Hip Angle and Limb Load Affect Reflexes Post-Stroke

描述（由申请人提供）：中风后，步态通常表现为瘫痪肢体屈曲减少，并伴有后期站立和摆动期间膝关节伸展延长。这种运动模式归因于两个相互竞争的起源：屈肌激活不足和/或通过过度的四头肌活动引起的伸肌激活不当。有证据表明髋关节角度和肢体负荷感受器在调节步态后期站立阶段的肌肉活动中具有双重重要性。然而，中风后，传入信息的处理可能会被异常的下行命令中断，从而改变肌肉激活和运动模式。该提案的主要目标是表征髋关节角度传感器和负荷感受器在调节中风后激活模式中的重要性，以确定它们各自在导致异常步态中的作用。主要的假设是，从髋屈肌到膝伸肌的过度兴奋性异源性牵张反射在伸肌活动的时机错误中起着关键作用，从而在步态异常中起着关键作用。拟议的实验涉及到肌肉激活模式的仔细检查，以响应孤立的关节运动在被动条件下，以及在扰动行走。虽然适当的传入输入与肢体负荷和髋关节的位置被认为是必要的再训练中风后的“正常”行走模式，有没有定量的研究，探讨髋关节角度和肢体负荷在调节中风后的肌肉活动的作用。

DESCRIPTION (provided by applicant): Following stroke, gait is often characterized by reduced flexion of the paretic limb accompanied by prolonged knee extension during late stance and swing. This movement pattern has been attributed to two competing origins: inadequate flexor activation and/or inappropriate extensor activation via excessive quadriceps activity. Evidence has demonstrated the dual importance of hip angle and limb load receptors in modulating muscle activity during the late stance phase of gait. Following stroke, however, the processing of afferent information may be disrupted by abnormal descending commands, which alter muscle activation and movement patterns. The primary goal of this proposal is to characterize the importance of hip angle sensors and load receptors in modulating activation patterns post-stroke to determine their respective role in contributing to abnormal gait. The primary hypothesis is that hyperexcitable heteronymous stretch reflexes from hip flexors onto knee extensors play a critical role in the mistiming of extensor activity and thus in gait abnormalities. The proposed experiments involve a careful examination of muscle activation patterns in response to isolated joint movements during passive conditions as well as during perturbed walking. Although appropriate afferent inputs associated with limb load and hip position are thought to be necessary for retraining 'normal' walking patterns after stroke, there are no quantitative studies which examine the role of hip angle and limb load in modulating muscle activity after stroke.