Thesis (Ph.D.)--University of Central Florida, 2009. / Adviser: Pamela McCauley Bush. Includes bibliographical references (p. 149-159).

Falling during walking leads to millions of emergency room visits every year for all age groups and is a significant medical concern. While gait training has shown some promise for fall prevention, we know relatively little about how humans maintain stability, how we can quantify it and how we can use this knowledge to increase the success of fall prevention training. In this dissertation, I studied how human stability responds to continuous, small magnitude perturbations and to voluntary changes in gait characteristics by examining movement variability and long-term and instantaneous dynamic stability. In the first set of experiments, participants were exposed to continuous, pseudo-random external perturbations of the visual field and support surface in a Computer Assisted Rehabilitation ENvironment (CAREN). Participants exhibited increased step widths, shorter step lengths and increased step variability, orbital and short-term local instability. Despite this, mean instantaneous lateral stability remained approximately constant. In the second set of experiments, participants voluntarily adopted changes in their step widths and step lengths. Wider steps were associated with increased step width variability, decreased nonlinear stability, decreased anterior-posterior margins of stability and increased instantaneous lateral stability. Shorter steps were associated with decreased short-term and orbital stability but did not affect mean instantaneous stability. When instantaneous stability was examined between steps, as opposed to as an average over many steps, results from both studies indicated a relationship between each step’s stability and the stability of the immediately preceding step. From these studies, we now know that unpredictable, continuous perturbations during human walking applied in a given direction can be used to elicit predictable responses in motion variability and stability in that same direction. We know that the type of stability examined can influence the conclusions drawn about an individual’s stability during perturbed walking. For example, an individual’s variability may indicate increased risk of falling while he or she simultaneously demonstrates increased orbital stability and instantaneous lateral stability. A challenge faced in this area of research will be to understand how quantitative measures of stability relate to how we perceive our stability. / text

The purpose of this thesis was to investigate the influence of postural anxiety on the capacity for Flexible Resource Allocation (FRA) among younger (YA) and older adults (OA). Two experiments were conducted to explore (a) the influence of heightened postural anxiety on the flexible allocation of attention among OA and (b) the influence of concurrent postural challenge and postural anxiety on FRA among YA. Participants performed a postural task concurrently to a cognitive task according to three instructional sets directing task priority. Experiment one revealed that FRA was compromised among OA during circumstances of heightened anxiety. This capacity however, remained available among YA. Therefore, for the second experiment I varied the support surface to explore whether the capacity for FRA could be sustained when posture was challenged beyond static stance. Results indicated that YA altered cognitive task performance according to instructional set without compromising postural stability. These findings suggest that even when posture is challenged during heightened postural anxiety, YA maintain the capacity to automatically allocate attention to a postural task while performing a secondary task. Conversely, it seems that heightened postural anxiety strengthens the attentional bias to posture and subsequently compromises FRA among OA. Overall, results from this thesis suggest that the capacity for FRA is age and situation dependent. / xi, 107 leaves : ill. ; 29 cm

The effect of anxiety on motor learning during a balance relevant task was investigated. Twenty participants (mean age 22.0 ± 2.7 years) were randomly divided into groups that completed the task whilst standing directly on the platform or on 9cm high pedestals, thus constructing Non-Anxious (NA) or Anxious (A) environments. Participants trained for 36 trials in a continuous, pseudo-random oscillating balance task consisting of pseudo-random amplitude translation at 0.5Hz for 45 seconds each on Day 1 and returned for Retention and Transfer tests on Day 2. Motor performance was impaired by training in an anxious environment and this effect persisted across retesting in both non-anxious and anxious environments. Anxiety also tended to further impair transfer of motor performance improvements to a non-anxious environment. These findings have implications for the success of balance training programs in patients who are anxious or afraid of falling. / ix, 103 leaves : ill. ; 29 cm

Thesis (PhD)--University of South Australia, 1996

Thesis (Ph. D.)--University of Oregon, 2004. / Includes bibliographical references (leaves 135-143). Also available online (PDF file) by a subscription to the set or by purchasing the individual file.

Thesis (Ph. D.)--University of Oregon, 2004. / Includes bibliographical references (leaves 135-143).

