Effects of walking environments on the objective and subjective gait measures during dynamic task performance

The objectives of this study were to evaluate the use of the center-of-gravity-based and center-of-pressure-based gait measures associated with loss of balance as well as the use of perceived sense of postural sway and instability (PSPSI) for the prediction of slip occurrence during dynamic task performance. The objective gait measures were determined by a multi-camera body motion analysis system and a strain gauge force platform. Twenty six trials performed by 21 subjects were collected for two walking environments in a laboratory-based experimental set-up. Two environments included the best (walking straight on a dry surface in good lighting) and the worst (walking straight on a slippery surface with a 2.3 Kg weight in the hand in poor lighting). Among the gait measures used in the study, it was found that the maximum distance between the center of pressure and the center of the base of support (OPmax) and the slide distance were the significant predictors of slip occurrence. An increase in the OPmax or slide distance indicates an increased likelihood of slip occurrence. The walking environment was found to have a significant effect on the PSPSI scale. It appears that the subjects were able to distinguish the difference in the walking environment but unable to perceive the potential hazards related to slips/falls during dynamic task performance. A comparison between the OPmax and slide distance (objective measures) and the PSPSI scale (subjective measure) can be used to predict a mismatch between the subjective perception of slip potential and the actual risk of slipping during task performance on a slippery surface.