Physical reserve: Construct development and its utility in predicting physical and cognitive outcomes
Date
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
YU Faculty Profile
Abstract
Physical reserve (PR) refers to one’s ability to maintain physical functioning despite age, illness, or injury. The measurement and predictive utility of PR, however, are not well established. Objective: We quantified PR using a residual measurement approach by extracting standardized residuals from gait speed, while accounting for demographic and clinical/disease variables. We then used this measure of PR to predict fall-risk and incident fall-risk among older adults. In addition to physical outcomes, we also examined whether PR was associated with executive functioning scores, both cross-sectionally and longitudinally. Methods: Participants (n=511; age 65+) were enrolled in a longitudinal study. Falls were assessed annually (in-person) and bimonthly (via structured telephone interview). Results: General Estimating Equations (GEE) revealed that higher baseline PR was associated with reduced odds of reporting falls over repeated assessments in the total sample and incident falls among those without a history of falls. The protective effect of PR against fall-risk remained significant when adjusting for multiple demographic and medical confounders. Linear regression models revealed that higher PR was associated with better baseline scores on executive functioning measures. We found that higher PR predicted reduced odds of performing 1.5 SD or more below the mean on executive functioning measures over the follow up period. Discussion: We propose a novel framework to quantify and assess PR. Findings suggest that higher PR is protective against fall-risk in older adults, is positively associated with executive functioning scores, and can be useful in predicting meaningful decline in key measures of executive functioning.