Doctor of Philosophy, Miami University, 2004, Psychology

Coordination of joints has not been well studied during quiet stance or non-locomotive suprapostural activity. This dissertation consists of three experiments examining multi-segmental postural coordination. Experiment 1, tested the effect of vision and support surface on multi-segmental postural kinematics and joint angles during upright quiet stance. Eight participants stood still on four surfaces (flat, foam surface, foam roller, wood beam) with eyes open and closed. Postural motion was recorded by an electromagnetic tracking device from the head, trunk, sacrum, hip, knee and ankle. Overall postural (head) sway and joint motion was influenced by both surface of support and vision. More sway and sagittal joint rotation occurred under non-visual and non-flat conditions. An ankle strategy as opposed to a hip strategy is primary in maintaining voluntary, upright balance on non-flat surfaces. In experiments 2 and 3, surface of support (hard surface vs. foam roller) and suprapostural task (head-tracking frequency) were manipulated simultaneously. Twelve different participants in each experiment stood on each surface with hands behind their back looking at a computer monitor in front of them. They were instructed to maintain balance while tracking a simulated oscillating (fore-aft) computer target with their head at different frequencies. In Experiment 2, a rest was given between trials (frequencies), whereas no rest was given between trials in Experiment 3. The effects of discrete (rest), and changing frequency modulation (no rest) on postural dynamics were then determined. Results demonstrate that people use a continuum of coordination strategies to accomplish head-tracking at different frequencies. On both surfaces, a predominantly anti-phase, hip-ankle relationship was seen with only gradual postural transitions observed. Dynamic standing tasks exhibit many similarities in postural coordination whether performed at a singular frequency or by modulating frequency. Ho (open full item for complete abstract)

Committee: Leonard Smart (Advisor) Subjects:

PhD, University of Cincinnati, 2022, Arts and Sciences: Psychology

After stroke, physical therapists must determine when an individual requires assistance (e.g., physical support) to complete a task and when an individual can execute a motor skill with less assistance. The decision about the amount of support to provide is often based on deviations of movement patterns from expected “norms.” In standing postural control, for instance, a therapist may provide steadying support with the intent to minimize postural fluctuations, even when support is not required to maintain standing balance. When therapists view deviations from norms as “incorrect” in individuals with stroke, they make an assumption that neurotypical individuals exemplify idealized movement patterns and that any variation from that comparator represents an error in performance. “Variability as error” is a pervasive clinical assumption, but it contrasts with the complexity science perspective that motor variability is not just randomness. Variability in motor performance is now understood as an expression of flexibility, allowing an individual to select a motor strategy to fit a given context. The purpose of this study was to determine the effect of physical therapist postural assistance during the practice of an upper-limb task on task performance and underlying motor control patterns in individuals with stroke. It was hypothesized that providing unnecessary assistance (postural stabilization) during practice would result in (a) faster improvements in task performance but (b) reduced immediate retention and more limited transfer; and (c) reduced task-sensitive postural control adjustments at transfer and following practice. Individuals with chronic stroke (n = 23) who were independent in standing balance participated. Participants stood on a force plate while immersed in a virtual scene displaying an anterior target. They aimed to position a virtual laser pointer (via handheld device) in the target. All participants then engaged in a practice period whe (open full item for complete abstract)

Committee: Michael Riley Ph.D. (Committee Member); Tehran Davis (Committee Member); Paula Silva Ph.D. (Committee Member) Subjects: Experiments

