INCREASED DIFFICULTY OF DUAL-MOTOR TASKS EFFECTS STEP LENGTH IN YOUNG AND OLDER HEALTHY ADULTS

Many adults have difficulty doing two things at once, especially walking and completing another motor task. In older adults, this could lead to a fall. Further, falls during walking have been associated with changes in gait variability or the natural stride-to-stride fluctuations while walking. The aging process contributes to a more variable gait cycle, which contributes to falls, and has been used to predict falls occurrence. This project investigated the effect of task difficulty during dual-motor tasking on gait variability in young and older healthy adults. Fifteen young adults (20.6 ± 2 years, 167.4 ± 6.5 cm, 65.0 ± 5 kg), and five older adults (72 ± 3 years, 169.2 ± 13.3 cm, 68.7 ± 10.9 kg) completed of a series of dual-task conditions, 3½ minutes each, where the opaqueness of the tray and/or the amount of water in glasses on top of the tray (task difficulty) varied while walking on a self-paced treadmill. For each condition: sample entropy was calculated on step length, step time and step width. Older adults showed significantly less repetitive step length values than young adults (p=0.04). Step length was less repetitive during baseline walking as compared to conditions in which vision or task difficulty was altered (p’s=0.005, 0.021, 0.006,