Being physically active is good for children’s physical and mental health. Few adolescent girls are active enough to get these health benefits and teenage girls face lots of barriers to being physically active. Research shows that most school-based programs to increase adolescents' physical activity do not work, however, few good quality studies have been tried in the UK and new approaches are needed.

As children move into adolescence, friends’ opinions and activity levels become very influential on their beliefs about and levels of physical activity. If we can harness the power of peer-influences to have a positive impact on adolescent girls’ activity, then this could be a new way to inspire girls to become and stay active. We know that peer-led anti-smoking projects can reduce teen smoking rates. In these projects, teens nominate peers who they think are influential and who they respect, to be peer-supporters. These pupils then attend out-of-school training about smoking and then are asked to return to school for 10 weeks and have informal conversations with their peers to persuade them not to smoke or to quit. In the Plan A study we have adapted this idea to develop a project to train girls to influence their friends’ physical activity.

Intervention development and piloting

We worked with adolescent’s girls to develop the PLAN-A intervention. The project is based on the peer-nomination, peer training, and 10-week informal conversation process that the smoking cessation study was. Peer supporters are trained by experts in physical activity and youth work. These girls then share the messages with other girls in their year group. Between 2015 and 2017 we conducted a pilot of the intervention in 6 schools. Girls in 4 schools received the PLAN-A intervention while girls in the 2 comparison schools did not receive the program. We used accelerometers (small wearable activity monitors) to measure how much physical activity girls in the 6 schools did before the schools were chosen to be project or comparison schools, straight after the 10-week project, and 1 year after the first measurements. Analysis of these findings showed that there was some evidence that girls in the intervention group obtained more physical activity 1-year after the first measurements but more work with a larger sample is needed. We also talked to the girls, school staff and trainers and identified ways in which the program could be improved.

Definitive trial

The project will soon move into a new phase in which we will conduct a larger evaluation of the PLAN-A intervention in 20 secondary schools. In this study we will work with Year 9 girls.  Ten schools will receive the PLAN-A intervention and there will be 10 comparison schools. We will assess the physical activity levels of all pupils before the schools are chosen to be project or comparison schools, and 1 year after the first measurements. We will also measure motivation for being active using questionnaires and how much it costs to run the project. We will do interviews and group discussions with the peer-supporters, pupils, and trainers to find out what was successful and what could be changed about the project.  

More information will be provided on this website shortly. In the meanwhile, if you would like to know anything else about the study please contact the Principal Investigator, Prof Russ Jago  (tel: 0117 9546603. Email:

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