Perceived physical fatigability predicts all-cause mortality in older adults

BACKGROUND: Perceived physical fatigability is highly prevalent in older adults and associated with mobility decline and other health consequences. We examined the prognostic value of perceived physical fatigability as an independent predictor of risk of death among older adults. METHODS: Participants (N = 2 906), mean age 73.5 [SD, 10.4] years, 54.2% women, 99.7% white enrolled in the Long Life Family Study, were assessed at Visit 2 (2014-2017) with 2.7 [SD, 1.0] years follow-up. The Pittsburgh Fatigability Scale (PFS), a 10-item, self-administered validated questionnaire (score range 0-50, higher = greater fatigability) measured perceived physical fatigability at Visit 2. Deaths post-Visit 2 through December 31, 2019 were identified by family members notifying field centers, reporting during another family member\u27s annual phone follow-up, an obituary, or Civil Registration System (Denmark). We censored all other participants at their last contact. Cox proportional hazard models predicted mortality by fatigability severity, adjusted for family relatedness and other covariates. RESULTS: Age-adjusted PFS Physical scores were higher for those who died (19.1 [SE, 0.8]) compared with alive (12.2, [SE, 0.4]) overall, as well as across age strata (p \u3c .001), except for those 60-69 years (p = .79). Participants with the most severe fatigability (PFS Physical scores ≥ 25) were over twice as likely to die (hazard ratio, 2.33 [95% CI, 1.65-3.28]) compared with those who had less severe fatigability (PFS Physical scores \u3c 25) after adjustment. CONCLUSIONS: Our work underscores the utility of the PFS as a novel patient-reported prognostic indicator of phenotypic aging that captures both overt and underlying disease burden that predicts death

Development and Application of a Novel Accelerometry-based Index of Performance Fatigability in Older Adults

Performance fatigability, defined as performance deterioration during a standardized physical task, is disabling and multifactorial and has been identified as an early indicator of aging and a prevalent energy disorder among older adults. Developing an objective, sensitive, and valid accelerometry-based performance fatigability measure helps us better quantify the prevalence and understand the underlying biological mechanisms of performance fatigability. Here, I aimed to 1) develop a novel accelerometry-based performance fatigability index and characterize severity and sex difference of fatigability; 2) validate our fatigability index in an external large cohort; and 3) evaluate the associations between skeletal muscle energetics and our fatigability index. In Aim 1, I developed the Pittsburgh Performance Fatigability Index (PPFI) to quantify walking-based performance fatigability using wrist-worn accelerometry in the Developmental Epidemiological Cohort Study. Conceptually, PPFI quantifies the percentage of performance decrement during a walking task by comparing area under the observed cadence-versus-time trajectory to a hypothetical area that would be observed in the absence of fatigue. PPFI scores from a fast-paced 400m walk were higher and more variable than from a usual-paced 400m walk and revealed sex differences. In Aim 2, I correlated PPFI against physical function, leg peak power, cardiorespiratory fitness and perceived fatigability in the Study of Muscle, Mobility and Aging (SOMMA), which underscored the good construct validity of PPFI. Furthermore, I used decision tree methodology to identify sex-specific PPFI cut-points that optimally discriminated 400m gait speed. In Aim 3, using SOMMA, I found lower Complex I&II-supported oxidative phosphorylation, lower Complex I&II-supported electron transfer system and maximal adenosine triphosphate production were significantly associated with higher PPFI scores and higher odds of being in a more severe PPFI severity stratum. The successful completion of these aims provided us an objective, sensitive, and valid accelerometer-based performance fatigability index to better capture performance fatigability during walking tasks. Our understanding of muscle energetics and performance fatigability also opened new horizons for future lifestyle interventions and pharmaceutical trials aimed at reducing fatigability and improving functional performance. Collectively, this dissertation aids early detection and better management of performance fatigability thus will alleviate public health burden of mobility disability among older adults

Changes in Objectively Measured Physical Activity Are Associated With Perceived Physical and Mental Fatigability in Older Men.

BackgroundLower physical activity (PA) is associated with greater perceived fatigability, a person-centered outcome. The association between change in PA and fatigability with advanced age has yet to be established.MethodsCommunity-dwelling older men (N = 1 113, age = 84.1 ± 3.9 years at Year 14) had free-living PA assessed using SenseWear Armband prospectively at Year 7 (2007-2009) and Year 14 (2014-2016) of Osteoporotic Fractures in Men Study, a longitudinal cohort established in 2000 (baseline). We categorized percent changes in PA into groups (large decline → large increase) for 4 metrics: step count, light intensity PA (LIPA, metabolic equivalents [METs] >1.5 to <3.0), moderate-to-vigorous PA (MVPA, METs ≥ 3.0), and sedentary behavior (SB, METs ≤ 1.5, excluding sleep). Perceived physical and mental fatigability were measured (Year 14) with the Pittsburgh Fatigability Scale (PFS, higher score = greater fatigability; range = 0-50). Associations between each metric of percent changes in PA and fatigability were examined using linear regression, adjusted for demographics, change in health conditions, and Year 7 step count or total PA (METs > 1.5).ResultsMen declined 2 336 ± 2 546 (34%) steps/d, 24 ± 31 (25%) LIPA min/d, 33 ± 58 (19%) MVPA min/d, and increased 40 ± 107 (6%) SB min/d over 7.2 ± 0.7 years. Compared to large decline (% change less than -50%), those that maintained or increased step count had 3-8 points lower PFS Physical scores; those who maintained or increased LIPA and MVPA had 2-3 and 2-4 points lower PFS Physical scores, respectively (all p ≤ .01). Associations were similar, but smaller, for PFS Mental scores.ConclusionOlder men who maintained or increased PA had lower fatigability, independent of initial PA. Our findings inform the types and doses of PA that should be targeted to reduce fatigability in older adults