The Motor Unit Recruitment Patterns in Stroke Show Different Characteristics Depending on the Phase

Abstract

Objective: The aim of this study was to clarify the characteristics of motor unit recruitment patterns in post-stroke at different phases。

Methods: A total of 16 subjects, 8 subacute and 8 chronic phase stroke patients, participated in this study. Wireless surface electromyography(sEMG) was attached to the biceps brachii on the unaffected and affected side. We measured maximum muscle force and performed visual tracking tasks. Then, we decomposed and detected the motor unit data from the sEMG signal using the decomposition algorithm. We calculated the motor unit recruitment range and motor unit recruitment threshold, and the motor unit firing rate was analyzed for phase factors and paralysis factors.

Results: The results suggest that the motor unit recruitment range and threshold were lower in the chronic phase than in the subacute phase. There were significant effects of the phase factors and no significant effect of the paralysis factors.

Conclusion: The motor unit recruitment patterns, in which small motor units act synchronously to control forces, indicated different characteristics between the subacute and chronic phases.