Document Detail

Neuromuscular fatigue and potentiation following two successive high intensity resistance exercise sessions.
MedLine Citation:
PMID:  15185085     Owner:  NLM     Status:  MEDLINE    
Resistance exercise can result in both potentiating and fatiguing responses. These responses can acutely affect performance, which may affect subsequent exercise sessions in the same day. The purpose of this investigation was to study the acute neuromuscular responses to two high intensity training sessions in the same day. Twelve recreationally trained males performed two training sessions, each involving ten sets of five repetitions in the speed squat exercise. For the initial session (HIT-1), the barbell load was constant at 70% one repetition maximum, whereas during the second session (HIT-2), barbell load decreased if movement velocity decreased. Neuromuscular performance testing consisted of unilateral isometric knee extensor actions performed prior to the training day (PRE) and following each testing session. Prior to the sessions, subjects provided a muscle biopsy for myosin heavy chain analysis. Peak force was impaired 16.9 (9.5)% (P approximately 0.00; d=1.62) following HIT-1 and 19.9 (18.4)% (P approximately 0.00; d=1.94) following HIT-2. Initial rate of force development was depressed from PRE following HIT-1 (P approximately 0.00; d=1.74) and HIT-2 (P approximately 0.00; d=2.18); however, this was dependent on muscle fiber composition. Significant correlations existed between the change score for initial rate of force development from HIT-1 to HIT-2 and myosin heavy chain I (r= -0.60; P=0.04) and IIa (r=0.69; P=0.01) expression. Impaired neuromuscular performance following HIT-1 may occur due to low frequency fatigue. For individuals with predominantly myosin heavy chain IIa, HIT-2 appeared to induce post-activation potentiation, resulting in restoration of the initial rate of force development.
L Z F Chiu; A C Fry; B K Schilling; E J Johnson; L W Weiss
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Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  European journal of applied physiology     Volume:  92     ISSN:  1439-6319     ISO Abbreviation:  Eur. J. Appl. Physiol.     Publication Date:  2004 Aug 
Date Detail:
Created Date:  2004-10-04     Completed Date:  2004-12-07     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  100954790     Medline TA:  Eur J Appl Physiol     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  385-92     Citation Subset:  IM    
Musculoskeletal Biomechanics Research Laboratory, University of Southern California, 1540 East Alcazar Street, CHP-155, Los Angeles, CA 90089, USA.
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MeSH Terms
Contractile Proteins / physiology
Electrophoresis, Polyacrylamide Gel
Exercise / physiology*
Isometric Contraction / physiology
Muscle Contraction / physiology
Muscle Fatigue / physiology*
Muscle, Skeletal / innervation*,  metabolism,  physiology*
Myosin Heavy Chains / metabolism
Neurons / physiology*
Reg. No./Substance:
0/Contractile Proteins; 0/Myosin Heavy Chains

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