Navigating multidimensional obstacles: a comparison between young and older adults and among obstacles

Most falls in older adults are due to tripping over objects. Older adults cross obstacles with greater toe clearance to prevent tripping, indicating obstacles may be more consequential when compared to young adults. The typical dowel rod used in obstacle crossing research is foreign and sometimes unrealistic compared to real-world obstacles. This study compared measures of obstacle crossing between young and older adults using four different obstacles. Thirty young (23 ± 4 years) and 30 older adults (69 ± 6 years) crossed four different obstacles: a branch, a parking curb, a dowel rod, and a puddle. Motion capture data was used to compute measures of toe clearance, approach/landing distances, and lower body joint kinematics. We analyzed different combinations of obstacles within the older adult group and between groups for each obstacle using analysis of variance tests with False Discovery Rate corrections applied to post-hoc comparisons. A total of 1196 young adult and 1233 older adult obstacle crossing trials were analyzed. Older individuals had greater clearance in leading toe vertical clearance across all obstacles, but only among the branch and dowel for trailing toe vertical clearance. The dowel produced the greatest leading toe vertical clearance in both groups. No differences were observed in approach/landing distances, crossing step length, or obstacle crossing speeds. Older adults crossed all obstacles with greater peak ankle dorsiflexion on the lead limb, and more trail limb peak ankle dorsiflexion for the branch and curb. Older adults exhibited higher toe clearance in both leading and trailing limbs during crossing compared to younger adults, likely from greater ankle dorsiflexion. By increasing toe clearance, older adults increase the margin of safety, decreasing the likelihood of contacting the obstacle and potentially falling. Collectively, these results better our understanding of how realistic obstacle crossing changes with age across different obstacles.