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Impaired Firing Behavior of Individually Tracked Paretic Motor Units During Fatiguing Contractions of the Dorsiflexors and Functional Implications Post Stroke. Front Neurol 2020;11:540893

Date

11/17/2020

Pubmed ID

33192970

Pubmed Central ID

PMC7658471

DOI

10.3389/fneur.2020.540893

Scopus ID

2-s2.0-85095993454 (requires institutional sign-in at Scopus site)   5 Citations

Abstract

Introduction: This study quantified stroke-related changes in the following: (1) the averaged discharge rate of motor units (individually tracked and untracked) identified from high-density electromyography (HD-EMG) recordings, (2) global muscle EMG properties of the dorsiflexors during a fatiguing contraction, and the relationship between task endurance and measures of leg function. Methods: Ten individuals with chronic stroke performed a sustained sub-maximal, isometric, fatiguing dorsiflexion contraction in paretic and non-paretic legs. Motor-unit firing behavior, task duration, maximal voluntary contraction strength (MVC), and clinical measures of leg function were obtained. Results: Compared to the non-paretic leg, the paretic leg task duration was shorter, and there was a larger exercise-related reduction in motor unit global rates, individually tracked discharge rates, and overall magnitude of EMG. Task duration of the paretic leg was more predictive of walking speed and lower extremity Fugl-Meyer scores compared to the non-paretic leg. Discussion: Paretic leg muscle fatigability is increased post stroke. It is characterized by impaired rate coding and recruitment and relates to measures of motor function.

Author List

Negro F, Bathon KE, Nguyen JN, Bannon CG, Orizio C, Hunter SK, Hyngstrom AS

Author

Allison Hyngstrom PhD Associate Professor in the Physical Therapy department at Marquette University