FATIGABILITY AS A MEASURE OF PHYSICAL RESILIENCE IN OLDER ADULTS

A better understanding of physical resilience, ability to recover or optimize function when confronted with stressors such as age-related losses or disease, is needed to develop effective successful aging strategies. Few measures of physical resilience exist; one method is to use measurable aging phenotypes, such as fatigability. Fatigability can be captured by assessing older adults’ capacity to perform strenuous physical tasks. The purpose of our study was to examine fatigability as an indicator of physical resilience in older adults by exploring its associations with recently proposed contributors to physical resilience (Whitson, 2016). This was a secondary data analysis of 163 older adults with clinically-relevant fatigue and lower extremity osteoarthritis. Participants completed questionnaires, 7-days of at-home physical activity monitoring, and functional assessments, including a test of fatigability measured via change in self-reported fatigue pre- to post-Six-Minute Walk Test (SMWT) divided by distance walked. A binary logistic regression was performed to identify relevant psychosocial and physiological contributors to high versus low fatigability (determined by median split). Low fatigability was associated with fewer chronic conditions, faster scores on the timed up and go test, and lower BMI compared to high fatigability. Fatigability was not associated with peak V02, depression, pain, or percent immobile time during home monitoring. While lab-based fatigability assessments may reflect some aspects of physical resilience, such as physical functioning, obesity, and comorbidities. Other facets of physical resilience, such as physiologic reserve, mood, symptom burden, and sedentariness, may not be captured by lab-based fatigability tests.