Functional correlates of self-reported energy levels in the Health, Aging and Body Composition Study

Effects of fatigue on health in older age are well studied, yet little is known about the clinical relevance of energy perception. To explore cross-sectional associations of self-reported energy with physical and mental health metrics in the Health, Aging, and Body Composition Study. Participants rated their energy from 0 to 10; the outcome was energy dichotomized at the median (≥ 7 = higher energy). Four domains were assessed: depressive symptoms (Center for Epidemiologic Studies Depression Scale); physical performance (function: usual and rapid gait speed; fitness: 400-m walk time); physical activity (casual walking, walking for exercise, and intense exercise); and cognitive function (Modified Mini-Mental State Examination and Digit Symbol Substitution Test). Covariates bivariately associated with energy entered a multivariable logistic regression model, adjusted for demographics, chronic conditions, and strength. Depressive symptoms, physical performance and activity, but not cognition, were bivariately associated with energy (p < 0.0005). Younger age, male sex, greater strength, and absence of chronic conditions predicted higher energy (p < 0.001). In a multivariable model, depressive symptoms [adjusted odds ratio (aOR) 95% CI 0.69 (0.62, 0.76)] and 400-m walk times [aOR = 0.81 (0.72, 0.91)] were inversely associated with energy; usual and rapid gait speed [aOR = 1.3 (1.2, 1.4); aOR = 1.2 (1.1–1.4)], and time spent in intense exercise [aOR = 1.4 (1.1–1.7)] were positively associated with energy. In this cohort with a range of chronic conditions and fatigue, perceiving higher energy levels may reflect better emotional and physical health. Energy should be considered in multidimensional clinical assessments of older age.