Older Adults' Experiences of a Physical Activity and Sedentary Behaviour Intervention: A Nested Qualitative Study in the SITLESS Multi-Country Randomised Clinical Trial.

Background: The SITLESS programme comprises exercise referral schemes and self-management strategies and has been evaluated in a trial in Denmark, Spain, Germany and Northern Ireland. The aim of this qualitative study was to understand the implementation and contextual aspects of the intervention in relation to the mechanisms of impact and to explore the perceived effects.

Methods: Qualitative methodologies were nested in the SITLESS trial including 71 individual interviews and 12 focus groups targeting intervention and control group participants from postintervention to 18-month follow-up in all intervention sites based on a semi-structured topic guide.