Author Identifier
Cassio V. Ruas: https://orcid.org/0000-0002-6876-7190
Janet L. Taylor: https://orcid.org/0000-0001-8976-5162
Christopher Latella: https://orcid.org/0000-0002-5857-9671
G. Gregory Haff: https://orcid.org/0000-0002-0676-7750
Kazunori Nosaka: https://orcid.org/0000-0001-7373-4994
Document Type
Journal Article
Publication Title
European Journal of Applied Physiology
Publisher
Springer
School
School of Medical and Health Sciences / Centre for Human Performance
RAS ID
76026
Abstract
Purpose: We compared voluntary drive and corticospinal responses during eccentric (ECC), isometric (ISOM) and concentric (CON) muscle contractions to shed light on neurophysiological mechanisms underpinning the lower voluntary drive in a greater force production in ECC than other contractions. Methods: Sixteen participants (20–33 years) performed ISOM and isokinetic (30°/s) CON and ECC knee extensor contractions (110°–40° knee flexion) in which electromyographic activity (EMG) was recorded from vastus lateralis. Voluntary activation (VA) was measured during ISOM, CON and ECC maximal voluntary contractions (MVCs). Transcranial magnetic stimulation elicited motor-evoked potentials (MEPs) and corticospinal silent periods (CSP) during MVCs and submaximal (30%) contractions, and short-interval intracortical inhibition (SICI) in submaximal contractions. Results: MVC torque was greater (P < 0.01) during ECC (302.6 ± 90.0 Nm) than ISOM (269.8 ± 81.5 Nm) and CON (235.4 ± 78.6 Nm), but VA was lower (P < 0.01) for ECC (68.4 ± 14.9%) than ISOM (78.3 ± 13.1%) and CON (80.7 ± 15.4%). In addition, EMG/torque was lower (P < 0.02) for ECC (1.9 ± 1.1 μV.Nm−1) than ISOM (2.2 ± 1.2 μV.Nm−1) and CON (2.7 ± 1.6 μV.Nm−1), CSP was shorter (p < 0.04) for ECC (0.097 ± 0.03 s) than ISOM (0.109 ± 0.02 s) and CON (0.109 ± 0.03 s), and MEP amplitude was lower (P < 0.01) for ECC (3.46 ± 1.67 mV) than ISOM (4.21 ± 2.33 mV) and CON (4.01 ± 2.06 mV). Similar results were found for EMG/torque and CSP during 30% contractions, but MEP and SICI showed no differences among contractions (p > 0.05). Conclusions: The lower voluntary drive indicated by reduced VA during ECC may be partly explained by lower corticospinal excitability, while the shorter CSP may reflect extra muscle spindle excitation of the motoneurons from vastus lateralis muscle lengthening.
DOI
10.1007/s00421-024-05626-9
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Comments
Ruas, C. V., Taylor, J. L., Latella, C., Haff, G. G., & Nosaka, K. (2024). Neuromuscular characteristics of eccentric, concentric and isometric contractions of the knee extensors. European Journal of Applied Physiology. Advance online publication. https://doi.org/10.1007/s00421-024-05626-9