It has been suggested that the experience of falls by older adults is closely related to their decreased foot clearance during walking. The aging effect on foot clearance, however, is inconsistent in previous studies, probably because they used few subjects and a laboratory setting. In this study, we examined the relationship between foot clearance and aging for older adults participating in the TMIG-LISA (Tokyo Metropolitan Institute of Gerontology, Longitudinal Interdisciplinary Study on Aging). The participants were 628 older adults (65 to 91 years old) living in Nangai Village located in northern Japan. The participants were classified by sex and in four age groups (aged 65 to 69 years, 70 to 74 years, 75 to 79 years, and above 80 years). They walked on an 11-meter straight walkway at their own preferred speed. The coordinates of markers attached to participants' toes and heels were measured by the Vicon-370 system (Oxford Metrics, Oxford, England) during 5 meters toward the middle of the walkway. The sampling frequency was 60 Hz. Foot clearance was defined as the lowest height of the toe trajectory during the swing phase. The foot clearance was normalized by height. The mean value of foot clearance was 16.3mm (SD: 8.9mm) for males and 13.5mm (SD: 8.4mm) for females. The normalized foot clearance mean was 0.103 (SD: 0.06) for males and 0.093 (SD: 0.06) for females. A two-way analysis of variance (sex*age group) showed that the normalized foot clearance was not significantly different between the age groups and sexes. This result suggests that further investigations are needed to elucidate the functional relevance of foot clearance of the elderly.