PhD, University of Cincinnati, 2020, Arts and Sciences: Psychology

Individuals who are skilled in a given motor task possess the ability to reliably achieve a desirable level of performance under variations in contextual conditions, even those not previously experienced. This ability is restricted in individuals with motor control impairments (MCI), whose functional performance in a variety of tasks is disturbed by contextual change. Previous research suggests that skilled individuals are resilient to contextual change not because they have discovered (with experience) generally effective task solutions but because they learned to leverage perceptual information in task space to swiftly adjust task solutions as conditions demand. Individuals with MCI seem to increase their attentional focus to the body and use a more deliberate, visually guided style of body control, which may restrict their ability to couple task solutions to circumstance. These findings support the central hypothesis of this dissertation: the impact of MCI on performance may depend on the extent to which individuals experiencing such impairment remain flexible and adapt task solutions to contextual change. To test this hypothesis, forty-five undergraduate students performed an object transportation task in virtual reality (VR). The task consists of using a virtual pad (controlled by hand movement) to move pucks across a bridge (extending forward) and into a container. Participants were free to choose their (global) task strategy: push the pucks and carefully position them inside the container, hit the puck from its initial position or any solutions in between (e.g., push the puck a particular distance before hitting). Participants performed the transportation task while standing on a force platform which provided a measure of their postural patterns used to describe their task solution at a lower scale of analysis. Sixty-five pucks were presented in each trial. Puck presentation rate was manipulated to vary contextual conditions. To induce the experience of reduc (open full item for complete abstract)

Committee: Anthony Chemero Ph.D. (Committee Chair); Paula Silva Ph.D. (Committee Chair); Tehran Davis Ph.D. (Committee Member) Subjects: Psychology

Master of Arts, Miami University, 2009, Psychology

Prospective control can be characterized as the ability to anticipate future events and act in an anticipatory manner to arrive at a desired goal. If this process is disturbed, one must actively explore the environment to properly detect new mappings. Virtual environments are able to circumvent the limitations of the physical environment and therefore can aid in determining the boundaries of people's ability to engage in prospective control. However, it has not been shown that the behaviors exhibited in these contexts are generalizable. Participants' head motion was recorded while they navigated through a physical or virtual maze. The results indicated main effects of time and segment as well as a time x segment interaction for both yaw and pitch rotations. There was no significant difference between the physical and virtual conditions nor were there any significant interactions involving condition. These changes reflect how behavior is modified to regain prospectivity.

Committee: L. James Smart PhD (Advisor); Robin D. Thomas PhD (Committee Member); David A. Waller PhD (Committee Member) Subjects: Psychology; Technology

Master of Arts, Miami University, 2007, Psychology

The general goal of this research was to describe how people maintain postural coordination under various constraints such as stress. In particular, the goal is to see how postural coordination changes when different types of stressors are employed. To accomplish this goal, participants were asked to balance on a beam while being exposed to a stressor. Both a cognitive stressor and a perceptual stressor were used. There were three levels of stress for each stress type. It was predicted that variability and range of postural motion would be constrained as stress levels increased and velocity of postural motion would increase with increased stress level. It was also predicted that participants would exhibit more random postural motion with increased stress levels. While many of the analyses failed to reveal significant differences among conditions, the results suggest a constraining of postural motion with higher stress levels. Results also showed a complex relationship between stress and performance for postural motion.

Committee: L. James Smart (Advisor) Subjects:

Master of Science, Miami University, 2020, Mechanical and Manufacturing Engineering

Falls are prevalent in the elderly and diseased population. They are serious and costly. Numerous studies have discovered the factors contributing to falls from physiological and pathological perspectives. However, the mechanism of standing balance control with biomechanical considerations is less discussed. The purpose of this study is to investigate the fundamental biomechanics of postural control during quiet stance to determine the validity of commonly used balance models. It is hypothesized that 1) given the simple inverted pendulum model, a stable stance is preferred with a slight forward-leaning angle, and the center of pressure (CoP) would remain near mid-foot. 2) The stability diagram, expressed by the neuromuscular feedback gain and delay, will yield a wider range of parameter combinations causing a stable equilibrium position. We study the bifurcations and stability of two mathematical models: with an upright position, and with a desired leaning position. The results of the mathematical model analyses show the leaning model has a larger range of parameter values for which balance can be maintained. An analysis of experimental data of twelve healthy participants shows participants leaned forward during quiet stance. These findings provide insight into the dynamics of human balance to detect postural instability and prevent falls.

Committee: James Chagdes (Advisor); Shukla Amit (Committee Member); Walsh Mark (Committee Member) Subjects: Biomechanics; Kinesiology; Mechanical Engineering

Master of Science, Miami University, 2019, Mechanical and Manufacturing Engineering

Understanding the mechanisms behind human balance has been a prominent subject of interest as various postural instabilities have been linked to neuromuscular impairments and diseases (Parkinson's, multiple sclerosis, and concussions). This thesis presents an unsupervised method that breaks any physical model, given a sampled manifold, into its local system behaviors, and allows for the detection of intermittent instabilities in an individual's postural stance via a co-activation topological mapping scheme. The proposed co-activation topological mapping scheme is extremely powerful because it not only allows for a diagnostic analysis of an individual's postural stance through locating the mechanisms responsible for their intermittent instabilities, but for subjects who are not exhibiting intermittent instabilities. This topological mapping method is able to differentiate between stable individual's postural data.