One in three American older adults fall every year, making falls the leading cause of nonfatal injury treated in the emergency department (Centers for Disease Control and Prevention [CDC], 2013). Fall-related injuries cost the United States healthcare system nearly $30 billion a year and result in 27,000 deaths per year (Burns, Stevens, & Lee, 2016). The risk of falls increases with age, occurring more often in women than man. Age-related muscle weakness and functional decline contribute to fall risk. Age-related changes in neuroendocrine hormone production and shifts in circadian rhythms promote sleep disorders, affecting nearly two-thirds of older adults. Poor sleep quality over time leads to drowsiness and impaired attention span and judgment. The purpose of this secondary analysis of a previously collected data set was to describe the relationships among frailty, subjective sleep quality, and falls in community-dwelling older adults. This secondary analysis also sought to determine the extent to which frailty and subjective sleep quality predict risk of future falls among community-dwelling older adults. Correlational analyses were performed to determine the nature and significance of the relationship between sleep quality and falls, frailty and falls, and sleep quality and frailty. A multiple regression analysis was performed to determine if sleep quality and frailty combined could predict falls. Frailty was found to account for a small variance in fall risk. However, sleep quality was not significantly related to falls nor was sleep quality predictive of falls. Risk for falls should be assessed at every clinical encounter and efforts to promote restful sleep should be addressed at least annually to reduce the risks of falls, functional decline, and sleep disorders among older adults in the community. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

