Impaired Firing Behavior of Individually Tracked Paretic Motor Units During Fatiguing Contractions of the Dorsiflexors and Functional Implications Post Stroke

Authors

Francesco Negro, University of BresciaFollow
Kathleen Bathon, University of Health Sciences
Jennifer Nguyen, Medical College of WisconsinFollow
Cassidy Bannon, University of Health Sciences
Claudio Orizio, University of Brescia
Sandra Hunter, Marquette UniversityFollow
Allison Hyngstrom, Marquette UniversityFollow

Document Type

Article

Language

eng

Publication Date

10-2020

Publisher

Frontiers Media S.A.

Source Publication

Frontiers in Neurology

Source ISSN

1664-2295

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.

Comments

Published version. Frontiers in Neurology, Vol. 11, (October 2020). DOI. © 2020 Frontiers Media S.A. Used with permission.

Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

Recommended Citation

Negro, Francesco; Bathon, Kathleen; Nguyen, Jennifer; Bannon, Cassidy; Orizio, Claudio; Hunter, Sandra; and Hyngstrom, Allison, "Impaired Firing Behavior of Individually Tracked Paretic Motor Units During Fatiguing Contractions of the Dorsiflexors and Functional Implications Post Stroke" (2020). Exercise Science Faculty Research and Publications. 186.
https://epublications.marquette.edu/exsci_fac/186