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.

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abstract: Injuries and death associated with fall incidences pose a significant burden to society, both in terms of human suffering and economic losses. The main aim of this dissertation is to study approaches that can reduce the risk of falls. One major subset of falls is falls due to neurodegenerative disorders such as Parkinson’s disease (PD). Freezing of gait (FOG) is a major cause of falls in this population. Therefore, a new FOG detection method using wavelet transform technique employing optimal sampling window size, update time, and sensor placements for identification of FOG events is created and validated in this dissertation. Another approach to reduce the risk of falls in PD patients is to correctly diagnose PD motor subtypes. PD can be further divided into two subtypes based on clinical features: tremor dominant (TD), and postural instability and gait difficulty (PIGD). PIGD subtype can place PD patients at a higher risk for falls compared to TD patients and, they have worse postural control in comparison to TD patients. Accordingly, correctly diagnosing subtypes can help caregivers to initiate early amenable interventions to reduce the risk of falls in PIGD patients. As such, a method using the standing center-of-pressure time series data has been developed to identify PD motor subtypes in this dissertation. Finally, an intervention method to improve dynamic stability was tested and validated. Unexpected perturbation-based training (PBT) is an intervention method which has shown promising results in regard to improving balance and reducing falls. Although PBT has shown promising results, the efficacy of such interventions is not well understood and evaluated. In other words, there is paucity of data revealing the effects of PBT on improving dynamic stability of walking and flexible gait adaptability. Therefore, the effects of three types of perturbation methods on improving dynamics stability was assessed. Treadmill delivered translational perturbations training improved dynamic stability, and adaptability of locomotor system in resisting perturbations while walking. / Dissertation/Thesis / Doctoral Dissertation Biomedical Engineering 2019