跌倒和肌肉減少症是威脅老年人身體健康和生命安全的兩個重要問題。肌肉減少症所致的肌肉力量減弱和平衡能力下降是導致老年人跌倒的最主要原因。老年人跌倒最普遍和最嚴重的後果是脆性骨折。跌倒所致的脆性骨折是常見老年病，同時也是導致老年人生活品質下降和死亡的最主要原因之一。高頻低幅振動(LMHFV)是一種非侵入性生物物理干預手段，通過給予全身物理震動刺激，可有效提高肌肉功能和改善骨質。由此推測高頻低幅振動治療有望應用於預防跌倒/骨折及延緩肌肉減少。 / 本研究的目的在於，採用臨床隨機對照研究方法，通過對社區老年人進行高頻低幅振動治療，探索高頻低幅振動治療在預防跌倒/骨折、降低骨折發生率以及延緩肌肉量下降的作用。本研究假設高頻低幅振動治療可有效提高肌肉力量和改善骨質，從而降低骨折風險、跌倒率以及骨折發生率。本研究將分成兩部分進行以驗證此假說。 / 第一部分研究中，710名60歲或以上的社區老年人按社區中心為單位隨機分成振動治療組和對照組。振動治療組給予35Hz，0.3g的振動治療，並以每天20分鐘，每週5 天，持續18 個月；對照組則如常生活而不予振動治療。18個月治療過程中，振動治療組的跌倒率低於對照組46% (p=0.001)。同時，治療組的在平衡力測試中的反應時間、移動速度，和最遠移動距離也都有明顯改善 (所有指標 p<0.001）。在高頻低幅振動治療停止一年後，振動治療組的主導腿和非主導腿肌肉力量仍高於接受振動治療前 (p=0.029, p=0.002)。在平衡力測試中，治療組的反應時間、移動速度以及最遠移動距離也明顯優於對照組 (p=0.001，p=0.014，p=0.007)。在停止治療的一年期間，兩組受試者的肌肉力量，平衡能力以及生活品質均有下降的趨勢，但兩組的下降率並無明顯的差異。 / 第二部分的設計是基於第一部分的研究成果，目的在於更深入研究高頻低幅振動治療對肌肉功能、肌肉量以及肌肉質素的影響。60名社區老人隨機分成對照組和振動治療組。振動治療組給予35Hz，0.3g的高頻低幅振動治療，並以每天20分鐘，每週5天，持續9個月; 對照組則如常生活而不予振動治療。9個月後，治療組的主導腿和非主導腿的肌肉力量明顯高於對照組 (p<0.001，p=0.003)。在用以評估肌肉力量以及平衡力的計時起立坐下測試中，振動治療組用以完成連串起立及坐下動作的時間明顯低於對照組 (p=0.009)。振動治療組的下肢功能尺度問卷評估結果也明顯優於對照組 (p=0.002)。雖然兩組間的身體成份及肌電圖測試結果並無明顯差異，但治療組的肌肉量和肌電圖平均頻率均有上升的趨勢。而且，在兩部分實驗中，受試者對高頻低幅振動治療均有良好的耐受性，目前並沒有發現對受試者身體產生不利影響。因此，高頻低幅振動治療可安全地應用於社區老年人。 / 總括而言研究結果證明高頻低幅振動治療可明顯降低老年人跌倒發生率。9至18個月的振動治療可明顯改善老年人下肢功能和平衡力。在完成為期18個月高頻低幅振動治療後的1年，肌肉功能仍高於對照組，表明高頻低幅振動治療具有長期療效。因此，高頻低幅振動治療應在社區推廣作為老年人跌倒的預防方案之一。 / Fall and sarcopenia are two major problems among elderly. Poor muscle strength and balancing ability resulted from sarcopenia are the major causes of fall incidences. Fragility fracture is one of the most common and serious consequences of falls, which accounts for most of the deaths, as well as morbidity and poor quality of life. Low magnitude high frequency vibration (LMHFV) treatment is a non-invasive biophysical modality to provide a whole-body mechanical stimulation, which was previously shown to improve muscle performance and bone quality implying the potential application for fall/fracture prevention and reducing muscle loss. / The objectives of this study were to conduct prospective randomized controlled clinical trials to investigate the effect of LMHFV treatment on fall/fracture prevention, fracture risks and muscle loss among community elderly. It was hypothesized that LMHFV treatment could enhance muscle performance and bone quality, thus reducing the fracture risks, fall incidence and fracture rate. Two parts of studies were designed to testify the hypotheses. / In the Part I study, a total of 710 community elderly who were aged 60 years or above were recruited and randomized into vibration or control group on center-basis. The subjects in vibration group received LMHFV treatment (35Hz, 0.3g) 20min/day and 5days/week for 18 months, while control group remained sedentary. During the 18-month study period, the vibration group had reported 46% lower fall incidence rate when compared with control group (p=0.001). Significant improvements were found in reaction time, movement velocity and maximum excursion of balancing ability assessment, and also the quadriceps muscle strength (p<0.001 to all). After ceasing the LMHFV for 1 year, the muscle strength of dominant and non-dominant legs in vibration group were still significantly better than the baseline assessed before intervention (p=0.029 and 0.002 respectively), as compared with the control. In balancing ability test, the reaction time, movement velocity and maximum excursion of vibration group also remained significantly improved, as compared with the control group (p=0.001, 0.014 and 0.007 respectively). During the 1 year post-intervention period, both groups had shown a decreasing trend of muscle strength, balancing ability and quality of life but the rate of changes were not significantly different between two groups. / With reference to the results of Part I study, the Part II study was designed to investigate further the effects of LMHFV on muscle performance, mass and quality. 60 community elderly were recruited and randomized into either vibration or control group. Vibration group subjects received LMHFV treatment (35Hz, 0.3g) 20min/day, 5days/week for 9 months, while control group remained sedentary. Significant enhancement of dominant and non-dominant leg muscle strength was observed in the vibration group after 9 months LMHFV (p<0.001 and =0.003 respectively). In the chair rising test assessing muscle power and balancing ability, vibration group showed significantly shorter time needed for sit-to-stand cycles than the control (p=0.009). Significant increase of the lower extremity functional scale was also observed in the vibration group (p=0.002). No significant findings were found in the body composition and vibromyography (VMG) assessment, however, a trend of increasing lean mass and VMG mean frequency were observed. Also, minimal adverse effects were documented in both parts of study; all subjects were well-tolerated for LMHFV treatment. LMHFV is therefore safe and applicable to elderly in the community setting. / LMHFV was demonstrated to reduce fall incidences significantly. Significant effects on improving lower limbs function and balancing ability were observed as early as 9 months after treatment. Enhancement of muscle performance still remained significant 1 year after completion of 18-month LMHFV treatment, indicating strong residual effects of LMHFV. Use of LMHFV in the community as an effective fall prevention program is recommended. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Li, Chi Yu. / Thesis (Ph.D.) Chinese University of Hong Kong, 2014. / Includes bibliographical references (leaves 154-167). / Abstracts also in Chinese.

