Step edge highlighters and illuminance changes influence stair descent in a real-world setting.

Studies investigating the effect of tread edge highlighters on descent speed differ, but collectively report the potential benefit of reduced fall risk. Here we examine the impact of adding high-contrast black vinyl striping to the front edge of each step's tread and its impact on descending gait speed (intervention), while controlling for illumination. Descending gait speed was estimated from 5,824 video observations using the stairway length and entry and exit times. A second stairway was unaltered (control) to compare to the intervention. Stair users were primarily 18-30 years old with a small percentage being middle-aged and older adults. Descending gait speed was significantly slower on the intervention stairway (Linear mixed effects model: standardised coefficient = -0.07, 95% CI = [-0.12, -0.02],  = .010) compared to the control and may be impacted by illuminance. We propose that the slowed gait speed could be due to changes in gait kinematics (e.g. foot clearance) and may reduce fall-risk. Tread-edge contrast enhancement could be a low-cost means to reduce fall-risk on stairways, but its impact on gait kinematics is not well understood. We found that contrast enhancement reduced descending gait speed, but descending gait speed's impact on fall risk reduction ultimately requires further investigation.