Walking as a Window to Risk and Resiliency

Abstract

Walking is fundamental to preserving health and independence. An individual's usual pace of walking is also recognized as an indicator of health, risk for dependency, and a predictor of long-term survival. Reducing gait speed by just 0.1m/sec provides important information about outcomes in older adults that goes beyond chronologic age, sex, comorbidity, and self-reported function combined. This small reduction in gate speed is significant because each individual sets the pace necessary to accommodate a host of integrated functions that allow him or her to walk. Tests like the 6-minute walk test (6MWT) for assessing severity of heart failure or lung disease, and the 5-meter walk test for assessing frailty, have become a part of our medical toolbox; both of these walking tests are performed at a usual pace, tapping into balance, muscle strength, cognition, and motor function, as well as condition-specific limitations. Although the 6MWT is of longer duration (in order to assess sub-maximal aerobic capacity), gait speed can easily be calculated from a 6MWT (distance walked in a fixed time) or a 5-meter walk test (time to walk a fixed distance). The 6MWT is also most informative in individuals with moderate or severe functional impairment. Among transcatheter aortic valve replacement (TAVR) populations, the average gait speed (0.63 m/sec) and the average 6MWT converted to gait speed (0.57 m/sec) are strikingly similar and expectedly slower than the average gait speed for non-TAVR older adults (0.88 m/sec). An individual's walking performance on a 6MWT therefore reflects a bundled assessment of disease severity as well as underlying frailty.