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: 8838208
• 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/8838208
• 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; Paresis; 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.

描述 在神经损伤如中风后，功能活动通常受到限制。活动性降低的一个潜在原因是步态稳定性降低，如中风后福尔斯风险增加所证明的。行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，可能会导致活动限制性疲劳。该项目提出，中风后步态稳定性降低和能量消耗增加都可以部分归因于感觉运动整合的改变，如准确控制自主运动的能力降低所示。精确的运动控制需要产生预期的肌肉激活模式的能力（致动准确性）和使用来自外周的反馈来感测运动身体节段的机械状态的能力（感觉准确性），这两种能力通常在中风后降低。根据机械模型的预测，拟议的实验将测试控制精度的降低是否会影响稳定性和能量成本。建议的项目的第一个目标是确定减少控制精度对中风后的横向步态稳定性的影响。简单的力学模型预测，矢状面的稳定性可以被动地维持以响应小的扰动，但额状面的稳定性需要主动控制。保持侧向稳定性的最简单的控制策略是选择摆动腿的适当的中外侧脚位置，更外侧的脚位置需要更少的精确控制。拟议的实验将测试是否降低控制精度解释改变额状面力学中风后。这些实验的主要预期结果是，向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。所提出的项目的第二个目标是量化的贡献有限的控制精度增加运动的能量成本后中风。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，从而允许强有力的蹬离而不需要大量的跖屈肌肌肉工作。类似地，弹跳的能量需求可以通过利用肌腱弹性而大大减少，而与行走相比，任务的简单性简化了系统力学的量化。所提出的实验将量化以下因素对弹跳效率的影响：1）改变的机械组织特性，特别是减少的机械组织特性。 肌腱刚度; 2）肌肉将代谢能转化为机械能的效率的变化; 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，中风后，患者将无法识别最佳利用系统力学的运动模式。通过选择非最佳运动模式，能量成本将增加。