Schools have been identified as a promising setting for promoting physical activity (PA). Yet, to realize changes at the population level, successful school-based PA programs need to go to scale. The Svendborgproject is an effective school-based program promoting additional physical education (PE) lessons. The aim of this study is to determine program fidelity across different school groups, representing early and late adopters of the Svendborgproject, and how these are adapting the intervention. Three different school groups were identified, covering the original intervention schools and two groups of late adopters consisting of four former control schools, and five normal schools without any previous connection to the program. A PE teacher questionnaire (n = 122) was used to determine school fidelity. The results show that, while the original intervention schools have implemented the program with the highest fidelity, all schools have implemented the program with medium to high fidelity. It is suggested that having front-runner schools achieving early success with the program both strengthens political project support and provides strategies to back late adopters' implementation of the program. Furthermore, results from the current study suggest that continual promotion of the program by school heads is less important if support is established at the structural and organizational macro level. Finally, we highlight the importance of scaling up organizational capacity when scaling up program reach to assure a workable balance between fidelity and improving the fit to specific contexts.
Keywords: MRC evaluation framework CHAMPS-study DK; health promotion; implementation; physical activity; program scaling; school health.