Comparisons of Spatial-Temporal Characteristics between Young and Old Adults While Walking: Factors Influencing the Likelihood of Slip-Initiation

A laboratory study was conducted to evaluate if two different age groups(young vs. old) had differences in walking velocity and heel contact velocity and, furthermore, if these gait characteristics could adversely influence initial friction demand characteristics(i.e. RCOF) and the likelihood of slip-initiation. Twenty eight(14 younger and 14 older adults) participated in the study. While wearing a safety harness, all participants walked at their preferred gait speed for approximately 20 minutes on the linear walking track(1.5m×20m) consisting of two floor-mounted forced plates. During subsequent 20 minutes, synchronized ground reaction forces and posture data were captured using the two force plates and six infrared cameras, respectively. The results indicated that older adults walked slower(i.e., slower whole body center-of-mass velocity), exhibited lower heel contact velocity, and produced lower initial friction demand characteristics (i.e. RCOF) in comparison to younger adults. However, ANCOVA indicated that the differences in heel contact velocity between the two age groups were due to the effects of walking velocity. The bivariate analysis further suggested that walking velocity was correlated to RCOF and heel contact velocity, while heel contact velocity was not found to be correlated to RCOF. In conclusion, younger adults' RCOF was higher than their older counterparts due to faster walking velocity. As such, walking velocity could be a better indicator for predicting initial friction demand characteristics(i.e. RCOF) not heel contact velocity. Keyword: Walking velocity, Age, Friction demand, Gait