Table 2 Intervention description using the Template for Intervention Description and Replication (TIDieR) checklist

1. Brief name

CHoosing Active Role Models to INspire Girls (CHARMING)

2. Why

Less than a quarter of 11–16-year-olds meet current guidelines of being active 60 min a day. Girls are less active than boys and their physical activity levels drop quicker than male peers from the start of adolescence. The transition to adolescence is a crucial time to introduce approaches to support girls to become more active, and help stop the drop in physical activity among those who already are. The use of role models to promote physical activity has been recommended in international guidelines. Most similar studies have focused on older ages and are US-based. Better results have been shown among approaches that target girls only, are based in schools, include a range of activities, use theory and work with girls to produce a programme. A primary school-based role model programme, CHARMING, has been designed to increase and sustain physical activity levels among 9–11-year-old girls. The intervention is underpinned by psychological and sociological theory, integrating self-determination theory and the socio-ecological model.

3. What materials

Participants will have access to materials provided by the community role models following each session. Materials will signpost girls and parents to opportunities to continue the activity in their community using leaflets and usual school communication channels.

4. What procedures

Access to the intervention will be provided to schools upon randomisation to the intervention group. Schools receiving the intervention will run a 6-week programme consisting of five core planned components: 1-h taster physical activity sessions (1 per week after-school on school premises); community role model delivering the session, peer-role model(s) participating in each session, question and answer opportunity with role models post-session and sign-posting to community physical activity opportunities. All schools will have email access to the trial manager for any further enquiries.

The linked secondary school recruits a group of secondary school students to act as ‘peer role models’ for the intervention [i.e. a females aged 11–16 years who young girls might look up to as a role model for physical activity] to participate in the weekly sessions in the primary school and support girls’ engagement with the intervention.

5. Who provided

The study manager will provide community role models and peer role models with a roles and responsibilities document. A recruitment poster will also be provided to the secondary school as a means of advertising the opportunity to be involved in the programme. The teacher will be fully responsible for recruiting and selecting peer role models to participate in the programme. Schools will be advised that the number of peer role models that can be involved is flexible and that this can depend on the level of interest in the opportunity, as well as current COVID-19 restrictions and bubbles. If fewer numbers are recruited all peer role models may wish to attend all sessions but in the event of several peer role models the school may wish to alternate attendance.

6. How

Primary schools will be notified by email upon randomisation to the intervention group and will gain access to the intervention manual along with a programme timetable and list of community contacts via the trial manager. Each school will oversee the timetable planning and subsequent delivery by community role models.

Secondary schools will be notified as to whether their primary feeder school has been allocated to receive the intervention or control. In the event of intervention assignment, an introductory email will be sent to both the primary- and secondary lead teachers to formalise and facilitate the link for peer role model provision at each session.

The community role model will be provided with the school’s contact details, address, session timings and approximate number of attendees by the study manager.

7. Where

Participants will access the intervention on the primary school premises.

8. When and how much

The programme will consist of a one-hour physical activity after-school session delivered each week for 6 weeks. There will be no cost to participate.

9. Tailoring

All participants will receive the same overarching programme structure; six 1-h sessions delivered over consecutive weeks on the school premises.

In each intervention primary school, the local community physical activity provision is mapped to identify potential role models, and through communication with community providers and other physical activity stakeholders a timetable for the intervention is developed. This is done in collaboration with the school so that the interests and choices of the target population are taken into consideration when arranging the timetable.