Relationship between Transitional Acceleration of the Whole Body Center-Of-Mass and Friction Demand Characteristic during Gait

Abstract

A laboratory study was conducted to examine the gait changes associated with aging and the effect of these changes on initiation of slips, initial friction demand, and slip distance utilizing newly defined biomechanical parameters of slips and falls. Twenty-eight subjects from two age groups (young and old) walked around a circular track at a comfortable pace wearing a safety harness. Slippery floor surface was automatically placed on the walking track over force platforms at “unexpected” random time intervals utilizing remote controlled floor changer. Synchronized kinetic and kinematic measures were obtained on both slippery and non-slippery floor surfaces. The results indicated that older subjects step length was significantly shorter, and transitional acceleration of the whole body center-of-mass (COM) was significantly slower than their younger counterparts. Older subjects initial friction demand as measured by required coefficient friction (RCOF) was not significantly different than their younger counterparts. Additionally, older subjects slipped longer and faster than younger subjects. Bivariate correlation analyses suggested that transitional acceleration of the whole body COM was significantly related to friction demand characteristic (e.g., RCOF). These findings suggest that gait changes associated with aging (especially slower transition of the whole body COM) may affect initiation of slip-induced falls among older adults.