived enjoyment and perceived exertion will be assessed during the intervention. At the end of the intervention period, qualitative assessments will be conducted to identify how the programme could be improved before proceeding to a larger trial.

Discussion
The goal of the feasibility trial is to assess the potential of this innovative intervention approach and provide all the information necessary to design a cluster randomized controlled trial.