Committee: James Chagdes Dr (Advisor); Shukla Amit Dr (Committee Member); Kramer Ryan Dr (Committee Member) Subjects: Biomechanics; Mechanical Engineering

Master of Science, Miami University, 2019, Exercise and Health Studies

The purpose of the study was to examine the effects of boxing on anticipatory postural adjustments (APAs) in healthy young adults. APAs were evaluated during pre-test and post-test to examine any changes that occurred over the 8-week boxing intervention period. 17 participants were assigned to the control group and 8 participants were assigned to the boxing group. All participants in the boxing group completed 20 sessions of boxing practice over 8 weeks with the collegiate boxing club. To assess APAs, self- initiated postural perturbations were induced using a rapid bilateral arm raising maneuver (focal movement). The onset of muscle activation was collected using surface EMG in the following five muscles: anterior deltoid (AD), thoracic erector spinae (TES), lumbar erector spinae (LES), semitendinosus (ST), and soleus (SO). The result of the study indicated that boxing training caused earlier onsets of APAs in the LES and TES, and an increased frequency of APAs in the ST and SO. The results of this experiment suggest that boxing training may be effective at enhancing anticipatory postural control.

Committee: William Berg Dr. (Advisor); Dean Smith Dr. (Committee Member); Mark Walsh Dr. (Committee Member) Subjects: Health; Kinesiology

Master of Science (MS), Ohio University, 2018, Exercise Physiology-Research (Health Sciences and Professions)

Background. Lateral ankle sprains are the most common type of injury in the sporting world accounting for approximately 30% of all injuries. Kinesiology tape is an innovative adhesive tape with elastic properties that allow the user to gain a greater sense of feel at the application point without restricting mobility. This “proprioceptive” feeling induced by the application of the tape can help to improve stability while simultaneously rehabilitating the joint applied. This can be useful in both preventing injury and stimulating repair of the joint. Objective. The purpose of this study was to examine the effects of kinesiology tape application on lateral ankle instability using the Neurocom SMART Balance Master System (Neurocom). Methods. Sixteen college-aged individuals with deficits in balance (as determined by Balance Error Scoring System) had kinesiology tape applied to the dominant ankle by a single researcher. They kept the tape applied for a time period of 48 hr. During this time, they were tested on their ankle stability and postural control using Neurcom. There were two separate conditions: taping and no taping. The testing was conducted prior to adding the condition, immediately after condition, and 48 hr after condition. Results. Neither the control condition or kinesiology tape condition had any significant effects on the variables testing. A p-value of 0.004 was set to account for Type I errors. Conclusions. Kinesiology tape had no effect on the postural control of healthy college aged individuals. Future research is warranted to see the effects on different testing modalities and populations.

Committee: Jae Yom (Advisor); Dustin Grooms (Committee Member); Janet Simon (Committee Member); Robert Wayner (Committee Member) Subjects: Health Sciences; Kinesiology; Physiology

