Document Detail

Maximal motor unit firing rates during isometric resistance training in men.
MedLine Citation:
PMID:  16210447     Owner:  NLM     Status:  MEDLINE    
This study measured changes in maximal voluntary contraction (MVC) force, percentage maximal activation, maximal surface EMG, M-wave amplitude and average motor unit firing rates during the initial 3 weeks of isometric resistance training of the quadriceps muscle. Ten men participated in a resistance training programme three times a week for 3 weeks and 10 men participated as a control group. In the training group, MVC increased by 35% (from 761 +/- 77 to 1031 +/- 78 N) by the end of the 3 weeks. There were no changes in mean motor unit firing rates during submaximal or maximal voluntary contractions of 50 (15.51 +/- 1.48 Hz), 75 (20.23 +/- 1.85 Hz) or 100% MVC (42.25 +/- 2.72 Hz) with isometric resistance training. There was also no change in maximal surface EMG relative to the M-wave amplitude. However, there was a small increase in maximal activation (from 95.7 +/- 1.83 to 98.44 +/- 0.66%) as measured by the twitch interpolation technique. There were no changes in any of the parameters measured in the control group. It is suggested that mechanisms other than increases in average motor unit firing rates contributed to the increase in maximal force output with resistance training. Such mechanisms may include a combination of increased motor unit recruitment, enhanced protein synthesis, and changes in motor unit synchronization and muscle activation patterns across the quadriceps synergy.
A R Pucci; L Griffin; E Cafarelli
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2005-10-06
Journal Detail:
Title:  Experimental physiology     Volume:  91     ISSN:  0958-0670     ISO Abbreviation:  Exp. Physiol.     Publication Date:  2006 Jan 
Date Detail:
Created Date:  2005-12-23     Completed Date:  2006-06-08     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9002940     Medline TA:  Exp Physiol     Country:  England    
Other Details:
Languages:  eng     Pagination:  171-8     Citation Subset:  IM    
School of Kinesiology and Health Science, York University, Toronto, ON, Canada.
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MeSH Terms
Electric Stimulation
Exercise / physiology*
Femoral Nerve
Isometric Contraction / physiology*
Motor Neurons / physiology*
Quadriceps Muscle / innervation,  physiology*

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