Navigating public health research in UK secondary schools: key challenges and opportunities identified by researchers

OBJECTIVE: Conducting health research with adolescents involves navigating complex challenges at both organisational and individual levels. As part of evaluating the EACH-B (Engaging Adolescents with Changing Behaviour) intervention-a school-based randomised controlled trial aimed at improving diet and physical activity in adolescents, we explored researchers' insider experiences of programme implementation. The study investigates real-world implementation challenges and protocol adaptations in the EACH-B trial to provide practical guidance for public health interventions in schools. Applying the Consolidated Framework for Implementation Research (CFIR), data were collected through semi-structured interviews and focus groups with 10 members of the research team. RESULTS: Researchers identified significant barriers within the 'Inner' settings (internal research processes) and 'Outer' settings (external school environment and policy landscape). Research delivery was hindered by post-pandemic school priorities-specifically academic recovery and mental health support which limited the feasibility of maintaining adolescent engagement and school access. Researcher-led adaptations emerged as a critical, yet often hidden, component of maintaining trial fidelity. The study concludes that reflexive 'insider' perspectives and flexible designs are essential to align research with shifting school priorities. These adaptive strategies provide a blueprint for more resilient and feasible public health interventions.