# Effects of Acute Exposure to Virtually Generated Slip Hazards during Overground Walking
## 1 Introduction  
Falls are one of the leading causes of injuries and fatalities in occupational environments, along with one of the leading causes of time away from work, specifically among construction and manufacturing, making fall prevention efforts a necessity among occupational populations. Exposure to various slip hazards such as slippery or uneven surfaces and debris has been recognized as a significant influence on falls and fall-related injuries [1]. In fact, according to the Bureau of Labor Statistics (BLS), injuries due to slips, trips, and falls accounted for 46.1% of total workplace injuries in construction settings [2]. Suchinjuries can result in permanent disability, loss of earning potential, poor quality of life, and significant financial burdens for the employee and employer. Moreover, more than one-third of the total number of fatalities in the construction industry were a result of falls due to slips and trips [2]. Although there was a reduction in the number of falls in construction from 2019 to 2020 in the United States, there was a 5.9% increase from 2020 to 2021 [2]. Moreover, slips have been recognized as the most common cause of falls at the same level and have continued to show an upward trend in being the primary cause of falls and fall-related injuries by approximately 25% in the last 10 years [3]. However, an individual's fall risk is highly dependent on their physical ability to recover from the initial perturbation that triggers instability [4]. Some of the most common causes of falls and fall-related injuries are inefficient postural control strategies and the failure of normal locomotion and equilibrium in response to significant perturbations [5], resulting in a loss of postural stability, and ultimately could be a result of improper functioning of an individual's sensory feedback stimuli provided by the postural control system (visual, vestibular, and proprioception) [6; 7]. In order to prevent falls, one must be capable of producing coordinated movements across several joints to allow for proper recovery from a perturbation. Therefore, optimal coordination of one's neuromuscular and skeletal systems is critical to regain postural stability. According to the National Occupational Research Agenda (NORA) for construction, falls from a height and the same levels are top priorities for the Center for Disease Control and Prevention (CDC) [8], highlighting the significance of falls and fall-related injuries in occupational environments. The increased probability of occupational falls and the mechanisms behind such falls are complex and can involve various extrinsic environmental factors, such as walking surfaces, or individual intrinsic human factors, such as muscular fatigue, that may impact postural stability. Due to the inconsistency and variability of construction worksites, there remains a high risk of exposure to slip hazards. Therefore, gait patterns must be regularly modulated and corrected to avoid these slip hazards. Primarily, research related to fall prevention due to slips has focused on the environmental factors, including the coefficient of friction experienced by the shoe-floor interface when exposed to a slippery walking surface, which is recognized as a major predictor of slip events [9]. Heel slip distance and heel slip velocity following heel strike during human locomotion are commonly utilized to differentiate slip types and fall risk [10]. Additionally, lower extremity joint kinematics, although less common, may also be used to determine possible contributions to forward heel slipping [11; 12]. While falls related to walking are initially provoked by environmental factors such as slippery or uneven walking surfaces, slopes, etc., the fall itself is determined based on an individual's characteristics that may allow them to recover from the perturbation.