RESUMEN
BACKGROUND: It is unclear how young and older adults modulate dual-task mobility under changing postural challenges. AIM: To examine age-related changes in dual-task processing during specific phases of dual-task Timed Up-and-Go (TUGdual-task). METHOD: Healthy young and older adults performed the Timed Up-and-Go (TUG) with the following dual-task conditions: (1) serial-three subtractions, (2) carrying cup of water, (3) combined subtraction and carrying water, and (4) dialing cell phone. The primary outcome was the dual-task cost on performance of TUG (percent change from single- to dual-task) based on duration and peak trunk velocity of each phase: (a) straight-walk, (b) sit-to-stand, (c) turn, (d) turn-to-sit. Mixed-design univariate analysis of variance was performed for each type of task. RESULTS: Older adults had more pronounced mobility decrements than young adults during straight-ahead walking and turns when the secondary task engaged both cognitive and manual modalities. Simple cognitive or manual tasks during TUGdual-task did not differentiate young from older participants. Subtraction performance during simple and complex cognitive conditions differed by phase of the TUG. Manual task performance of carrying water did not vary by phase or age. DISCUSSION: Our findings suggest that dual-task processing is dynamic across phases of TUGdual-task. Aging-related dual-task decrements are demonstrated during straight-ahead walking and turning, particularly when the secondary task is more complex. CONCLUSION: Older adults are susceptible to reduced dual-task mobility during straight-ahead walking and turning particularly when attentional loading was increased.