Chan Cheung Shing. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (leaves 88-90). / Abstracts in English and Chinese. / Abstract --- p.ii / Acknowledgements --- p.iv / Table of Contents --- p.v / List of Figures --- p.viii / List of Tables --- p.xii / Abbreviations and Notations --- p.xiii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Background and Objective --- p.1 / Chapter 1.2 --- Contribution --- p.4 / Chapter 1.3 --- Thesis Outline --- p.5 / Chapter Chapter 2 --- System Architecture --- p.6 / Chapter 2.1 --- Conceptual Design --- p.6 / Chapter 2.2 --- Sensing Device and Fall-Detection Algorithm --- p.7 / Chapter 2.3 --- Mechanical Part --- p.10 / Chapter Chapter 3 --- Mechanical Design --- p.11 / Chapter 3.1 --- Similar Products --- p.11 / Chapter 3.1.1 --- Airbag Restraining Systems in Automobiles --- p.11 / Chapter 3.1.2 --- Airbag Jackets for Motorcycle and House Riders --- p.12 / Chapter 3.2 --- Mechanism adopted --- p.12 / Chapter 3.2.1 --- Time Requirement of Inflator --- p.12 / Chapter 3.2.2 --- Mechanism and Design --- p.13 / Chapter 3.2.3 --- Actuator --- p.14 / Chapter 3.2.4 --- Punch --- p.15 / Chapter 3.2.5 --- Airbags --- p.18 / Chapter 3.2.6 --- Other Mechanisms Tried --- p.19 / Chapter 3.3 --- Prototype --- p.21 / Chapter 3.3.1 --- Implementation --- p.21 / Chapter 3.3.2 --- Demonstration --- p.23 / Chapter Chapter 4 --- Inflation Estimation --- p.25 / Chapter 4.1 --- Theory and Model --- p.25 / Chapter 4.2 --- Validation of Model --- p.28 / Chapter 4.2.1 --- Testing Equipment --- p.28 / Chapter 4.2.2 --- Preprocessing of Pressure Sensor Outputs --- p.28 / Chapter 4.2.3 --- Validation for Basic Equations --- p.29 / Chapter 4.2.4 --- Adjustment of Discharge Coefficients --- p.36 / Chapter 4.2.5 --- Validation for Discharging to a Fixed Volume --- p.40 / Chapter 4.2.6 --- Estimation of the Size of Airbag's Leakage Hole --- p.45 / Chapter 4.2.7 --- Validation for Discharging to an Airbag --- p.47 / Chapter 4.2.8 --- Time Delay due to Addition of a Pipe --- p.52 / Chapter 4.3 --- Summary of Experiments --- p.53 / Chapter 4.4 --- Limitation of Model --- p.54 / Chapter 4.5 --- Prediction of Inflation Time and Airbag Pressure --- p.55 / Chapter 4.5.1 --- Effects of Orifice Size and Vent Size on Airbag Pressure and Volume --- p.55 / Chapter Chapter 5 --- Force Attenuation Estimation --- p.58 / Chapter 5.1 --- Theory and Model --- p.58 / Chapter 5.1.1 --- Kelvin-Voigt Model --- p.59 / Chapter 5.1.2 --- Standard Linear Solid Support Model --- p.59 / Chapter 5.2 --- Simple Testing for Validation --- p.61 / Chapter 5.3 --- Summary of Experiment --- p.64 / Chapter 5.4 --- Estimation --- p.64 / Chapter 5.4.1 --- Force Attenuation Ability of Prototype --- p.64 / Chapter 5.4.2 --- Minimum Airbag Volume and Pressure Required to Reduce the Force --- p.65 / Chapter Chapter 6 --- Future Work --- p.66 / Chapter 6.1 --- Impact Test for Airbag System --- p.66 / Chapter 6.2 --- The Effective Mass of the Target User --- p.67 / Chapter 6.3 --- The Motion Data Collection --- p.68 / Chapter 6.4 --- Modification in the Inflator --- p.69 / Chapter Chapter 7 --- Conclusion --- p.70 / Appendix A Review of Basic Thermodynamics and Fluid Dynamics --- p.72 / Chapter A.1 --- Thermodynamics --- p.72 / Chapter A.2 --- Fluid Mechanics: Incompressible and Compressible Flow --- p.75 / Appendix B Derivation of Equations --- p.77 / Chapter B.1 --- Mass Flow Rate Equations --- p.77 / Chapter B.2 --- Relationship between Rate of Changes of Airbag Pressure and Volume --- p.80 / Chapter B.3 --- Pressure Change of Compressed Gas Cylinder --- p.82 / Chapter B.4 --- Dominating Factors in the Mass Flow Rate Equation --- p.83 / Appendix C Dimensions of Inflator --- p.85 / Appendix D Experimental Data --- p.86