Table 1_Effects of age in a cognitive-motor dual task: parametric manipulations of cognitive load and motor difficulty.docx

Both age groups showed similar increases in RT with increased load, but older adults exhibited greater decreases in d′ with increased load. Age-related gait differences were observed, especially with increases in motor difficulty, but they were parameter-specific, concentrated in stride length, stride frequency and toe clearance rather than reflecting a uniform age-related decline across all gait measures. Compared with younger adults, older adults’ gait was characterized by lower toe clearances, higher stride frequencies, shorter relative stride lengths, and greater time in double support.

As motor difficulty increased, younger adults progressively adapted their gait across all incline levels, whereas older adults made these adaptations only between the lowest and higher inclines. RT and d′—both presumed to reflect executive function—were related to gait in qualitatively different ways. RT was generally associated with gait parameters, while d′ was highly specific to incline, and in one case, task difficulty.</p>Discussion<p>These findings support capacity-sharing and posture-first accounts of cognitive-motor interaction.

In addition to age-related baseline differences, executive function explains additional variance in adaptive gait responses under increasing task demands.</p>