Journal article
Motor unit tracking using blind source separation filters and waveform cross-correlations: reliability under physiological and pharmacological conditions
Journal of Applied Physiology, Vol.135(2), pp.362-374
2023
PMID: 37410901
Abstract
Recent advancements in the analysis of high-density surface electromyography (HDsEMG) have enabled the identification, and tracking, of motor units (MUs) to study muscle activation. This study aimed to evaluate the reliability of MU tracking using two common methods: blind source separation filters and two-dimensional waveform cross-correlation. An experiment design was developed to assess physiological reliability and reliability for a drug intervention known to reduce the discharge rate of motoneurones (cyproheptadine). HDsEMG signals were recorded from tibialis anterior during isometric dorsiflexions to 10, 30, 50, and 70% of maximal voluntary contraction (MVC). MUs were matched within session (2.5 h) using the filter method, and between sessions (7 days) via the waveform method. Both tracking methods demonstrated similar reliability during physiological conditions [e.g., MU discharge: filter intraclass correlation coefficient (ICC): 10% of MVC = 0.76, to 70% of MVC = 0.86; waveform ICC: 10% of MVC = 0.78, to 70% of MVC = 0.91]. Although reliability slightly reduced after the pharmacological intervention, there were no discernible differences in tracking performance (e.g., MU discharge filter ICC: 10% of MVC = 0.73, to 70% of MVC = 0.75; waveform ICC: 10% of MVC = 0.84, to 70% of MVC = 0.85). The poorest reliability typically occurred at higher contraction intensities, which aligned with the greatest variability in MU characteristics. This study confirms that the tracking method may not impact the interpretation of MU data, provided that an appropriate experiment design is used. However, caution should be used when tracking MUs during higher-intensity isometric contractions.
Details
- Title
- Motor unit tracking using blind source separation filters and waveform cross-correlations: reliability under physiological and pharmacological conditions
- Authors
- Benjamin I Goodlich (Corresponding Author) - Griffith UniversityAlessandro Del Vecchio - Friedrich-Alexander-Universität Erlangen-NürnbergJustin J Kavanagh - Griffith University
- Publication details
- Journal of Applied Physiology, Vol.135(2), pp.362-374
- Publisher
- American Physiological Society
- Date published
- 2023
- DOI
- 10.1152/japplphysiol.00271.2023
- ISSN
- 1522-1601
- PMID
- 37410901
- Organisation Unit
- School of Health - Sports & Exercise Science
- Language
- English
- Record Identifier
- 991080582702621
- Output Type
- Journal article
Metrics
1 Record Views