# Effects of Acute Exposure to Virtually Generated Slip Hazards during Overground Walking
## 1 Introduction
Therefore, due to the individualistic nature of one's slip recovery patterns, it is critical to link lower extremity joint kinematics to an individual's functional anatomy to determine fall risk from slip hazard exposure [13; 14]. In general, biomechanical analyses of postural responses during slip-induced falls are performed during exposure to slip hazards during locomotion in both real-world and laboratory-based environments [11; 15; 16; 17]. With the growing popularity of virtual reality (VR), VR has been utilized as a means of assessment for postural control and stability and has been shown to be a promising tool for improving balance performance, especially among the elderly [18; 19; 20; 21]. Additionally, various movement pattern training programs involving VR have been shown to be effective in improving locomotor patterns, sensory, and muscle coordination in stroke patients [22], individuals with Parkinson's disease [23], multiple sclerosis [24], and injured individuals [25; 26], thus improving their ability to recover from slip-induced falls. Given that retention is an essential function of the central nervous system (CNS), and improvement in specific skills requires repeated exposure to cause adaptation, VR has the potential to immerse individuals in a realistic and interactive environment to allow for effective training and adaptation without the risk of injury real-world exposure may cause. Although both immersive and non-immersive VR have been shown to be effective for various purposes, immersive VR allows for a more engaging and interactive experience that can mimic real-world exposure [27]. Additionally, Timed Up-and-Go (TUG) is a quick and simple test commonly used in clinical settings to assess an individual's lower extremity function, mobility, and ability to navigate one's environment. Although often used in elderly populations, TUG can also be used in research settings in healthy adults with a dual-task component to provide a more accurate evaluation of dynamic postural stability and neurocognitive function. Dual-task TUG involving manual or cognitive components has been reported as a more appropriate measure of healthy individuals' physical abilities due to the fact that most everyday activities involve dual-task components [28; 29]. With a projected compound annual growth rate (CAGR) of 7.3% by the year 2029, the construction industry is one of the fastest-growing industries in the United States [30]. Moreover, because of the high prevalence of falls in the construction industry, there is a need to pursue feasible tools for assessments and training to promote occupational safety and health. Although initially more expensive, VR can be used for a larger number of participants for a longer period of time, reducing overall cost by hundreds of dollars per participant [31]. VR seems to be an appropriate and feasible tool for fall prevention training by exposing individuals to various situations and environments to promote greater locomotor adaptations. Previous literature has demonstrated significant improvements in postural stability and balance performance after exposure to VR [32]. Additionally, previous literature has shown similar gait characteristics and lower extremity joint kinematics when comparing real-world and VR environment exposure during treadmill walking [33]. However, to the authors' knowledge, no previous studies have compared lower extremity joint kinematics during overground walking between real-world and VR exposure where the VR environment is an exact replica of the real environment in which data are collected. Therefore, the purpose of this study was to investigate lower extremity kinematics of the knee and ankle of the slipping leg when exposed to slip hazards during real and virtually generated slip hazards during overground walking. An additional purpose of this study was to determine the effectiveness and feasibility of a fall prevention training program that involves repeated exposure to virtually generated slip hazards compared to a real environment.