European Journal of Applied Physiology

, Volume 117, Issue 7, pp 1359–1371 | Cite as

Adaptations in corticospinal excitability and inhibition are not spatially confined to the agonist muscle following strength training

  • Joel Mason
  • Ashlyn Frazer
  • Deanna M. Horvath
  • Alan J. Pearce
  • Janne Avela
  • Glyn Howatson
  • Dawson Kidgell
Original Article



We used transcranial magnetic stimulation (TMS) to determine the corticospinal responses from an agonist and synergist muscle following strength training of the right elbow flexors.


Motor-evoked potentials were recorded from the biceps brachii and flexor carpi radialis during a submaximal contraction from 20 individuals (10 women, 10 men, aged 18–35 years; training group; n = 10 and control group; n = 10) before and after 3 weeks of strength training at 80% of 1-repetition maximum (1-RM). To characterise the input–output properties of the corticospinal tract, stimulus–response curves for corticospinal excitability and inhibition of the right biceps brachii and flexor carpi radialis were constructed and assessed by examining the area under the recruitment curve (AURC).


Strength training resulted in a 29% (P < 0.001) increase in 1-RM biceps brachii strength and this was accompanied by a 19% increase in isometric strength of the wrist flexors (P = 0.001). TMS revealed an increase in corticospinal excitability AURC and a decrease in silent period duration AURC for the biceps brachii and flexor carpi radialis following strength training (all P < 0.05). However, the changes in corticospinal function were not associated with increased muscle strength.


These findings show that the corticospinal responses to strength training of a proximal upper limb muscle are not spatially restricted, but rather, results in a change in connectivity, among an agonist and a synergistic muscle relevant to force production.


Agonist Corticospinal excitability Corticospinal inhibition Voluntary strength Strength training Synergist 



One-repetition maximum


Area under the recruitment curve


Active motor threshold


Cervicomedullary motor–evoked potentials


γ-Aminobutyric acid


Long-term potentiation


Motor-evoked potentials


Maximal voluntary isometric contraction


Primary motor cortex


Root-mean square electromyography


Surface electromyography


Short-interval cortical inhibition


Transcranial magnetic stimulation



This research did not receive any specific Grant from funding agencies in the public, commercial, or not-for-profit sectors.

Compliance with ethical standards

Conflict of interest

None of the authors have potential conflicts of interest to be disclosed.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2017

Authors and Affiliations

  • Joel Mason
    • 1
  • Ashlyn Frazer
    • 1
  • Deanna M. Horvath
    • 2
  • Alan J. Pearce
    • 1
  • Janne Avela
    • 3
  • Glyn Howatson
    • 4
    • 5
  • Dawson Kidgell
    • 1
  1. 1.Discipline of Exercise Science, School of Allied HealthLa Trobe UniversityMelbourneAustralia
  2. 2.Department of Physiology, Anatomy and Microbiology, School of Life SciencesLa Trobe UniversityMelbourneAustralia
  3. 3.Department of Biology and Physical ActivityUniversity of JyväskyläJyväskyläFinland
  4. 4.Department of Sport, Exercise and RehabilitationNorthumbria UniversityNewcastleUK
  5. 5.Water Research Group, School of Environmental Sciences and DevelopmentNorthwest UniversityPotchefstroomSouth Africa

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