Doctor of Philosophy, The Ohio State University, 2017, Mechanical Engineering

Cancer is a prevalent disease in our society with over 15.5 million cancer survivors in the United States in 2016. As screening and treatments improve survival rates from many cancers, increased effort is needed to address the quality of life-impairing adverse effects that result from commonly administered neurotoxic chemotherapeutic agents. These treatments can induce dysfunction in the peripheral and central nervous systems that are integral to coordinated and stable human movement. While cancer survivors are at an increased risk of falling, few details are known regarding the underlying mechanisms that contribute to this increased falls risk. Therefore, the purpose of this dissertation was to better understand the scope of functional instability in cancer survivors that result from neurotoxic chemotherapy and its adverse effects (e.g., chemotherapy-induced peripheral neuropathy, CIPN). Chapter 1 provides background information on chemotherapy-related impairments to the central and peripheral nervous systems along with an overview of human postural stability and implications for cancer survivors. Chapter 2 discusses the first longitudinal investigation into postural instability during quiet stance and gait in breast cancer patients receiving taxane-based chemotherapy. Thirty-three breast cancer patients were assessed and demonstrated balance deficits that initiated early in chemotherapy treatment (medial-lateral root mean square center of pressure excursion: 28% increase from baseline, p = 0.016) along with worsening balance and more cautious gait (5% decrease in speed, p = 0.003) with cumulative taxane exposure. We then extended our understanding by pursuing more in-depth exploratory analyses into the system-level mechanisms of balance (Chapter 3) and gait (Chapter 4) impairments associated with chemotherapy and CIPN through a case-control study design. A cohort of 20 cancer survivors provided three groups, differing by exposure to chemotherapy and presence o (open full item for complete abstract)

Committee: Ajit Chaudhari PhD (Advisor); Anne Kloos PhD (Committee Member); Maryam Lustberg MD (Committee Member); Robert Siston PhD (Committee Member) Subjects: Biomechanics; Biomedical Engineering; Mechanical Engineering; Oncology

Master of Science, The Ohio State University, 2017, Allied Medicine

Femoroacetabular impingement (FAI) is the leading cause of hip dysfunction in patients who are young and active. The single leg anterior reach (SLAR) is a common functional task clinically used to measure performance and dynamic postural control of the lower extremity. Kinetic analysis of this clinical task would provide further information regarding the postural control strategies of patients with FAI. Objective: To test the hypothesis that patients with FAI will exhibit decreased SLAR performance in the involved limb as compared to the uninvolved limb due to decreased postural control, exhibited by increased center of pressure excursion. Design: Cohort study. Settings: Movement analysis laboratory. Participants: Twenty-six patients clinically and radiographically diagnosed with FAI by a physician; 18 females (165.7 ± 8.2 cm, 66.5 ± 13.7 kg, 34.6 ± 6.8 y) and 8 males (176.6 ± 9.6 cm, 82.0 ± 12.4 kg, 37.5 ± 9.8 y). Interventions: Using a three-dimensional motion capture system and retro-reflective markers placed on the great toe of each foot, maximum SLAR distance was measured as the anterior-posterior distance between each marker at touch-down. Maximum distance was collected for three trials, averaged together, and normalized to limb length. Stance limb center of pressure (CoP) excursion was measured in the anterior-posterior (AP) and medial-lateral (ML) directions using a 40x60cm tri-axial force plate. Main Outcome Measures: Mean maximum reach distance was calculated by averaging the maximum value of the three trials for each limb. Center of pressure was calculated in the anterior-posterior and medial-lateral directions as well as total distance traveled throughout the task. Statistical differences between the involved and uninvolved limb were examined using a one-way ANOVA with an a-priori alpha level of 0.05. Results: A statistical difference with a moderate effect size (p < 0.001, d=0.328) was noted for mean normalized SLAR distance between (open full item for complete abstract)

Committee: James Onate (Advisor); Mark Merrick (Committee Member) Subjects: Sports Medicine

PhD, University of Cincinnati, 2016, Arts and Sciences: Psychology

In many everyday tasks prospectivity—the characteristic ability to foresee future events in order to control one's own behavior—essentially extends to include sensitivity to the actions of another person. In an interpersonal throwing-catching task, for example, detecting object properties and any information in actor's throw are key to anticipatorily organize one's muscular forces for a successful catch. Object properties might be visually available in kinematics (i.e., parameters of motion) of the person who is throwing the object. Few studies have investigated this ability, which is crucial to our understanding of the organization, coordination, and control of prospective action in skilled, interpersonal, perceptual-motor behavior. Therefore, the purpose of this dissertation project was to investigate prospective control of action (anticipatory muscle activity) in the context of detecting kinematic information in an interpersonal throwing-catching task. The central hypothesis of this dissertation was that people are sensitive to the kinematics of a thrower in order to extract action-relevant information to enable prospective control (anticipatory muscle activity) during an interpersonal skilled task (throwing-catching). In particular, it was hypothesized that people are sensitive to the physical properties of a ball (specifically mass) via visual kinematic information about another person's throwing actions, and this sensitivity was expected to be reflected in the catcher's anticipatory postural adjustments (APAs) in their limb muscles when catching. Three experiments were planned to test this central hypothesis. Experiment 1 was aimed at measuring APAs in a catcher when catching a ball of unknown weight thrown by another actor. The APAs were expected to exhibit a scaling relation with ball weight. Experiment 2 aimed at investigating the influence of throwing kinematics on APAs by manipulating the throwing dynamics independent of ball weight by using wrist w (open full item for complete abstract)

