# Effects of Acute Exposure to Virtually Generated Slip Hazards during Overground Walking
## 4 Discussion  
The purpose of the current study was to investigate differences in lower extremity joint kinematics when exposed to REAL and VR environments. Previous literature has investigated changes in static and dynamic postural stability after being exposed to VR in the elderly, diseased, and injured [26; 38; 39]. Additionally, several researchers have examined gait characteristics and joint kinematics when exposed to slip events during loaded conditions and unloaded conditions [40; 41]. However, to the authors' knowledge, comparisons of lower body joint kinematics during real-world exposure to slip hazards and virtually generated slip hazards during overground walking have not been performed. The current study was unique due to the fact that it utilized an exact replica virtual environment of the laboratory used for data collection, promoting the most realistic immersion possible. The findings of the current study revealed no significant differences in knee and ankle joint kinematics of the slipping leg when exposed to real-world and virtually generated slip hazards. Previous literature has demonstrated the effectiveness of using VR for locomotor rehabilitation and balance training following a stroke [22; 42]. In addition, VR has been shown to be effective in improving reaction time in the elderly when exposed to various slip contaminants [33]. However, while previous studies have assessed gait characteristics and lower extremity joint kinematics while immersed in a VR environment while walking on a treadmill [43; 44], no studies have assessed lower extremity joint kinematics during overground walking while immersed in a VR environment that is an exact replica of the physical environment, further adding to the uniqueness of the current study. Similar to [PERSON] et al. [43], who compared lower extremity joint kinematics between a real environment and virtual environment during treadmill walking, the current study did not reveal any significant differences in knee or ankle joint kinematics during overground walking between the REAL and VR environmental conditions. The lack of significant differences may be due to the similarities between environments. Additionally, previous literature has shown differences in gait biomechanics when a slip contaminant is expected compared to when it is unexpected [45]. However, the current study did not reveal any significant differences between unexpected slip hazard exposure and expected slip hazard exposure. Previous literature has shown that gait kinematics are often preserved when exposed to various slip events when wearing slip-resistant shoes [46]. Therefore, the participants' use of slip-resistant shoes during gait trials is a possible explanation for the preservation of gait kinematics when exposed to slip hazards. Figure 6: Time to completion for all three Timed Up-and-Go (TUG) variations in each at baseline (BL) and after exposure to REAL and VR environments. Significance differences are indicated with *. Additionally, this study attempted to determine the effects VR exposure may have on dynamic postural stability by using several TUG variations. The results revealed significantly improved TUG-C scores after being exposed to slip hazards in a VR environment. Primarily, TUG is used in clinical settings and involves a certain amount of dynamic postural stability, often used to determine fall risk in a diseased population and the elderly [47]. However, TUG-C and TUG-M have been recently used in research settings due to the dual-task nature associated with each variation, suggesting a greater real-world application compared to the standard TUG [48]. Because of the variability of occupational environments, the increased complexity of the TUG-C and TUG-M seem to be more reliable than the standard TUG for assessing dynamic postural stability for occupational populations.