Patterson Jacqueline R, Dewald Julius P A, Drogos Justin M, Gurari Netta
Department of Physical Therapy and Human Movement Sciences, Northwestern University, Chicago, IL, United States.
Northwestern University Interdepartmental Neuroscience, Northwestern University, Chicago, IL, United States.
Front Neurol. 2022 Mar 8;13:764650. doi: 10.3389/fneur.2022.764650. eCollection 2022.
To characterize how, following a stretch-induced attenuation, volitional muscle activation impacts stretch reflex activity in individuals with stroke.
A robotic device rotated the paretic elbow of individuals with hemiparetic stroke from 70° to 150°, and then back to 70° elbow flexion at an angular speed of 120°/s. This stretching sequence was repeated 20 times. Subsequently, participants volitionally activated their elbow musculature or rested. Finally, the stretching sequence was repeated another 20 times. The flexors' stretch reflex activity was quantified as the net torque measured at 135°.
Data from 15 participants indicated that the stretching sequence attenuated the flexion torque ( < 0.001) and resting sustained the attenuation ( = 1.000). Contrastingly, based on data from 14 participants, voluntary muscle activation increased the flexion torque ( < 0.001) to an initial pre-stretch torque magnitude ( = 1.000).
Stretch reflex attenuation induced by repeated fast stretches may be nullified when individuals post-stroke volitionally activate their muscles. In contrast, resting may enable a sustained reflex attenuation if the individual remains relaxed.
Stretching is commonly implemented to reduce hyperactive stretch reflexes following a stroke. These findings suggest that stretch reflex accommodation arising from repeated fast stretching may be reversed once an individual volitionally moves their paretic arm.
描述在拉伸诱导的衰减之后，意志性肌肉激活如何影响中风患者的牵张反射活动。
一个机器人装置以120°/秒的角速度将偏瘫性中风患者的患侧肘部从70°旋转到150°，然后再回到70°肘部屈曲。这个拉伸序列重复20次。随后，参与者意志性地激活他们的肘部肌肉组织或休息。最后，拉伸序列再重复20次。屈肌的牵张反射活动被量化为在135°处测量的净扭矩。
15名参与者的数据表明，拉伸序列减弱了屈曲扭矩（<0.001），休息使这种衰减持续存在（=1.000）。相反，根据14名参与者的数据，意志性肌肉激活增加了屈曲扭矩（<0.001）至初始预拉伸扭矩大小（=1.000）。
中风后个体意志性激活其肌肉时，重复快速拉伸引起的牵张反射衰减可能会被消除。相比之下，如果个体保持放松，休息可能会使反射衰减持续。
拉伸通常用于减少中风后的过度活跃的牵张反射。这些发现表明，一旦个体意志性地移动其患侧手臂，重复快速拉伸引起的牵张反射适应可能会被逆转。
