Active Play in After-school Programmes: development of an intervention and description of a matched-pair cluster-randomised trial assessing physical activity play in after-school programmes.

INTRODUCTION: Interventions delivered in after-school programmes (ASPs) have the potential to become a means of ensuring adequate physical activity among schoolchildren. This requires a motivational climate, allowing for self-determined play. If trained, ASP staff may represent a valuable resource for supporting such play. Increasing knowledge and supportive skills among ASP staff may also potentially increase their motivation for work. The purpose of this article is to describe the development of the 'Active Play in ASP' intervention, which aims to promote physical activity among first graders attending ASP, and to present a protocol for a matched-pair cluster-randomised trial to evaluate the intervention.

METHODS AND ANALYSIS: Informed by experiences from practice, evidence-based knowledge and theory, the intervention was developed in a stepwise process including focus group meetings and a small-scale pilot test. The intervention contains a course programme for ASP staff to increase their skills in how to support physical activity through play. In a cluster randomised controlled trial, the ASPs will be matched and randomly allocated to receive the 7-month intervention or to a control group. Outcomes will be assessed at baseline, after 7 and 19 months. First graders attending the ASPs included are eligible. The primary outcome will be accelerometer-determined minutes in moderate to vigorous physical activity in the ASP. The study uses a mixed methods approach including observations and interviews to provide rich descriptions of the concept of children's physical activity in ASP. Moreover, the trial will assess whether the ASP staff benefits from participation in the intervention in terms of increased work motivation. Lastly, process evaluations of programme fidelity, satisfaction and suggestions on improvement will be performed.

ETHICS AND DISSEMINATION: The study is approved by the Data Protection Official for Research (reference no 46008). Results will be presented in conferences and peer-reviewed journals.

TRIAL REGISTRATION NUMBER: Clinical Trials (NCT02954614), pre-results.