Voluntary and magnetically evoked muscle contraction protocol in males with Duchenne muscular dystrophy: Safety, feasibility, reliability, and validity

Joyceann P. Trost, Mo Chen, Molly M. Stark, James S. Hodges, Sara Richter, Angus Lindsay, Gordon L. Warren, Dawn A. Lowe, Teresa J. Kimberley

Research output: Contribution to journalArticlepeer-review

Abstract

INTRODUCTION/AIMS: Clinical trials addressing treatments for Duchenne muscular dystrophy (DMD) require reliable and valid measurement of muscle contractile function across all disease severity levels. In this work we aimed to evaluate a protocol combining voluntary and evoked contractions to measure strength and excitability of wrist extensor muscles for safety, feasibility, reliability, and discriminant validity between males with DMD and controls.

METHODS: Wrist extensor muscle strength and excitability were assessed in males with DMD (N = 10; mean ± standard deviation: 15.4 ± 5.9 years of age), using the Brooke Upper Extremity Rating Scale (scored 1-6), and age-matched healthy male controls (N = 15; 15.5 ± 5.0 years of age). Torque and electromyographic (EMG) measurements were analyzed under maximum voluntary and stimulated conditions at two visits.

RESULTS: A protocol of multiple maximal voluntary contractions (MVCs) and evoked twitch contractions was feasible and safe, with 96% of the participants completing the protocol and having a less than 7% strength decrement on either measure for both DMD patients and controls (P ≥ .074). Reliability was excellent for voluntary and evoked measurements of torque and EMG (intraclass correlation coefficient [ICC] over 0.90 and over 0.85 within and between visits, respectively). Torque, EMG, and timing of twitch-onset measurements discriminated between DMD and controls (P < .001). Twitch contraction time did not differ significantly between groups (P = .10).

DISCUSSION: Findings from this study show that the protocol is a safe, feasible, reliable, and a valid method to measure strength and excitability of wrist extensors in males with DMD.

Original languageEnglish (US)
Pages (from-to)190-198
Number of pages9
JournalMuscle and Nerve
Volume64
Issue number2
Early online dateMay 11 2021
DOIs
StatePublished - Aug 2021

Bibliographical note

Funding Information:
Gillette Children's Foundation; University of Minnesota Bob Allison Ataxia Research Center Grant Funding information

Publisher Copyright:
© 2021 Wiley Periodicals LLC

Keywords

  • dystrophin
  • magnetic stimulation
  • outcome measures
  • surface electromyography
  • torque

PubMed: MeSH publication types

  • Journal Article
  • Research Support, Non-U.S. Gov't

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