Greater motor unit discharge rate during rapid contractions in chronically strength-trained individuals
Škarabot J, Casolo A, Balshaw TG, Maeo S, Lanza MB, Holobar A, Farina D, Folland JP, Del Vecchio A (2024)
Publication Type: Journal article
Publication year: 2024
Journal
Book Volume: 132
Pages Range: 1896-1906
Journal Issue: 6
Abstract
Though similar motor unit (MU) discharge properties have been observed during slow sustained contractions between chronically strength-trained (ST) and untrained (UT) individuals, it is currently unknown whether differences between these groups exist for when maximal in vivo MU discharge rate is assessed during rapid, maximal rate of force development (RFD) contractions. Therefore, we compared MU discharge characteristics and RFD during rapid contractions in chronic ST and UT individuals. The investigations were performed in two independent cohorts of chronically ST men, with trained elbow flexors (experiment 1, n ¼ 13, 6 ± 4 yr of training experience) or knee extensors (experiment 2, n ¼ 11, 9 ± 4 yr of experience), and compared with those of UT (n ¼ 12 and n ¼ 10, respectively). ST individuals had greater absolute elbow flexion and knee extension RFD throughout the first 150 ms of rapid contractions compared with UT, but this difference was absent for relative RFD. ST exhibited higher initial MU discharge rate in both biceps brachii (74 [68, 80] vs. 56 [50, 63] pulses per second (pps), P < 0.0001) and vastus lateralis (102 [90, 115] vs. 76 [63, 90] pps, P ¼ 0.0025) and a greater average number of MU discharges per second in both trained muscles in the early phase of rapid contractions. We provide novel evidence for a higher maximal MU discharge rate in strength-trained individuals. Interestingly, despite the augmented output of the spinal cord, no differences in relative RFD were observed, which suggests either greater maximal force enhancement of ST compared with UT and/or slowing of the intrinsic contractile properties by prolonged strength training.
Authors with CRIS profile
Involved external institutions
Loughborough University
United Kingdom (GB)
University of Maribor (UM) / Univerza v Mariboru
Slovenia (SI)
Imperial College London / The Imperial College of Science, Technology and Medicine
United Kingdom (GB)
University of Padua / Universita degli Studi di Padova
Italy (IT)
Ritsumeikan University / 立命館大学
Japan (JP)
University of Maryland School of Pharmacy
United States (USA) (US)
United Kingdom (GB)
University of Maribor (UM) / Univerza v Mariboru
Slovenia (SI)
Imperial College London / The Imperial College of Science, Technology and Medicine
United Kingdom (GB)
University of Padua / Universita degli Studi di Padova
Italy (IT)
Ritsumeikan University / 立命館大学
Japan (JP)
University of Maryland School of Pharmacy
United States (USA) (US)
How to cite
APA:
Škarabot, J., Casolo, A., Balshaw, T.G., Maeo, S., Lanza, M.B., Holobar, A.,... Del Vecchio, A. (2024). Greater motor unit discharge rate during rapid contractions in chronically strength-trained individuals. Journal of Neurophysiology, 132(6), 1896-1906. https://doi.org/10.1152/jn.00017.2024
MLA:
Škarabot, Jakob, et al. "Greater motor unit discharge rate during rapid contractions in chronically strength-trained individuals." Journal of Neurophysiology 132.6 (2024): 1896-1906.
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