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Changes in surface EMG assessed by discrete wavelet transform during maximal isometric voluntary contractions following supramaximal cycling.
MedLine Citation:
PMID:  23001683     Owner:  NLM     Status:  Publisher    
To better understand characteristics of neuromuscular fatigue in supramaximal cycling exercise, this study examined changes in surface electromyography (sEMG) frequency during maximal voluntary isometric contractions (MVC) following a 30-s Wingate anaerobic test (WAnT) using discrete wavelet transform (DWT). The changes in sEMG were also compared between DWT and mean frequency (MNF) obtained by fast Fourier transform (FFT). 17 healthy men performed a WAnT with a 7.5 % of body mass load. Knee extensor MVC torque was measured before and 1, 3, 6, 9, 12 and 15 min following WAnT, and sEMG was recorded from vastus lateralis muscle during the torque measures. sEMG was analysed for (RMS), MNF by FFT and frequency domains of DWT (divided into six domains). MVC torque decreased 21-23 % at 3-15 min, RMS increased 26-34 % at 1-15 min, and MNF decreased 8-10 % from baseline (76.3 ± 3.2 Hz) at 1-3 min post-cycling (P < 0.05). The DWT frequency domains showed that the changes lasted longer than MNF such that the intensity increased at 12 and 15 min for domain 2 (125-250 Hz), all time points for domain 3 (62.5-125 Hz), and 1-6 min for domains 4 (31.2-62.5 Hz) and 5 (15.6-31.2 Hz). The magnitude of increase in the intensity at 1 min post-exercise (45-60 %) was largest for domains 3 and 5 (P < 0.05). A significant correlation was evident only between the magnitude of changes in the domain 5 and MNF (r = -0.56). It is concluded that DWT provides information on neuromuscular fatigue that is not detected by MNF derived from FFT.
Luis Peñailillo; Rony Silvestre; Kazunori Nosaka
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-9-23
Journal Detail:
Title:  European journal of applied physiology     Volume:  -     ISSN:  1439-6327     ISO Abbreviation:  Eur. J. Appl. Physiol.     Publication Date:  2012 Sep 
Date Detail:
Created Date:  2012-9-24     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  100954790     Medline TA:  Eur J Appl Physiol     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
School of Kinesiology, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile,
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