Post-Stroke Contributors to Increased Energetic Cost and Decreased Gait Stability

中风后导致能量消耗增加和步态稳定性下降

• 批准号: 8277459
• 负责人: JESSE C. DEAN
• 金额: --
• 依托单位: RALPH H JOHNSON VA MEDICAL CENTER
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-10-01 至 2016-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8277459
• 关键词: Acute; Address; Affect; American; Award; Cardiovascular system; Caring; Clinical; Clinical Research; Communities; Development; Development Plans; Elasticity; Engineering; Esthesia; Fatigue; Feedback; Foundations; Freedom; Gait; Goals; Hip region structure; Individual; Intervention; Investigation; Lateral; Lead; Leg; Literature; Measures; Mechanics; Metabolic; Methods; Modeling; Motion; Movement; Muscle; Nervous System Trauma; Neurorehabilitation; Patients; Pattern; Persons; Physiology; Play; Population; Production; Property; Quality of life; Recovery; Rehabilitation therapy; Relative (related person); Research; Role; Series; Stroke; System; Techniques; Tendon structure; Testing; Tissues; Translating; Veterans; Walking; Work; achilles tendon; active control; base; career development; cost; design; direct application; disability; experience; fall risk; follow-up; foot; improved; improved functioning; kinematics; limb movement; mathematical model; motor control; muscle strength; neuroregulation; novel; post stroke; programs; research study; response; restoration; sensory feedback; skills; stroke rehabilitation

DESCRIPTION Following a neurological injury such as a stroke, functional mobility is often limited. One potential cause of reduced mobility is decreased gait stability, as evidenced by the increased risk of falls after a stroke. A second potential cause of reduced mobility is an increased energetic cost of walking, which in combination with reduced cardiovascular capacity can lead to activity-limiting fatigue. This project proposes that both the decreased gait stability and increased energetic cost seen after a stroke can be partially attributed to altered sensorimotor integration, as indicated by a decreased capacity to accurately control voluntary movement. Accurate motor control requires the ability to produce the intended muscle activation pattern (actuation accuracy) and the ability to sense the mechanical state of the moving body segment using feedback from the periphery (sensation accuracy), both abilities which are commonly reduced after a stroke. The proposed experiments will test whether reductions in control accuracy affect stability and energetic cost, based on the predictions of mechanical models. The first objective of the proposed project is to identify the effects of reduced control accuracy on lateral gait stability following a stroke. Simple mechanical models predict that sagittal plane gai stability can be maintained passively in response to small perturbations, but frontal plane stability requires active control. The simplest control strategy to maintain lateral stability is t choose an appropriate mediolateral foot placement of the swing leg, with more lateral foot placement requiring less accurate control. The proposed experiments will test whether decreased control accuracy explains altered frontal plane mechanics following a stroke. The primary anticipated result of these experiments is that delivering enhanced sensory feedback to persons who have experienced a stroke will restore a more typical gait pattern, a finding with clear clinical implications. The second objective of the proposed project is to quantify the contribution of limited control accuracy to the increased energetic cost of movement following a stroke. In typical gait, energetic economy is improved by storing and returning mechanical energy in the elastic Achilles tendon, allowing strong push-off without requiring large amounts of plantarflexor muscle work. Similarly, the energetic demand of bouncing can be substantially reduced by taking advantage of tendon elasticity, while the simplicity of the task in comparison to walking eases quantification of system mechanics. The proposed experiments will quantify the effect on bouncing efficiency of: 1) altered mechanical tissue properties, specifically reduced tendon stiffness; 2) changes in efficiency of the muscular conversion of metabolic energy to mechanical energy; 3) an inability to identify the optimal movement pattern using sensory feedback. The primary anticipated result is that following a stroke, patients will be unable to identify the pattern of movement that takes optimal advantage of system mechanics. By choosing a non-optimal movement pattern, energetic cost will be increased. PUBLIC HEALTH RELEVANCE: Every year, approximately 15,000 American veterans experience a stroke, with an estimated cost of acute and follow-up care in the hundreds of millions of dollars. Following a stroke, the restoration or improvement of walking is a high-ranking goal among patients, but only about half of the population is able to return to typical levels of community ambulation. The resultant decrease in independent mobility is strongly associated with a decline in quality of life. The proposed project will investigate how post-stroke changes in neural control accuracy contribute to decreases in gait stability and increases in the energetic cost of walking, both factors that ca reduce mobility. These results will serve as the basis for the development of novel gait rehabilitation techniques, which has the potential to increase the quality of life of thousands of veterans and save millions of dollars.

描述 在神经损伤（例如中风）之后，功能迁移率通常受到限制。步态稳定性降低的一个潜在原因是中风后跌倒的风险增加所证明的。迁移率降低的第二个潜在原因是步行的能量成本增加，结合心血管容量降低会导致限制活动疲劳。该项目提出，步态稳定性的降低和中风后看到的能量成本增加都可以部分归因于感觉运动的整合，这表明，准确控制自愿运动的能力降低了。准确的运动控制需要能够产生预期的肌肉激活模式（致动精度），并具有使用外围的反馈（感觉精度）感知移动身体部门机械状态的能力，这两种能力通常会降低。提出的实验将根据机械模型的预测来测试控制精度的降低是否影响稳定性和能量成本。拟议项目的第一个目标是确定降低控制精度对中风后横向步态稳定性的影响。简单的机械模型预测，矢状平面GAI稳定性可以响应小扰动而被动地维持，但是额叶平面的稳定性需要主动控制。保持侧向稳定性的最简单控制策略是选择适当的秋千腿中外侧脚放置，其横向脚部放置需要较少准确的控制。提出的实验将测试降低的控制精度是否解释了中风后额叶机械的改变。这些实验的主要预期结果是，向经历中风的人提供增强的感觉反馈将恢复更典型的步态模式，这一发现具有明显的临床意义。拟议项目的第二个目标是量化有限控制精度对中风后运动成本增加的贡献。在典型的步态中，通过在弹性跟腱中存储和返回机械能来改善能量经济，从而可以强大的推断，而无需大量的植物plantarflexor肌肉工作。同样，通过利用肌腱弹性，可以大大降低弹跳的能量需求，而与步行相比，任务的简单性可以轻松地量化系统力学的定量。提出的实验将量化对弹跳效率的影响：1）改变机械组织特性，特别降低 肌腱刚度； 2）代谢能向机械能的肌肉转化效率的变化； 3）无法使用感觉反馈来识别最佳运动模式。主要预期结果是，在中风之后，患者将无法识别具有系统力学最佳优势的运动模式。通过选择非最佳运动模式，将提高能量成本。 公共卫生相关性： 每年，大约15,000名美国退伍军人都会中风，估计急性和随访成本为数亿美元。中风后，步行的恢复或改进是患者的高级目标，但只有大约一半的人口能够恢复到典型的社区流动水平。独立流动性的结果降低与生活质量下降密切相关。拟议的项目将研究神经控制准确性的冲程后变化如何有助于步态稳定性的下降和步行能量成本的增加，这两个因素都会降低迁移率。这些结果将是发展新型步态康复技术的基础，该技术有可能提高数千名退伍军人的生活质量并节省数百万美元。