Committee: Michael Riley Ph.D. (Committee Chair); Michael Richardson Ph.D. (Committee Member); Kevin Shockley Ph.D. (Committee Member) Subjects: Behavioral Sciences

PhD, University of Cincinnati, 2013, Arts and Sciences: Psychology

The goal of the dissertation was to examine the loss of complexity hypothesis in context of postural control of healthy community-dwelling older adults (over 65) and younger adults with asthma (under 30). The loss of complexity provides a dynamical systems framework for understanding the relation between adaptability and complexity of a physiological (or behavioral) system and the dynamics of the resulting output from this system. It predicts that with the simplification of the system due to aging and disease (e.g., loss of functional degrees of freedom or coupling between them), the outputs measured from the system deviate from healthy irregular dynamics (characterized by 1/f-like fluctuations or intermediate entropy values) toward more regular or more irregular dynamics. I examined these ideas using the center of pressure (COP) as a variable to quantify postural control complexity in four experiments that emphasized the stabilizing capacity of the postural control system. In the first three studies, participants were required to maintain their COP on a stationary target while seeing visual feedback about their COP in real time. Two studies on aging demonstrated that older adults were not always more regular than younger adults as quantified by sample entropy. Older adults in Experiment 1 typically had more regular and more variable COP fluctuations in the feedback condition, but did not differ in COP regularity from younger adults in the no-feedback condition. Older adults with higher Berg balance scale scores also had more irregular ML COP dynamics only in the feedback condition. In the second aging experiment there were no age differences in COP regularity either when standing with equally distributed pressure or leaning more on left or right foot. The two studies on asthma also demonstrated a similar task-dependence of COP regularity differences. People with asthma were more regular in their AP COP than the controls in both feedback and no-feedback conditions o (open full item for complete abstract)

Committee: Michael Riley Ph.D. (Committee Chair); Michael Richardson Ph.D. (Committee Member); Kevin Shockley Ph.D. (Committee Member) Subjects: Experiments

PhD, University of Cincinnati, 2000, Arts and Sciences : Psychology

It has been proposed that postural movements can be controlled so as to facilitate visual performance. Tasks that require more precise visual fixations should result in a decrease in postural sway variability. Three experiments were conducted that focused on (1) differences in postural behavior when tracking a moving versus stationary target, and (2) differences in postural behavior under constraints on visual performance theoretically unrelated to eye movements in a target detection task. In the first two experiments, sway variability was reduced when tracking a moving target relative to a stationary one. In the third experiment, sway variability was reduced when performing a more difficult target detection task, but only towards the latter part of the experiment. It seems that the functional relation between body sway and task demands developed over trials. Overall results suggest that postural behavior can be used to facilitate the achievement of other tasks. Results also suggest potential postural learning for more complex tasks to achieve adequate visual performance. Implications for the design of human-machine systems were discussed.

