Mismatch between Actual and Perceived Sense of Slip Detrimentally Influences Postural Stability in Older workers

Age-associated impairment of proprioception and decreased sensitivity to underfoot pressure, may have serious problems for the elderly for their ability to “correctly” judge or perceive the degree of slipperiness, while walking on an inclined slippery surface, such as a ramp. The present study focuses on investigating the role of age-associated influences on workers’ ability to perceive surface slipperiness and its impact on postural balance and slip and fall events while negotiating a ramp. The study was carried out on 32 younger and 33 older workers. All workers’ postural balance and slip/fall events were objectively quantitated with a human motion analysis system and subjectively measured with the perceived sense of slip/fall (PSOF) tool respectively, while they walked up and down a ramp (on a level surface or 0, or at 10, 15, and 20 degrees) on 2 surface coefficient of frictions (dry: 0.76-1.06; moderately slippery: 0.19-0.21). While slip rating scores for the dry surface were comparable between the groups, the older workers significantly (p=0.046) underestimated the slippery surface. The deviation of the subjective surface slipperiness rating from the mean (DSSSR) for each surface was calculated. As expected, the older workers’ objective measure of postural balance was poorer than the younger group when they negotiated the slippery ramp surface. Repeated measure logistic regression analysis showed that the younger group was more likely to slip but much less likely to fall as DSSSR increased. Therefore, a mismatch between perception of slippery surface risk and the actual risk may jeopardize workers’ ability to safely negotiate a slippery ramp surface and thereby make them more susceptible to slip-related fall-injuries.