FATIG’AGE: Co-Creation And Validation Of An Ecologically Informed Daily-Activity Protocol To Assess Fatigability In Ageing Populations With Diverse Functional Profiles

Fatigue is a highly prevalent and relevant clinical parameter, and is recognized as a key determinant of vitality capacity within the Healthy Ageing framework. Within its construct, fatigability refers to fatigue that develops in response to a specific activity, which impacts performance in daily life. However, current fatigability assessments predominantly rely on isolated or single-modality tasks, which insufficiently capture the complex and cumulative demands of everyday functioning. In this study, we developed and validated FATIG’AGE, the first standardized, ecologically valid, multi-task protocol to assess fatigability in ageing and clinical populations with varying functional abilities. Using a human-centred, iterative design approach, FATIG’AGE was co-created through repeated participant testing and structured feedback, with the aim of inducing progressive increases in perceived fatigability within the one-hour timeframe. Overall the protocol was found to be safe and realistic, and during validation, it consistently elicited increasing perceived exertion across participants. Differences in perceived exertion trajectories and total task execution demonstrated discriminative potential, with lower fatigability observed in older adults without mobility impairments compared to older adults with sarcopenia and stroke survivors. Overall, FATIG’AGE provides a structured and meaningful approach to evaluate fatigability as a component of vitality capacity in both research and clinical settings.