Data for action: the use of formative research to design a school-based intervention programme to increase physical activity in adolescents.

Formative research is a critical step for the development of interventions aimed at changing behaviours, as is the case of physical activity. This process permits obtaining detailed information about the programme application context. 'Follow the Footstep' is a quasi-experimental and longitudinal study in secondary schools, the aim of which is to increase levels of physical activity among adolescents. To inform the design of the intervention programme, formative research has been carried out to analyse the perceptions of parents, teachers and students, through six focus groups.The social-ecological model was used both to carry out the formative research and then to design the programme, including five levels of influence on behaviour (individual, interpersonal, organizational, community and political), which are important when it comes to adopting a comprehensive intervention approach. The authors describe how the results of formative research were transferred to guide the design and development of the intervention. As results indicate, parents, teachers and students agreed on a need to intervene by engaging adolescents and their close social environment. The school centre is the key organizational structure to implement this intervention, supported by professionals and the community.