Joint movements associated with minimum toe clearance variability in older adults during level overground walking

Background: Approximately one-third of falls are caused by the swing foot contacting an object or the ground, resulting in a trip. The increased incidence of trip-related falls among older adults may be explained by greater within-person minimum toe clearance (MTC) variability. Research question: Will kinematic variability at any of the 6 major joints in the lower limbs, individually or in combination, be associated with MTC variability? Methods: This cross-sectional study investigated whether single or multiple joint movements best explained MTC variability in older adults. Twenty healthy older adults (7 males, 13 females; mean age = 71.3 ± 7.2 years) were recruited. Participants were fitted with a modified Cleveland Clinic marker set and walked for 50 trials at self-selected speeds over a 7-meter walkway (with a rest at 25 trials) while 6 infrared cameras recorded kinematics. Results: Seven joint movements were evaluated, and swing hip flexion-extension variability was the only joint movement significantly associated with MTC variability (r = 0.577, p = 0.008) and explained 29.6% (adjusted R²) of the variance of MTC variability in older adults (F (1, 18) = 8.897, p = 0.008). Significance: Identifying the joint movement/s associated with inconsistencies in toe clearance will improve our understanding of endpoint control in older adults and may lead to the development of effective trip prevention strategies.