Document Detail


Time course of postactivation potentiation during intermittent submaximal fatiguing contractions in endurance- and power-trained athletes.
MedLine Citation:
PMID:  19620919     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
This study aimed to measure time course of postactivation potentiation during intermittent submaximal fatiguing isometric contractions in 2 groups of subjects with different physical training history. Fifteen men subjects (8 endurance-trained athletes [END] and 7 power-trained athletes [POW]) performed a 10-minute intermittent (5-second contraction, 5-second rest) knee extension exercise at 50% of their maximal voluntary isometric contraction. Mechanical (peak twitch torque, Pt) and electrophysiological (M-wave) responses following electrical stimulation of the femoral nerve were measured at rest and every 10 s throughout exercise. Vastus lateralis (VL) muscle activity (root mean square, RMS) was recorded during each contraction, and the RMS/M ratio was calculated. A significant increase in Pt (+52%, p < 0.01) was observed in both groups during the first minute of the exercise. Thereafter Pt decreased dramatically (p < 0.05) in POW whereas it remained above baseline values in END until the end of exercise. The VL RMS/M ratio increased from 7 minutes of exercise for the entire population of subjects, but showed a tendency toward greater and earlier increase in POW. Our study showed the effectiveness of an intermittent submaximal preconditioning protocol to induce similar potentiation (5-10 repetitions of 5-second submaximal contraction at 50% MVC of knee-extensors) for 2 groups of trained-individuals with different muscular profiles (END vs. POW). The enhanced fatigue resistance of endurance athletes allows the potentiating effect to prevail longer over the fatigue effect during all the 10-minute exercise. The proposed conditioning protocol (moderate-intensity, short-duration intermittent exercise) as an interesting alternative compared to MVC is adequate to warm all athletes and increase sports performance.
Authors:
Claire Morana; Stéphane Perrey
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of strength and conditioning research / National Strength & Conditioning Association     Volume:  23     ISSN:  1533-4287     ISO Abbreviation:  J Strength Cond Res     Publication Date:  2009 Aug 
Date Detail:
Created Date:  2009-08-05     Completed Date:  2009-11-02     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9415084     Medline TA:  J Strength Cond Res     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1456-64     Citation Subset:  IM    
Affiliation:
Faculty of Sport Sciences, EA 2991 Motor Efficiency and Deficiency Laboratory, Montpellier, France.
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MeSH Terms
Descriptor/Qualifier:
Adult
Electric Stimulation
Electromyography
Femoral Nerve / physiology
Humans
Isometric Contraction / physiology*
Knee Joint / physiology
Male
Muscle Fatigue / physiology*
Muscle, Skeletal / innervation*,  physiology*
Physical Education and Training / methods*
Physical Endurance / physiology

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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