Academic Journal
Comparison of human motor unit firing rates in the vastus intermedius and vastus lateralis during isometric knee extension.
| Τίτλος: | Comparison of human motor unit firing rates in the vastus intermedius and vastus lateralis during isometric knee extension. |
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| Συγγραφείς: | Fanous J; School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, ON, Canada., Zero AM; School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, ON, Canada.; Department of Human Health Sciences, College of Biological Sciences, University of Guelph, Guelph, ON, Canada., Rice CL; School of Kinesiology, Faculty of Health Sciences, The University of Western Ontario, London, ON, Canada. crice@uwo.ca.; Department of Anatomy and Cell Biology, Schulich School of Medicine and Dentistry, The University of Western Ontario, London, ON, Canada. crice@uwo.ca. |
| Πηγή: | European journal of applied physiology [Eur J Appl Physiol] 2026 Jun; Vol. 126 (6), pp. 3429-3436. Date of Electronic Publication: 2026 Feb 25. |
| Τύπος έκδοσης: | Journal Article; Comparative Study |
| Γλώσσα: | English |
| Στοιχεία περιοδικού: | Publisher: Springer-Verlag Country of Publication: Germany NLM ID: 100954790 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1439-6327 (Electronic) Linking ISSN: 14396319 NLM ISO Abbreviation: Eur J Appl Physiol Subsets: MEDLINE |
| Imprint Name(s): | Original Publication: Berlin ; New York : Springer-Verlag, c2000- |
| Ιατρικοί όροι (MeSH): | Quadriceps Muscle*/physiology , Isometric Contraction*/physiology , Motor Neurons*/physiology , Knee*/physiology , Knee Joint*/physiology , Recruitment, Neurophysiological*, Electromyography/methods ; Humans ; Female ; Male ; Adult ; Action Potentials ; Young Adult ; Torque |
| Περίληψη: | PURPOSE: Neuromuscular properties have been well-studied in three of the four muscles of the quadriceps femoris. However, lack of accessibility of the vastus intermedius (VI) due to its deep location has precluded comprehensive insight on motor unit (MU) properties. Thus, the purpose here was to compare the MU firing rates of the VI and vastus lateralis (VL). METHODS: In ten young participants (3 females), ultrasound-guided intramuscular tungsten microelectrodes were used to record MU firing rates from the VI and VL during non-fatiguing contractions at four intensities, including during maximal efforts. RESULTS: Maximal knee extension torque was 518 ± 113 N with voluntary activation of over 90%. A total of 2741 MU trains were sampled with equal numbers from both muscles. There was a linear relationship between contractile intensity and mean MU firing rate in both the VI and VL (r = 0.79 and 0.81; P < 0.001), and rates ranged from ~ 8 Hz at 10% to ~ 27 Hz at maximum with no difference between the two muscles (P = 0.45) at any force level (P = 0.08). CONCLUSION: Despite, differences in anatomical and muscular architecture allowing for varying contributions to knee extension, MU firing rates were similar between the VI and VL. This indicates at the motor unit level that fundamental neural activation strategies between the two larger torque generating muscles of the quadriceps may be similar based on mean MU firing rates. Any variation in the relative contributions to knee extensor torque from these synergists may be governed more by biomechanical factors rather than apparent motor unit firing rate. |
| Competing Interests: | Declarations. Conflict of interest: The authors declare no conflict of interest. |
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| Grant Information: | 18079 Natural Sciences and Engineering Research Council of Canada |
| Contributed Indexing: | Keywords: Deep muscles; Discharge rate; Neuromuscular control; Quadriceps femoris; Synergistic control |
| Entry Date(s): | Date Created: 20260225 Date Completed: 20260627 Latest Revision: 20260627 |
| Update Code: | 20260628 |
| DOI: | 10.1007/s00421-026-06165-1 |
| PMID: | 41739163 |
| Βάση Δεδομένων: | MEDLINE |
| ISSN: | 1439-6327 |
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| DOI: | 10.1007/s00421-026-06165-1 |