Committee: Thomas Stoffregen (Advisor) Subjects: Psychology, Experimental

PhD, University of Cincinnati, 2009, Arts and Sciences : Psychology

Postural control typically must be coordinated in a way that is functional with regard to the control of ulterior actions. This entails the formation of coordinative structures that are appropriately flexible and, in general, the incorporation of contributions from the vestibular, visual, and proprioceptive systems. Ballet dancers are known to exhibit heightened proprioceptive awareness and enhanced levels of postural control. However, it is not known if these are related, and the coordination of dancers' body segments during balance has never been examined. The present study utilized a visual tracking task in which participants tracked the fore-aft motion of a virtual target, by standing on one leg and swaying so as to maintain an equal distance between their head and the target at all times, at frequencies of 0.20 and 0.60 Hz. Mean and SD relative phase between the ankle and hip joints were used to index coordination stability during task performance. Coordination stability during this task is generally believed to depend on proprioceptive coupling of rhythmic excursions about the ankle and hip. A joint-position matching task was used to assess proprioceptive awareness for the ankle, knee, and hip joints of both legs. An eyes-closed, quiet-standing task was also employed. Results showed that the dancers exhibited greater proprioceptive awareness in their lower limbs, and were also less variable in their ankle-hip coordination during the dynamic postural coordination task. Additionally, dancers exhibited lower determinism in the coupling between ankle and hip oscillations than controls. These results demonstrate that dancers are more sensitive to proprioceptive information in their lower limbs, and this may be an underlying mechanism driving their increased coordination stability. Dancers, through training and experience, may have become proficient at optimizing the constraints that enable them to perform complex balance tasks.

Committee: Michael Riley PhD (Committee Chair); Sarah Cummins-Sebree PhD (Committee Member); Timothy Hewett PhD (Committee Member); Kevin Shockley PhD (Committee Member) Subjects: Behaviorial Sciences; Dance; Experiments; Psychology; Sports Medicine

PhD, University of Cincinnati, 2008, Arts and Sciences : Psychology

Postural instability is a classical characteristic of cerebral palsy (CP), but it has not been examined in the during simultaneous supra-postural activity. It is important to study postural control in the context of other behaviors children perform when standing because recent work demonstrates that when motor tasks are made functionally more relevant, performance improves, even in individuals with movement pathology (Volman et al., 2001). If supra-postural tasks provide a functional context for postural control, children with CP might improve postural stability when performing supra-postural tasks.Thirty children with CP participated in this study. Their postural sway was quantified during performance of two different supra-postural manual tasks (a steadiness task involving keeping a pointer inside a target, and a task requiring balancing a marble inside a hollow tube), and compared to a control group (n = 30) of comparably aged, typically developing children. A baseline condition (no supra-postural task) was also included. Traditional measures of postural sway variability and non-linear quantification of patterns in the time-evolution of postural sway were analyzed using analyses of variance and appropriate simple-effects and post-hoc tests. I hypothesized supra-postural task performance would reduce postural sway variability in both typically developing and CP children. I also hypothesized the postural sway of children with CP would exhibit rigid, stereotypical behavior and a decrease in complexity, in accordance with a growing body of research on the loss of behavioral and physiological complexity accompanying dynamical diseases (West, 2006). I furthermore hypothesized that the latter difference would be attenuated during performance of the supra-postural tasks. The outcomes supported the hypotheses. Children with CP demonstrated changes in postural stability consistent with supra-postural task effects. The results were also consistent with the loss of complexi (open full item for complete abstract)

Committee: Michael Riley PhD (Committee Chair); Kevin Shockley PhD (Committee Member); Sarah Cummins-Sebree PhD (Committee Member); Laura Schmitt PT, PhD (Committee Member) Subjects: Biomedical Research; Health; Neurology; Occupational Psychology; Psychology; Rehabilitation; Therapy

MA, University of Cincinnati, 2005, Arts and Sciences : Psychology

Recent evidence suggests that the postural control system and the cognitive system interact when engaged concurrently. However, the literature is inconsistent with regard to whether cognitive activity degrades or facilitates postural control, and with regard to whether distinct types of cognitive activity differentially affect postural control. The aim of this project was to assess the effects of working memory tasks on postural control. Participants were instructed to perform simultaneously a posture task and a working memory task, which varied across trials along three dimensions: a) type of information (verbal and visual), b) working memory component (phonological loop, visual sketchpad and central executive), and c) cognitive process (encoding and rehearsal). Results showed a general tendency for postural sway to decrease during rehearsal and to increase during encoding of cognitive information, but these effects were not specific to the working memory component that was presumably engaged by the verbal and visual tasks.

