Results: Five context, mechanism and outcome statements were developed. (1) Improving physical activity and function is not prioritised in primary care (context). If the practice team culture is aligned to the elements of physical literacy (mechanism), then physical activity promotion will become routine
and embedded in usual care (outcome). (2) Physical activity promotion is inconsistent and unco-ordinated (context). If specific resources are allocated to physical activity promotion (in combination with a supportive practice culture) (mechanism), then this will improve opportunities to change behaviour
(outcome). (3) People with long-term conditions have varying levels of physical function and physical activity, varying attitudes to physical activity and differing access to local resources that enable physical activity (context). If physical activity promotion is adapted to individual needs, preferences and local
resources (mechanism), then this will facilitate a sustained improvement in physical activity (outcome).
(4) Many primary care practice staff lack the knowledge and confidence to promote physical activity (context). If staff develop an improved sense of capability through education and training (mechanism), then they will increase their engagement with physical activity promotion (outcome). (5) If a programme
is credible with patients and professionals (context), then trust and confidence in the programme will develop (mechanism) and more patients and professionals will engage with the programme (outcome).
A prototype multicomponent intervention was developed. This consisted of resources to nurture a culture of physical literacy, materials to develop the role of a credible professional who can promote physical activity using a directory of local opportunities and resources to assist with individual behaviour change.
Limitations: Realist synthesis and co-design is about what works in which contexts, so these resources and practice implications will need to be modified for different primary care contexts.
Conclusions: We developed a programme theory to explain how physical activity could be promoted in primary care in people with long-term conditions, which informed a prototype intervention.
Future work: A future research programme could further develop the prototype multicomponent intervention and assess its acceptability in practice alongside ex