Impact of Voluntary Muscle Activation on Stretch Reflex Excitability in Individuals With Hemiparetic Stroke

Frontiers in Neurology

卷:13

Julius P. A. Dewald¹  Netta Gurari²  Justin M. Drogos³  Jacqueline R. Patterson⁴ 

[1] Department of Biomedical Engineering, Northwestern University, Evanston, IL, United States;

[2] Department of Mechanical Engineering, Northwestern University, Evanston, IL, United States;

[3] Department of Physical Therapy and Human Movement Sciences, Northwestern University, Chicago, IL, United States;

[4] Department of Physiology, Northwestern University, Chicago, IL, United States;

[5] Northwestern University Interdepartmental Neuroscience, Northwestern University, Chicago, IL, United States;

关键词: stroke;    hypertonia;    spasticity;    motoneuron;    stretch reflex;    stretching;   

DOI  :  10.3389/fneur.2022.764650

来源: DOAJ

【 摘 要 】

ObjectiveTo characterize how, following a stretch-induced attenuation, volitional muscle activation impacts stretch reflex activity in individuals with stroke.MethodsA 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°.ResultsData from 15 participants indicated that the stretching sequence attenuated the flexion torque (p < 0.001) and resting sustained the attenuation (p = 1.000). Contrastingly, based on data from 14 participants, voluntary muscle activation increased the flexion torque (p < 0.001) to an initial pre-stretch torque magnitude (p = 1.000).ConclusionsStretch 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.SignificanceStretching 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.

【 授权许可】

Unknown