Abstract
Background and aims
Performing multiple tasks simultaneously may result in reduced performance of subtasks (dual-task cost) particularly among old individuals. Subtask performance during dual tasking is also known to be affected by task prioritization. However, it has not been well studied how the performance of subtasks is affected during motor dual task in old adults compared to young when instructed to prioritize one task over the other. This study aims to investigate the dual-task effect on subtasks during motor dual tasking under specific instruction of task prioritization in old compared to young adults.Methods
Sixteen independent old and 18 young adults performed two single tasks (usual walking, holding a tray as steady as possible while standing) and two dual tasks (walking while holding a tray focusing attention on keeping tray as steady as possible-WTAT, and walking while holding tray focusing attention on walking-WTAW). Gait parameters [velocity and variability (coefficient of variation, CV) of stride length] and the pitch (forward-backward) and roll (side-to-side) angles of the tray were measured during the four conditions.Results
During the WTAT compared to single tasks, both young and old groups showed reduced gait velocity (β = -14.0 for old, -34.3 for young), increased gait variability (β = 0.19 for old, 0.51 for young), and increased tray tilt (β = 9.4 for old, 7.9 for young in pitch; β = 8.8 for old, 5.9 for young in roll). Higher proportion of older individuals showed higher dual-task effect on tray stability, but lower dual-task effect on gait compared to young individuals. During WTAW, there was no difference in dual-task effect between age groups in tray stability or gait performance.Conclusions
Compared to young, older adults tend to compromise the task involving upper limbs during motor dual tasking even when instructed to prioritize this task over gait. These findings may have ramifications on developing training strategies to learn or relearn complex motor activities in seniors.