Low back pain (LBP) is the most common symptom leading to hospitalization and medical assistance. In the US, LBP is the fifth most prevalent case for visiting hospitals. Approximately 2.06 million LBP incidents were reported during the timeline between 2004 and 2008. Globally, LBP occurrence increased by almost 200 million from 1990 to 2017. This problem is further implicated by physical and financial constraints that impact the individual’s quality of life. The medical cost exceeded $87.6 billion, and the lifetime prevalence was 84%. This indicates that the majority of people in the US will experience this symptom. Also, LBP limits Activities of Daily Living (ADL) and possibly affects the gait and postural stability. Prior studies indicated that LBP patients have slower gait speed and postural instability. To alleviate this symptom, the epidural injection is prescribed to treat pain and improve mobility function. To evaluate the effectiveness of LBP epidural injection intervention, gait and posture stability was investigated before and after the injection. While these factors are the fundamental indicator of LBP improvement, ADL is an element that needs to be significantly considered. The physical activity level depicts a person’s dynamic movement during the day, it is essential to gather activity level that supports monitoring chronic conditions, such as LBP, osteoporosis, and falls. The objective of this study was to assess the effects of Epidural Steroid Injection (ESI) on LBP and related gait and postural stability in the pre and post-intervention status. As such, the second objective was to assess the influence of ESI on LBP, and how it influences the participant’s ADL physical activity level. The results indicated that post-ESI intervention has significantly improved LBP patient’s gait and posture stability, however, there was insufficient evidence to determine the significant disparity in the physical activity levels. In conclusion, ESI depicts significant positive effects on LBP patients’ gait and postural parameters, however, more verification is required to indicate a significant effect on ADL physical activity levels.

Studies using transcranial direct current stimulation (tDCS) to enhance motor training areoften irreproducible. This may be partly due to differences in stimulation parameters across studies, but it is also plausible that uncontrolled placebo effects may interact with the true ‘treatment’ effect of tDCS. Thus, the purpose of this study was to test whether there was a placebo effect of tDCS on motor training and to identify possible mechanisms of such an effect. Fifty-one participants (age: 22.2 ± 4.16; 26 F) were randomly assigned to one of three groups: active anodal tDCS (n=18), sham tDCS (n=18), or no stimulation control (n=15). Participant expectations about how much tDCS could enhance motor function and their general suggestibility were assessed. Participants then completed 30 trials of functional upper extremity motor training with or without online tDCS. Stimulation (20-min, 2mA) was applied to the right primary motor cortex (C4) in a double-blind, sham-controlled fashion, while the control group was unblinded and not exposed to any stimulation. Following motor training, expectations about how much tDCS could enhance motor function were assessed again for participants in the sham and active tDCS groups only. Results showed no effect of active tDCS on motor training (p=.67). However, there was a significant placebo effect, such that the collapsed sham and active tDCS groups improved more during motor training than the control group (p=.02). This placebo effect was significantly influenced by post-training expectations about tDCS (p=.0004). Thus, this exploratory study showed that there is a measurable placebo effect of tDCS on motor training, likely driven by participants’ perceptions of whether they received stimulation. Future studies should consider placebo effects of tDCS and identify their underlying mechanisms in order to leverage them in clinical care.

