Foot clearance in young and older adults when negotiating an obstacle.

Background: Stepping over obstacles when walking is a common placing the foot close to the obstacle. Objective: Thesis aim was to determine when crossing an obstacle if: a) the repeatability of foot clearance parameters; b) foot clearance parameters were symmetrical; c) there were a difference in foot clearance parameters for different height obstacles and when performing a dual task; d) if there were a difference between sexes; and e) older adults stepped over an obstacle differently compared to younger adults. Methodology: 20 healthy young adults and 10 healthy older adults performed four walking tasks (LOW/HIGH obstacles and HIGH/LOW Dual Task) at their chosen speed. The dual task involved holding a glass of water while walking. Markers were placed on the feet to aid identification of foot clearance parameters (toe height, heel height, and step distance away and in front of the obstacle). Results: For aim a) moderate to excellent reliability for all foot clearance parameters; b) Most foot clearance measurements were symmetrical; c) foot clearance parameter were impacted by the height of the obstacle and the inclusion of a dual task; d) sex differences were broadly removed once normalized to height; e) older adults showed significantly closer step distance from obstacles for both leading and trailing limbs and a higher toe clearance for the trailing, compared to young adults. Conclusion: Foot clearance parameters (discrete points) were repeatable and symmetrical, but further work should focus on the foot trajectory. When normalized to height there were no sex differences – an approach not commonly adopted in related literature. Older adults potentially reduced toe-tripping with the different foot placement but this may increase chance of a stumble with the heel after crossing the obstacle. Further work should develop a consistent obstacle clearance protocol to allow comparisons across studies.