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Corticospinal excitability and motor representation after long-term resistance training

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journal contribution
posted on 05.08.2021, 13:36 by Sumiaki Maeo, Tom BalshawTom Balshaw, Marcel B. Lanza, Ricci Hannah, Jonathan FollandJonathan Folland
It is poorly understood how the central nervous system adapts to resistance training, especially after years of exposure. We compared corticospinal excitability and motor representation assessed with transcranial magnetic stimulation (TMS) between long-term resistance trained (LRT, ≥3 years) versus untrained (UNT) males (n = 15/group). Motor-evoked potentials (MEPs) were obtained from the biceps brachii during isometric elbow flexion. Stimulus-response curves were created at the hotspot during 10% maximum voluntary torque (MVT) contractions. Maximum peak-to-peak MEP amplitude (MEPmax) was acquired with 100% stimulator output intensity, whilst 25%−100% MVT was produced. Maps were created during 10% MVT contractions, with an individualised TMS intensity eliciting 20% MEPmax at the hotspot. LRT had a 48% lower stimulus-response curve slope than UNT (p <.05). LRT also had a 66% larger absolute map size, although TMS intensity used for mapping was greater in LRT versus UNT (48% vs. 26% above active motor threshold) to achieve a target 20% MEPmax at the hotspot, due to the lower slope of LRT. Map size was strongly correlated with the TMS intensity used for mapping (r = 0.776, p <.001). Once map size was normalised to TMS intensity, there was no difference between the groups (p =.683). We conclude that LRT had a lower stimulus-response curve slope/excitability, suggesting higher neural efficiency. TMS map size was overwhelmingly determined by TMS intensity, even when the MEP response at the hotspot was matched among individuals, likely due to larger current spread with higher intensities. Motor representation appears similar between LRT and UNT given no difference in the normalised map size.

Funding

Japan Society for the Promotion of Science, Grant/Award Number: 18K17837

History

School

  • Sport, Exercise and Health Sciences

Published in

European Journal of Neuroscience

Volume

53

Issue

10

Pages

3416 - 3432

Publisher

Wiley

Version

VoR (Version of Record)

Rights holder

© The Authors

Publisher statement

This is an Open Access Article. It is published by Wiley under the Creative Commons Attribution 4.0 International Licence (CC BY 4.0). Full details of this licence are available at: https://creativecommons.org/licenses/by/4.0/

Acceptance date

16/03/2021

Publication date

2021-04-07

Copyright date

2021

ISSN

0953-816X

eISSN

1460-9568

Language

en

Depositor

Prof Jonathan Folland. Deposit date: 30 July 2021