Key considerations and recommendations for recruiting older adults in physical activity studies.

Background: Despite substantial evidence supporting the benefits of physical activity (PA) for older adults, participation rates remain low due to physical, psychological, social, and institutional barriers. Recruiting older adults for PA studies thus presents significant challenges, particularly for socially vulnerable populations and those facing digital literacy limitations in technology-assisted PA interventions. The present study aimed to articulate and establish a consensus among multidisciplinary and multinational PA experts regarding key considerations and requirements for designing and implementing recruitment of older adults for PA studies.

Methods: This study employed a mixed-methods consensus approach integrating a structured formal consensus process with a two-round Delphi survey. Through face-to-face and online discussions, an expert panel group formulated 104 initial recommendations regarding the recruitment of older adults for PA studies. In the first Delphi round, 42 external experts assessed the relevance of each recommendation, and recommendations with a ≥ 70% agreement threshold were considered consensual. The second round included 60 refined recommendations that were evaluated by 31 experts. A final consensus was reached through iterative expert panel discussions.

Results: Of the 104 initial recommendations, 52 (50%) met the inclusion threshold during the first round. In the second round of Delphi, 36 of the 60 revised recommendations (60%) achieved consensus, with agreement ranging from 71.0 to 96.8%. The final consensus process established 34 key recommendations categorized into four domains: (1) ethical principles (71.7-93.5%), (2) informed consent (71.0-96.8%), (3) stakeholder engagement (61.3-83.9%), and (4) recruitment strategies for technology-assisted PA interventions (74.2-87.1%). However, there remains a lack of consensus on the extent to which sociocultural diversity and differences in sample representation should be addressed.

Conclusions: This study provides expert-driven, consensus-based recommendations to improve the recruitment of older adults for PA studies. Adherence to ethical considerations, informed consent procedures, stakeholder collaboration, and tailored strategies for technology-assisted interventions were highlighted. These findings offer practical guidance for researchers and practitioners in planning and obtaining adequate participation in PA studies involving older adults.