Short-interval intracortical inhibition of the biceps brachii in chronic-resistance versus non-resistance-trained individuals
- 106 Downloads
The purpose of this study was to investigate the effects of chronic resistance training on corticospinal excitability and short intracortical inhibition of the biceps brachii. Eight chronic resistance-trained (RT) and eight non-RT participants completed one experimental session including a total of 30 brief (7 s) elbow flexors isometric contractions at various force outputs [15, 25 and 40% of maximum voluntary contraction (MVC)]. Before the contractions, MVC, maximal compound muscle action potential (Mmax) during 5% MVC and active motor threshold (AMT) at the three various force outputs were recorded. MVC force of the chronic-RT group was 24% higher than the non-RT group (p ≤ 0.001; ω2 = 0.72). The chronic-RT group had lower AMTs at targeted forces of 15 and 25% MVC (p = 0.022 and p = 0.012, respectively) compared to the non-RT group. During 25 and 40% of MVC, the non-RT group exhibited decreased SICI in comparison to the chronic-RT group (p = 0.008; ω2 = 0.35 and p = 0.03; ω2 = 0.21, respectively). However, SICI did not differ between groups at 15% MVC (p = 0.62). In conclusion, chronic resistance training significantly reduces SICI. This suggests the presence of an adaptive process of inhibitory and facilitatory network activation, which may cancel out the SICI, allowing for increased corticomotor drive to the exercised muscle following a long period of resistance training.
KeywordsFacilitation Inhibition Resistance training Transcranial magnetic stimulation Voluntary contraction
This study was supported by the Natural Sciences and Engineering Research Council of Canada (2018-03876).
Compliance with ethical standards
Conflict of interest
The authors declare they have no conflict of interest.
- Hunter SK, McNeil CJ, Butler JE, Gandevia SC, Taylor JL (2016) Short-interval cortical inhibition and intracortical facilitation during submaximal voluntary contractions changes with fatigue. Exp Brain Res 234:2541–2551. https://doi.org/10.1007/s00221-016-4658-9 CrossRefPubMedPubMedCentralGoogle Scholar
- Philpott DT, Pearcey GE, Forman D, Power KE, Button DC (2015) Chronic resistance training enhances the spinal excitability of the biceps brachii in the non-dominant arm at moderate contraction intensities. Neurosci Lett 585:12–16. https://doi.org/10.1016/j.neulet.2014.11.009 CrossRefPubMedGoogle Scholar
- Rossini PM, Burke D, Chen R et al (2015) Non-invasive electrical and magnetic stimulation of the brain, spinal cord, roots and peripheral nerves: basic principles and procedures for routine clinical and research application. An updated report from an I.F.C.N. Committee. Clin Neurophysiol 126:1071–1107. https://doi.org/10.1016/j.clinph.2015.02.001 CrossRefPubMedPubMedCentralGoogle Scholar