The Effects of an Extemporaneous Speech Dual-task on Older Adult Gait Control

Older adults modify their gait during dual-task (DT) walking to maintain stability while completing a cognitive task, but the underlying mechanics remain unclear. Many studies use unrealistic concurrent DTs involving sensory interference or discrete (non-continuous) cognitive demands. The purpose of this study was to investigate the influence of realistic DT demands on gait control using continuous extemporaneous speech that mimics real-world cognitive demands in older adults. We analyzed changes in speech performance and spatiotemporal gait parameters, propulsion, and center of pressure (CoP) displacement and velocity in 15 older adults walking at a typical pace on a 10-meter path in two single-task (seated speech, walking only) and one DT (walking while speaking continuously on a randomly assigned topic) conditions. Linear mixed-effects regression analysis revealed no changes to speech during DT compared with seated speech (all p >  .17). In contrast, gait was significantly altered during DT compared with walking only, supporting the notion that realistic attentional demands interfere with gait in older adults, resulting in slower walking speed, shorter step length, and prolonged stance times (all p <  .001). Participants reduced both anterior-posterior CoP displacement and velocity, along with decreased propulsive force (all p  < .001), suggesting a stability-focused compensatory strategy that prioritized extemporaneous speech while controlling forward progression. The absence of changes in both medial-lateral CoP displacement, velocity, and step width (all p  > .22) indicates that lateral balance mechanisms were unchanged with DT demands, potentially through effective hip control or ankle strategies.