Short-term strength training does not change cortical voluntary activation

Lee, Michael, Gandevia, Simon C. and Carroll, Timothy J. (2009) Short-term strength training does not change cortical voluntary activation. Medicine and Science in Sports and Excercise, 41 7: 1452-1460. doi:10.1249/MSS.0b013e3181998837

Author Lee, Michael
Gandevia, Simon C.
Carroll, Timothy J.
Title Short-term strength training does not change cortical voluntary activation
Journal name Medicine and Science in Sports and Excercise   Check publisher's open access policy
ISSN 0195-9131
Publication date 2009
Sub-type Article (original research)
DOI 10.1249/MSS.0b013e3181998837
Volume 41
Issue 7
Start page 1452
End page 1460
Total pages 9
Editor K. Pandolf
K.O. Wilson
Place of publication Baltimore, MD
Publisher Lippincott Williams & Wilkins
Collection year 2010
Language eng
Subject C1
920111 Nervous System and Disorders
110603 Motor Control
1109 Neurosciences
Abstract Purpose: The neural mechanisms responsible for strength improvement in the early phase of strength training are unknown. One hypothesis is that strength increases because of increased neural drive to the trained muscles. Here, we used twitch interpolation to assess voluntary activation before and after a 4-wk strength training program. Methods: Twelve volunteers performed unilateral strength training for the right wrist abductors (three times per week). Control subjects (n = 11) practiced the same movement without resistance. We assessed voluntary activation of the trained muscles during wrist abduction and extension contractions using twitch interpolation with motor nerve and motor cortical stimulation. Results: Strength training increased wrist abduction maximal voluntary contraction (MVC) force for the trained hand by 11.0% (±8.7, P < 0.01). MVC of the untrained wrist was unchanged. There were no significant changes in wrist extension MVC force in either group. During submaximal wrist abduction, but not extension contractions, the average size of the superimposed twitches produced by cortical stimulation was significantly larger after strength training (P < 0.01). Furthermore, the direction of the twitches produced by cortical stimulation during wrist abductions and maximal wrist extension shifted toward abduction (P = 0.04). There were neither significant changes in voluntary activation measured during MVC with motor nerve or motor cortical stimulation nor changes in the amplitude of evoked EMG responses to motor cortical or motor nerve stimulation. Conclusions: Four weeks of strength training produced a small increase in MVC that was specific to the training direction. Although maximal voluntary activation did not change with short-term strength training, the changes in direction and amplitude of cortically evoked twitches suggest that motor cortical stimulation (and presumably volition) can generate motor output more effectively to the trained muscles.
Keyword twitch interpolation
resistance training
neural drive
Q-Index Code C1
Q-Index Status Confirmed Code

Document type: Journal Article
Sub-type: Article (original research)
Collections: 2010 Higher Education Research Data Collection
School of Human Movement and Nutrition Sciences Publications
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Created: Wed, 25 Nov 2009, 13:16:37 EST by Deborah Noon on behalf of School of Human Movement and Nutrition Sciences