This case study aimed to generate explanations for the lack of integration of physical activity (PA) promotion in general practices of Barcelona, the capital of Catalonia. This explanatory study adopted a qualitative approach, based on three techniques; focus groups (n = 3), semi-structured (n = 25) and short individual interviews (n = 5). These approaches explored the wider environment surrounding primary care from a range of distinctive professional and personal perspectives. Participants were recruited as patients (n = 20), policy makers (n = 6), academics (n = 5), PA professionals (n = 3), medical doctors (n = 3), researchers (n = 2), media employees (n = 2) and one social worker. Phenomenological techniques were used for data coding and interpretation. Contributors confirmed the final interpretation. Three main factors underpinned the lack of integration of PA promotion approaches. PA promotion delivery rarely accounted for either patients' individual needs or the circumstances that influenced their interest in PA promotion. This was a missed opportunity in promotional consultations. There was also a lack of official support for general practitioner-based PA promotion. Finally, primary care staff intentionally isolated their practice from other professionals and/or services in the community. Community-based PA promotion could be better integrated by (i) introducing stage-based strategies, (ii) creating top-down approaches and (iii) connecting primary care with other professionals and institutions in the community.