Location of minimum foot clearance on the shoe and with respect to the obstacle changes with locomotor task

Minimum foot clearance (MFC) as it relates to trips and falls has been extensively studied across many locomotor tasks, but examination of this body of research yields several studies with conflicting results and a wide range of MFCs within tasks. While there are several factors that may affect the MFC variability across studies (populations studied, environmental conditions, etc.), one aspect of the discrepancies in the literature may be the result of different placements of shoe markers and/or MFC calculation methods. A marker on the toe is often used, but may only quantify one aspect of how the foot actually clears the trip hazard. The purpose of this study was to determine the location on the shoe where MFC occurs during locomotor tasks with the highest risk of tripping. Ten young adults performed three trials of locomotor tasks which included overground walking, obstacle crossing, level change and stair negotiation. Clearance was calculated for 72 points on each shoe, including those most commonly used in past research. The location of the overall MFC on the shoe sole differed both between limbs and across locomotor tasks. Additionally, the region of the obstacle, step or stair over which the MFC occurred varied both within and across task. Use of this 3D MFC methodology provided further insight into which portions of the shoe may come closest to the tripping hazard. Future research should examine whether the location and value of the MFC changes between different populations, or with environmental modifications.