Nearly one percent of the population over 65 years of age is living with Parkinson’s disease (PD) and this population worldwide is projected to be approximately nine million by 2030. PD is a progressive neurological disease characterized by both motor and cognitive impairments. One of the most serious challenges for an individual as the disease progresses is the increasing severity of gait and posture impairments since they result in debilitating conditions such as freezing of gait, increased likelihood of falls, and poor quality of life. Although dopaminergic therapy and deep brain stimulation are generally effective, they often fail to improve gait and posture deficits. Several recent studies have employed real-time feedback (RTF) of gait parameters to improve walking patterns in PD. In earlier work, results from the investigation of the effects of RTF of step length and back angle during treadmill walking demonstrated that people with PD could follow the feedback and utilize it to modulate movements favorably in a manner that transferred, at least acutely, to overground walking. In this work, recent advances in wearable technologies were leveraged to develop a wearable real-time feedback (WRTF) system that can monitor and evaluate movements and provide feedback during daily activities that involve overground walking. Specifically, this work addressed the challenges of obtaining accurate gait and posture measures from wearable sensors in real-time and providing auditory feedback on the calculated real-time measures for rehabilitation. An algorithm was developed to calculate gait and posture variables from wearable sensor measurements, which were then validated against gold-standard measurements. The WRTF system calculates these measures and provides auditory feedback in real-time. The WRTF system was evaluated as a potential rehabilitation tool for use by people with mild to moderate PD. Results from the study indicated that the system can accurately measure step length and back angle, and that subjects could respond to real-time auditory feedback in a manner that improved their step length and uprightness. These improvements were exhibited while using the system that provided feedback and were sustained in subsequent trials immediately thereafter in which subjects walked without receiving feedback from the system.

Mechanical impedance is a concept that is used to model biomechanical propertiesof human joints. These models can then be utilized to provide insight into the inner workings of the human neuromuscular system or to provide insight into how to best design controllers for robotic applications that either attempt to mimic capabilities of the human neuromuscular system or physically interact with it. To further elucidate patterns and properties of how the human neuromuscular system modulates mechanical impedance at the human ankle joint, multiple studies were conducted. The first study was to assess the ability of linear regression models to characterize the change in stiffness - a component of mechanical impedance - seen at the human ankle during the stance phase of walking in the Dorsiflexion-Plantarflexion (DP) direction. A collection of biomechanical variables were used as input variables. The R^2 value of the best performing model was 0.71. The second and third studies were performed to showcase the ability of a newly developed twin dual-axis platform, which goes beyond the limits of a single dual-axis platform, to quantify bilateral stiffness properties. The second study quantified the bilateral mechanical stiffness of the human ankle joint for healthy able-bodied subjects during the stance phase of walking and during quiet standing in both the DP and inversion-eversion directions. Subjects showed a high level of subject specific symmetry. Lastly, a similar bilateral ankle characterization study was conducted on a set of subjects with multiple sclerosis, but only during quiet standing and in the DP direction. Results showed a high level of discrepancy between the subject’s most-affected and least-affected limbs with a larger range and variance than in the healthy population.

There are 6 methods of persuasion: reciprocity, scarcity, authority, commitment, liking, and social proof. Although these are typically used in economic scenarios, they may be present between professors and their students as well. We surveyed ASU students to find out which methods of persuasion professors may be implementing in their classrooms, and whether or not these were effective in improving student outcomes (performance, memory, etc.).

Between 20%-30% of stroke survivors have foot drop. Foot drop is characterized by inadequate dorsiflexion required to clear the foot of the ground during the swing phase of gait, increasing the risk of stumbles and falls (Pouwels et al. 2009; Hartholt et al. 2011). External postural perturbations such as trips and slips are associated with high rate of falls in individuals with stroke (Forster et al. 1995). Falls often results in head, hip, and wrist injuries (Hedlund et al 1987; Parkkari et al. 1999). A critical response necessary to recover one’s balance and prevent a fall is the ability to evoke a compensatory step (Maki et al. 2003; Mansfield et al. 2013). This is the step taken to restore one’s balance and prevent a fall. However, this is difficult for stroke survivors with foot drop as normal gait is impaired and this translates to difficulty in evoking a compensatory step. To address both foot drop and poor compensatory stepping response, assistive devices such as the ankle-foot-orthosis (AFO) and functional electrical stimulator (FES) are generally prescribed to stroke survivors (Kluding et al. 2013; S. Whiteside et al. 2015). The use of these assistive devices improves walking speed, foot clearance, cadence, and step length of its users (Bethoux et al. 2014; Abe et al. 2009; Everaert et al. 2013; Alam et al. 2014). However, their impact on fall outcome in individuals with stroke in not well evaluated (Weerdesteyn et al. 2008). A recent study (Masood Nevisipour et al. 2019) where stroke survivors experienced a forward treadmill perturbation, mimicking a trip, reports that the impaired compensatory stepping response in stroke survivors in not due to the use of the assistive devices but to severe ankle impairments which these devices do not fully address. However, falls can also occur because of a slip. Slips constitute 40% of outdoor falls (Luukinen et al. 2000). In this study, results for fall rate and compensatory stepping response when subjects experience backward perturbations, mimicking slips, reveal that these devices do not impair the compensatory stepping response of its users.

