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Neurophysiological Responses After Short-Term Strength Training of the Biceps Brachii Muscle

Kidgell, Dawson J and Stokes, Mark A and Castricum, Troy J and Pearce, Alan J (2010) Neurophysiological Responses After Short-Term Strength Training of the Biceps Brachii Muscle. Journal of Strength and Conditioning Research, 24 (11). pp. 3123-3132. ISSN 1064-8011 (print) 1533-4287 (online)

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Abstract

Kidgell, DJ, Stokes, MA, Castricum, TJ, and Pearce, AJ. Neurophysiological responses after short-term strength training of the biceps brachii muscle. J Strength Cond Res 24(11): 3123-3132, 2010. The neural adaptations that mediate the increase in strength in the early phase of a strength training program are not well understood; however, changes in neural drive and corticospinal excitability have been hypothesized. To determine the neural adaptations to strength training, we used transcranial magnetic stimulation (TMS) to compare the effect of strength training of the right elbow flexor muscles on the functional properties of the corticospinal pathway. Motor-evoked potentials (MEPs) were recorded from the right biceps brachii (BB) muscle from 23 individuals (training group; n = 13 and control group; n = 10) before and after 4 weeks of progressive overload strength training at 80% of 1-repetition maximum (1RM). The TMS was delivered at 10% of the root mean square electromyographic signal (rmsEMG) obtained from a maximal voluntary contraction (MVC) at intensities of 5% of stimulator output below active motor threshold (AMT) until saturation of the MEP (MEPmax). Strength training resulted in a 28% (p = 0.0001) increase in 1RM strength, and this was accompanied by a 53% increase (p = 0.05) in the amplitude of the MEP at AMT, 33% (p = 0.05) increase in MEP at 20% above AMT, and a 38% increase at MEPmax (p = 0.04). There were no significant differences in the estimated slope (p = 0.47) or peak slope of the stimulus-response curve for the left primary motor cortex (M1) after strength training (p = 0.61). These results demonstrate that heavy-load isotonic strength training alters neural transmission via the corticospinal pathway projecting to the motoneurons controlling BB and in part underpin the strength changes observed in this study.

Item Type: Article
Uncontrolled Keywords: ResPubID21648, transcranial magnetic stimulation, controlled strength training, biceps brachii, electromyography, corticospinal
Subjects: Faculty/School/Research Centre/Department > School of Sport and Exercise Science
FOR Classification > 1106 Human Movement and Sports Science
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Depositing User: VUIR
Date Deposited: 21 May 2012 04:27
Last Modified: 13 Jan 2015 04:23
URI: http://vuir.vu.edu.au/id/eprint/7165
DOI: 10.1519/JSC.0b013e3181f56794
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Citations in Scopus: 15 - View on Scopus

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