Prior work, primarily focusing on habitual gait velocity, has demonstrated a cost while walking when coupled with a cognitive task. The cost of dual-task walking is exacerbated with age and complexity of the cognitive or motor task. However, few studies have examined the dual-task cost associated with maximal gait velocity. Thus, this cross-sectional study examined age-related changes in dual-task (serial subtraction) walking at two velocities. Participants were classified by age: young-old (45-64 years), middle-old (65-79 years), and oldest-old (≥80 years). They completed single- and dual-task walking trials for each velocity: habitual (N = 217) and maximal (N = 194). While no significant Group × Condition interactions existed for habitual or maximal gait velocities, the main effects for both condition and age groups were significant (p < .01). Maximal dual-task cost (p = .01) was significantly greater in the oldest-old group. With age, both dual-task velocities decreased. Maximal dual-task cost was greatest for the oldest-old group.
Keywords: dual-task cost; gait speed.