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 中风等神经损伤后，功能活动能力通常会受到限制。行动能力下降的一个潜在原因是步态稳定性下降，中风后跌倒风险增加就证明了这一点。活动能力下降的第二个潜在原因是步行的能量消耗增加，再加上心血管能力下降，可能会导致限制活动的疲劳。该项目提出，中风后步态稳定性下降和能量消耗增加可部分归因于感觉运动整合的改变，如准确控制随意运动的能力下降所表明的。准确的运动控制需要能够产生预期的肌肉激活模式（驱动精度），并能够利用来自外围的反馈来感知运动身体部分的机械状态（感觉精度），这两种能力在中风后通常会降低。拟议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会影响稳定性和能量成本。该项目的第一个目标是确定控制精度降低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面步态稳定性可以被动地维持以响应小的扰动，但额面稳定性需要主动控制。保持横向稳定性的最简单的控制策略是选择适当的摆动腿的内侧脚放置位置，更多的外侧脚放置位置需要较少的精确控制。拟议的实验将测试控制精度降低是否可以解释中风后额面力学的变化。这些实验的主要预期结果是，为经历过中风的人提供增强的感觉反馈将恢复更典型的步态模式，这一发现具有明确的临床意义。该项目的第二个目标是量化有限的控制精度对中风后运动能量消耗增加的影响。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性，从而无需大量跖屈肌的工作即可实现强劲的推出。同样，利用肌腱弹性可以大大减少弹跳的能量需求，而与行走相比，该任务的简单性可以简化系统力学的量化。拟议的实验将量化以下因素对弹跳效率的影响：1）改变机械组织特性，特别是降低 肌腱僵硬； 2）肌肉将代谢能转化为机械能的效率变化； 3）无法利用感官反馈识别最佳运动模式。主要的预期结果是，中风后，患者将无法识别最能利用系统力学的运动模式。通过选择非最佳的运动模式，能量消耗将会增加。 公共卫生相关性： 每年，大约有 15,000 名美国退伍军人经历中风，估计急性和后续护理费用高达数亿美元。中风后，恢复或改善行走能力是患者的首要目标，但只有约一半的人能够恢复到典型的社区行走水平。由此导致的独立活动能力的下降与生活质量的下降密切相关。拟议的项目将研究中风后神经控制准确性的变化如何导致步态稳定性下降和行走能量消耗增加，这两个因素都会降低活动能力。这些结果将作为开发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。