The impact of age, surface characteristics, and dual-tasking on postural sway.

Postural control integrates somatosensory, vestibular, and visual input to maintain balance. Age, dual-tasking (DT), and varying surfaces may impact postural control and lead to falls. Research suggests smartphone use is a growing safety hazard, as it reduces situational awareness while increasing dual-task costs (DTCs). Therefore, we examined postural control using a modern, motor-cognitive, dual-task paradigm and examined DTCs associated with age, surface characteristic, and type of DT. Younger (n=24) and older (n=26) participants completed three 30- second trials of six different task conditions. Participants either stood quietly (single-task) or performed a secondary, word generation task (dual-task) that included verbally listing words (verbal) or typing words (texting) on a smartphone within a given category (e.g., vegetables) while on a firm, stable surface (level floor) or compliant, unstable surface (foam pad). Repeated-measures MANOVAs tested differences in postural sway (measured by sway angle, velocity, and acceleration) between age groups and task conditions. Results indicated poorer performance on the verbal DT than texting DT while standing on the level floor; performance was similar between the two DTs when standing on the foam pad. We also found poorer performance on the foam pad compared to level floor while texting; performance was similar between surfaces for the verbal DT. Younger adults generally had better performance than older adults within each task, particularly for texting on the level floor. In summary, older age, verbal tasks, and compliant, unstable surfaces have greater impact on postural control parameters compared to younger age, texting, and firm, stable surfaces.