Bibliographic Details
| Title: |
Characterizing motor unit firing rates in the human erector spinae. |
| Authors: |
Travis PJ; School of Kinesiology, Faculty of Health Sciences, Western University, London, Ontario, Canada., Fanous J; School of Kinesiology, Faculty of Health Sciences, Western University, London, Ontario, Canada., Rice CL; School of Kinesiology, Faculty of Health Sciences, Western University, London, Ontario, Canada.; Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, Western University, London, Ontario, Canada. |
| Source: |
Journal of applied physiology (Bethesda, Md. : 1985) [J Appl Physiol (1985)] 2026 May 01; Vol. 140 (5), pp. 1152-1158. Date of Electronic Publication: 2026 Mar 26. |
| Publication Type: |
Journal Article |
| Language: |
English |
| Journal Info: |
Publisher: American Physiological Society Country of Publication: United States NLM ID: 8502536 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1522-1601 (Electronic) Linking ISSN: 01617567 NLM ISO Abbreviation: J Appl Physiol (1985) Subsets: MEDLINE |
| Imprint Name(s): |
Original Publication: Bethesda, MD : American Physiological Society, c1985- |
| MeSH Terms: |
Motor Neurons*/physiology , Muscle, Skeletal*/physiology , Recruitment, Neurophysiological*/physiology, Electromyography/methods ; Isometric Contraction/physiology ; Muscle Contraction/physiology ; Transcranial Magnetic Stimulation/methods ; Posture/physiology ; Humans ; Male ; Adult ; Female ; Torque ; Young Adult |
| Abstract: |
Muscles of the erector spinae (ES) are vital for maintaining posture, yet their motor unit firing rates (MUFRs) are not well described compared with many limb muscles. Therefore, this study aimed to characterize ES MUFRs across a full range of contractile intensities, including at maximum voluntary contraction (MVC). Intramuscular electromyography was used to record motor unit activity from the ES muscles (left and right sides) in 10 healthy participants. Data were collected during isometric trunk extension at intensities from 10% to 100% MVC. Voluntary activation was assessed using transcranial magnetic stimulation, and mean values were >88%. Torque-firing rate relationships were analyzed to identify rate-coding patterns and potential side-to-side differences at each intensity. Contrary to our hypothesis, the ES exhibited rate-coding patterns similar to limb muscles reported previously. A linear relationship was observed between torque and MUFR, with mean rates increasing from ∼10 Hz at 10% MVC to ∼34 Hz at 100% MVC. A significant side-related effect was found at higher intensities, in which the nondominant side demonstrated higher MUFRs compared with the dominant side. These findings indicate that whereas the ES serves a unique postural role, rate-coding strategies are comparable to those of the appendicular musculature. The observed side-to-side differences at high intensities may reflect functional asymmetries in trunk stabilization.NEW & NOTEWORTHY This study provides a comprehensive characterization of the human erector spinae motor unit firing rates across a full range of intensities, including maximal effort with assessment of voluntary activation during isometric back extensions. Contrary to neural circuitry differences and postural function, the erector spinae rate codes similar to limb muscles. Furthermore, we identified significant side-to-side differences in firing rates at higher intensities, indicating a neural compensation to maintain spinal stability. |
| Grant Information: |
18079 Natural Sciences and Engineering Research Council of Canada (NSERC) |
| Contributed Indexing: |
Keywords: back extension; bilateral activation; electromyography; force dynamometry; motor control |
| Entry Date(s): |
Date Created: 20260326 Date Completed: 20260713 Latest Revision: 20260713 |
| Update Code: |
20260714 |
| DOI: |
10.1152/japplphysiol.00095.2026 |
| PMID: |
41886304 |
| Database: |
MEDLINE |