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Wide pulse-high frequency neuromuscular stimulation of triceps surae induces greater muscle fatigue as compared to conventional stimulation.
MedLine Citation:
PMID:  24674861     Owner:  NLM     Status:  Publisher    
We compared the extent and origin of muscle fatigue induced by short pulse-low frequency (CONV) and wide pulse-high frequency (WPHF) neuromuscular electrical stimulation. We expected CONV contractions to mainly originate from depolarization of axonal terminal branches (spatially determined muscle fiber recruitment) and WPHF contractions to be partly produced via a central pathway (motor unit recruitment according to size principle). Greater neuromuscular fatigue was therefore expected following CONV in comparison to WPHF. Fourteen healthy subjects underwent 20 WPHF (1 ms-100 Hz) and CONV (50 µs-25 Hz) evoked isometric triceps surae contractions (work:rest periods 20:40 s) at an initial target of 10% of maximal voluntary contraction (MVC) force. Force-time integral of the 20 evoked contractions (FTI) used as main index of muscle fatigue; MVC force loss was also quantified. Central and peripheral fatigue were assessed by voluntary activation level (VAL) and paired stimulation amplitudes, respectively. FTI in WPHF was significantly lower than in CONV (median values: 806 vs. 1794 N.s). The reductions in MVC force (WPHF: -7.0 ± 2.7%; CONV: -6.2 ± 2.5%; p<0.01) and paired stimulation amplitude (WPHF: -8.0 ± 4.0%; CONV: -7.4 ± 6.1%; p<0.001) were similar between conditions, whereas no change was observed for VAL (p>0.05). Overall, our results showed a different motor unit recruitment pattern between the two NMES modalities with a lower FTI indicating greater muscle fatigue for WPHF, possibly limiting the presumed benefits for rehabilitation programs.
Daria Neyroud; David Dodd; Julien Gondin; Nicola A Maffiuletti; Bengt Kayser; Nicolas Place
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2014-3-27
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  -     ISSN:  1522-1601     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2014 Mar 
Date Detail:
Created Date:  2014-3-28     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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