Committee: Michael Riley (Advisor) Subjects: Psychology, Experimental

MA, University of Cincinnati, 2003, Arts and Sciences : Psychology

Postural instability is a primary symptom of advanced Parkinson's disease (PD). Falling, loss of mobility, and restriction of activity due to postural instability have a major influence on the health and quality of life of PD patients. Presently, clinical measurement of postural stability in PD is crude. Patient recovery to a sudden, backward pull of the shoulders by the physician (the retropulsion test) typically serves as an index of postural instability. The retropulsion test is subjective and there are presently no standards to govern its administration. In addition to the lack of sophistication in clinical measurement, little is known about factors that interact with postural instability to threaten balance for people with PD. The purpose of the present study was to employ static posturography (objective, quantitative measurements of naturally occurring postural sway obtained from a computerized biomechanics system called a force platform) to determine how visual perception and the attentional demands of a visuo-spatial cognitive task affected postural stability in PD. The results of the study indicated that the postural sway of PD patients in H-Y stage 3 (Hoehn & Yahr, 1967; H-Y stage 3 is a fairly advanced stage of PD at which balance and gait problems appear) was more variable than that of elderly, healthy controls. In addition, a time series technique called recurrence quantification analysis revealed that the spatiotemporal profile of postural sway for PD patients reflected greater recurrence (auto-correlation), determinism, mathematical stability, and complexity in the anterior-posterior sway direction. Recurrence was also higher (in the medial-lateral sway direction) with vision than without vision. No effects of the cognitive task were found. The results suggest that the novel combination of static posturography and RQA reliably differentiated PD patients from control participants.

Committee: Dr. Michael A. Riley (Advisor) Subjects:

MA, University of Cincinnati, 2001, Arts and Sciences : Psychology

The purpose of the present thesis was to investigate the relation between upright posture and perceptual performance. Some researchers have argued that the integration of multisensory perceptual stimulation, which is required for postural control, may draw on central processing capacity. From this perspective, performing cognitively demanding tasks should negatively influence postural control (i.e., induce higher levels of postural sway). This is because of competition for processing resources between the cognitive task and maintaining balance. An alternative theoretical view suggests that postural sway may be functionally related to performance on perceptual supra-postural tasks, independent of the effects of cognition. Three experiments were conducted in which the variability in postural sway was analyzed in the context of supra-postural goal variation. Experiment 1 focused on postural sway in response to performing a visually demanding signal detection task versus a mental arithmetic condition. The two tasks were equated in terms of overall subjective mental workload. Experiment 2 compared sway during performance of easy and hard mental arithmetic tasks. Experiment 3 controlled for a possible confound of vocalizing arithmetic responses in Experiment 1. There was significantly less sway when performing visual signal detection (relative to sway during mental arithmetic), but no significant differences in sway between the easy and hard arithmetic conditions. The results support the idea that postural sway is organized with reference to constraints imposed by the perceptual demands of supra-postural tasks, but not with reference to non-perceptual cognitive demand. Human factors design implications were discussed with respect to virtual reality and virtual environments.

Committee: Dr. Thomas Stoffregen (Advisor) Subjects: Psychology, Experimental

Doctor of Philosophy, University of Toledo, 2011, College of Health Sciences

Our primary purpose in this study was to compare the effects of wearing the five-toed socks with grippers alone (FSG), regular socks alone (RS), both five-toed socks and an ankle brace (FSGB), and both regular socks and an ankle brace (RSB) on dynamic postural control as measured with Time to Stabilization Resultant Vector (RVTTS) after landing from a jump in chronic ankle instability (CAI) and matched control subjects. The secondary purpose was to compare the effects of wearing FSG, RS, FSGB, and RSB on subjective measures concerning comfort, stability, and confidence in preventing the ankle from a potential injurious situation during the jump-landing procedure in CAI and matched control subjects. Forty eight subjects between the ages of 18 and 30 years old were recruited from the university community, and the subjects were separated into those with (n=24) and without unilateral CAI (n=24). RVTTS and subjective measures were recorded with jump-landing procedure. There was no significant difference in any of the outcome measures in RVTTS. The result of the subjective measurement revealed that, the regardless of the sock conditions, wearing an ankle brace improves comfort, stability, and confidence during a jump-landing procedure among CAI subjects. Future study should determine how enhanced foot gripping and plantar tactile sensation provided by the FSG plays a role in dynamic postural control among CAI subjects.

Committee: Phillip Gribble PhD (Committee Chair); Charles Armstrong PhD (Committee Member); Brian Pietrosimone PhD (Committee Member); Kate Pfile PhD (Committee Member); Michael Tevald PhD (Committee Member) Subjects: Biomechanics