Gait parameters as predictors of slip severity in younger and older adults

Abstract

This study investigated the association between slip severity and pre-slip gait characteristics of younger and older subjects. Sixteen younger and eleven older healthy adults walked onto an unexpectedly slippery surface. Slip severity was categorized as either hazardous or non-hazardous using a 1.0 ms peak slip velocity threshold. The results showed that hazardous slips were associated with greater step lengths (normalized by leg length) (SLR), larger and more rapidly changing foot - floor angles (FFA) at heel strike, and increased cadence across the two subject groups. Older subjects were found to walk with shorter SLR and with smaller and more slowly changing FFA at heel strike compared to younger subjects. However, both younger and older subjects experienced hazardous slips at the same rate. A logistic regression model relating SLR and cadence to slip severity predicted that increased SLR and decreased cadence would result in increased probability of hazardous slip (R2 = 0.45, chi2 = 15.30, p<0.01). A second logistic regression model relating FFA with slip severity predicted that increased FFA would result in increased probability of hazardous slip (R2 = 0.53, chi2 = 16.55, p<0.01). These results suggest that gait characteristics prior to foot contact play an important role in the severity of an ensuing slip. The finding that older adults experienced hazardous slips at the same rate as young adults even though their SLR and FFA are smaller suggests that age is also playing a role in other aspects of postural control that impact slip severity.

Effects of Nonslip Socks on the Gait Patterns of Older People When Walking on a Slippery Surface

“…In the present study, we calculated horizontal heel velocity rather than heel deceleration, which has been shown to be associated with slip events in older people. 11,25 The inclined ramp test results suggested that standing barefoot provided substantially greater slip resistance relative to nonslip and standard socks. However, these findings indicate that performance on the TUG test did not differ between the barefoot and nonslip sock conditions.…”

“…25 These variables are reported to be associated with the probability of experiencing a hazardous slip. Heel strike was identified as being the point at which the heel marker was at its lowest position in the vertical plane combined with visual inspection of threedimensional stick figures, particularly where partic-ipants walked using a toe strike or flatfoot strike gait pattern.…”

“…Kinematic outcome measures of interest were step length, 25 heel horizontal velocity at heel strike, 11 and foot-floor angle at heel strike. 25 These variables are reported to be associated with the probability of experiencing a hazardous slip.…”

Tribological Aspects of the Walking and Practical Determination of the Friction Coefficient Using a Portable Apparatus for Ground Reaction Force Analysis

“…Such studies have been performed on subjects who have walked on a known dry (traction) surface [5] The overall effect of these adaptations was a reduction in the minimum required peak COF (Redfern and DiPasquale 1997), therefore, humans have the ability to reduce the slip potential with regard to the interaction of footwear with the floor (Cham and Redfern 2002) [7].…”

Analysis of Foot Slippage Effects on an Actuated Spring-Mass Model of Dynamic Legged Locomotion

“…In the scale of metres, the largest body of work on slipping concerns human biomechanics. The conditions that cause slipping [36], its consequences [35] and dynamics [59] have been studied, with important applications in preventative care for the elderly, shoe design, safety and more. Finally, motion measurements of horses' feet during galloping revealed the existence of a significant phase of foot slippage during ground contact [58].…”