This research seeks to present the design and testing of exoskeletons capable of assisting with walking gait, squatting, and fall prevention activities. The dissertation introduces wearable robotics and exoskeletons and then progresses into specific applications and developments in the targeted field. Following the introduction, chapters present and discuss different wearable exoskeletons built to address known issues with workers and individuals with increased risk of fall. The presentation is concluded by an overall analysis of the resulting developments and identifying future work in the field.

According to the Center for Disease Control and Prevention report around 29,668 United States residents aged greater than 65 years had died as a result of a fall in 2016. Other injuries like wrist fractures, hip fractures, and head injuries occur as a result of a fall. Certain groups of people are more prone to experience falls than others, one of which being individuals with stroke. The two most common issues with individuals with strokes are ankle weakness and foot drop, both of which contribute to falls. To mitigate this issue, the most popular clinical remedy given to these users is thermoplastic Ankle Foot Orthosis. These AFO's help improving gait velocity, stride length, and cadence. However, studies have shown that a continuous restraint on the ankle harms the compensatory stepping response and forward propulsion. It has been shown in previous studies that compensatory stepping and forward propulsion are crucial for the user's ability to recover from postural perturbations. Hence, there is a need for active devices that can supply a plantarflexion during the push-off and dorsiflexion during the swing phase of gait. Although advancements in the orthotic research have shown major improvements in supporting the ankle joint for rehabilitation, there is a lack of available active devices that can help impaired users in daily activities. In this study, our primary focus is to build an unobtrusive, cost-effective, and easy to wear active device for gait rehabilitation and fall prevention in individuals who are at risk. The device will be using a double-acting cylinder that can be easily incorporated into the user's footwear using a novel custom-designed powered ankle brace. The device will use Inertial Measurement Units to measure kinematic parameters of the lower body and a custom control algorithm to actuate the device based on the measurements. The study can be used to advance the field of gait assistance, rehabilitation, and potentially fall prevention of individuals with lower-limb impairments through the use of Active Ankle Foot Orthosis.

The phenomenon known as startReact is the fast, involuntary execution of a planned movement triggered by a startling acoustic stimulus. StartReact has previously been analyzed in simple motor movements such as finger abduction tasks, hand grasp tasks, and elbow extension tasks. More complex movements have also been analyzed, but there have been limited studies that look into functional complex tasks that require end-point accuracy. The objective of this project was to assess the ability to elicit startReact in tasks that simulate activities of daily living like feeding or picking up a glass of water. We hypothesized that a startReact response would be present in complex functional tasks, but the response would not be as accurate due to the increase in speed. Five subjects performed a simulated feeding task by moving kidney beans from one target to another where the end target changed in diameter as well as, a simulated drinking task where the subject moved a cup full of beads from one target to another. The hypothesis was supported due to a significant difference between no stimulus and stimulus trials for tricep muscle onset time, duration time, and the accuracy parameters of amount of beans dropped and weight in beads dropped. The results coincided with previous studies where subjects compensated for the change in diameter by increasing reaction time as the target diameter size decreased. The data obtained contradicted a previous study in relation to the duration time between the tasks due to our smallest diameter size having a faster duration time in comparison to the other diameter sizes. This study provides preliminary data that could assist researchers and clinicians in improving physical therapy methods for patients with impaired upper extremity motor movements.