Slip-induced fall related injuries are a serious public health issue among older adults leading to considerable mortality, morbidity, and immobility. Existing proactive exercise interventions have produced mixed results on the success of reducing fall accidents. A training intervention may be effective in reducing slip-induced falls, if it can help older adults to practice movements related to recovery responses. The purpose of this study was to evaluate two different training interventions using a moveable platform and virtual reality in order to improve reactive recovery in older adults. Thirty-six older adults were recruited and randomly assigned to three groups (moveable platform training, virtual reality training, and control). The training groups underwent three sessions including baseline slip, training, and transfer of training on a slippery surface. The control group underwent three similar sessions as the training groups, with the training session replaced with a normal walking session. Kinematic, kinetic, and EMG data were collected during all the sessions. The moveable platform training group was repeatedly exposed to simulated slips induced by anterior-posterior movement of a platform. The virtual reality training group was repeatedly exposed to perturbation induced by visual tilts in the virtual environment while walking on the treadmill. Various biomechanical and neuromuscular characteristics were identified to quantify the effects of training. The results indicated a beneficial effect of both training methods in improving recovery reactions in older adults via proactive and reactive adjustments. The reactive adjustments involved faster response to a slip perturbation mediated by reduced time for onset and peak muscle activation (specifically knee flexor), reduced knee and ankle coactivity, reduced time for peak knee, hip, and trunk angles, and angular velocity. The proactive adjustments involved an increased center-of-mass velocity and transitional acceleration of center-of-mass. The overall fall frequency was reduced in the training groups as compared to the control group through improvements in proactive and reactive responses. / Ph. D.

Each year there is an increasing incidence of slip and fall accidents, especially among the elderly population. Existing evidence has identified several aging effects related to slip and fall accidents, yet, the causes of these accidents with advancing age are still little known. The objective of this research was to investigate the factors influencing the initial phase of unexpected slips and falls in younger and older individuals. More specifically, the relationship between ankle strength, the ankle joint power to transfer the whole body center-of-mass during normal gait, and the likelihood of slip-induced falls was identified. The walking experiment and the ankle strength tests were conducted in the Locomotion Research Laboratory, Virginia Tech. Fourteen old (67-79 years old) and 14 young (19-35 years old) individuals participated in this study (7 male and 7 female for each age group).Within a subsequent 20-minute session of natural walking on a linear track, kinematic and kinetic data were collected synchronously. A slippery surface was introduced to the participant on the purpose of unexpected slip event. The ankle strength tests were performed using a dynamometer. The results indicated that ankle strength degradation in older individuals was related to the outcome of slips (i.e., higher frequency of falls). The results also indicated that older individuals' RCOF was less than their younger counterparts. However, older individuals fell more often than younger individuals. It is concluded that friction demand characteristics may not be a total deterministic factor of fall accidents. Thus, the further research should focus not only on the dynamic of slips, but also on the dynamics of falls.</p> / Master of Science

A walkway tribometer measures the coefficient of friction between flooring material and a test foot. The value of the coefficient of friction is an indicator as to whether the flooring surface is slippery and has a propensity to cause slip and falls. This study determined that one style of tribometer, an XL Tribometer, mimics the heel-to-floor interaction of the human heel strike. High speed video footage revealed that the test foot strikes the surface and rotates so that full engagement occurs before sliding thus mimicking the affect of a human ankle. The test foot accelerates forward as would be expected during a human slip event. The manufacturer’s reported impact speed of 11 in/s, when set to the operating pressure of 25psi, was found to be much lower than measured speeds of three calibrated tribometers. Three XL tribometers were tested and provided a range of impact speeds from 17.4 to 22.7 in/s (n=540) when set to the operating pressure of 25 psi. The pressure setting was found to have a significant effect on the impact speed while the mast angle had an insignificant affect. A review of human walking studies revealed a range of pedestrian heel impact speeds on the order of 19.4 to 45.3 in/s during normal human ambulation activities. These tribometers fell on the low side of this speed range. A sensitivity study showed that the measured value of the coefficient of friction tends to decrease with a higher impact speed. This COF decrease was on the order of 0.02 and below the machine resolution and considered inconsequential within the walkway safety community.

The purpose of this study is to make a survey of the liability of municipal corporations in Texas for the construction, repair, and maintenance of their streets and sidewalks, and for injuries sustained by the traveling public through defects in same.