Lion Hearts: applying implementation mapping to plan the delivery of a family-based physical activity intervention in community CrossFit affiliates

BackgroundCommunity-based physical activity interventions face challenges in adoption, implementation, and sustainability. Lion Hearts is a family-based physical activity intervention designed to promote cardiovascular health among mothers and children aged 3–6 years. This study applied Implementation Mapping during intervention development to identify implementation determinants and develop stakeholder-informed strategies for subsequent pilot testing.MethodsThe five iterative tasks of Implementation Mapping were applied through a co-design process with seven CrossFit affiliate owner-coaches: (1) conducting an implementation needs and assets assessment and identifying adopters and implementers; (2) specifying implementation outcomes, performance objectives, determinants, and change objectives; (3) selecting theoretical change methods and implementation strategies; (4) producing implementation protocols and materials; and (5) developing a prospective implementation-evaluation plan. Two 60-min co-design sessions were conducted approximately eight weeks apart. The first elicited barriers and facilitators to adoption and delivery within affiliate settings. Audio recordings were transcribed verbatim, and three researchers reviewed and coded both transcripts using structured matrices, supplemented by facilitator notes. Findings were synthesized using rapid qualitative analysis and integrated with behavioral theory and implementation science frameworks to identify implementation determinants and develop implementation strategies and materials. This study applied the five tasks of Implementation Mapping to identify implementation determinants and develop stakeholder-informed strategies, delivery supports, and a prospective evaluation plan for subsequent pilot testing.ResultsStakeholders identified implementation determinants related to coach knowledge and self-efficacy, participant engagement and competing demands, class structure and flow, scheduling, staffing, equipment availability, and compatibility with affiliate workflows. These findings informed implementation strategies and delivery supports targeting affiliate owners and coaches, including coach training resources, structured session templates, class-flow guidance, and fidelity-monitoring tools. Performance objectives and an implementation logic model were developed to specify hypothesized pathways linking determinants and strategies to prospective implementation outcomes. An evaluation plan was developed to assess reach, adoption, feasibility, acceptability, fidelity, and maintenance during subsequent pilot implementation.ConclusionImplementation Mapping and stakeholder co-design produced a theory-informed, contextually responsive implementation package for Lion Hearts. Although implementation outcomes have not yet been evaluated, the resulting strategies, materials, and prospective evaluation plan are positioned for testing and refinement in community fitness settings.Clinical trial registrationClinicalTrials.gov, NCT07147387.