Foot Placement in Oblique Stair Descent

Abstract

Extensive research has been conducted on stair safety as a loss of balance due to a misplaced step on a stair can result in a fall and serious injury. One aspect of stair safety that has not been well studied is oblique (angled) stair descent/ascent. Since oblique stair geometry affects the distance travelled and the theoretical symmetry of one’s stance, there are potential implications for fall risk. The purpose of this study was to investigate whether there are adaptations in foot placement that pedestrians demonstrate when descending stairs at oblique angles. Sixteen participants descended steps along two paths – 0 and 45 degrees. Kinematic data of the lower limbs were collected to calculate average step length, average step width, and toe placement. The data suggest that pedestrians compensate for angled descent by narrowing their step width and using a biased foot placement relative to the step edges, such that the inside foot (the foot furthest from the flared side) lands further forward on the step than the outside foot (the foot closest to the flared side). These variations from straight stair descent provide a more symmetric stance for oblique stair descent and may reflect adaptations to reduce the risk of a misstep.