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Muscle Nerve. 2014 Jul;50(1):95-102. doi: 10.1002/mus.24098. Epub 2014 May 6.

Shifts in EMG spectral power during fatiguing dynamic contractions.

Author information

1
University of Oklahoma, Department of Health and Exercise Science, 110 Huston Huffman Center, Norman, OK, 73019-6081, USA.

Abstract

INTRODUCTION:

We examined the etiology of the electromyographic (EMG) spectral shift during dynamic fatigue.

METHODS:

Nineteen subjects (mean ± SD age = 22.4 ± 1.6 years) performed 50 consecutive maximal concentric isokinetic contractions of dominant leg extensors. Surface EMG signals were detected from the vastus lateralis, rectus femoris, and vastus medialis during each contraction, processed with a wavelet analysis, and the resulting spectra were decomposed with a nonparametric spectral decomposition procedure.

RESULTS:

The results indicated that the decreases in EMG frequency during the 50 contractions were generally due to reductions in high-frequency power and increases in low-frequency power. In addition, the spectral shifts were most pronounced for the rectus femoris, followed by the vastus lateralis, and then the vastus medialis.

CONCLUSIONS:

The spectral decomposition procedure is much more sensitive for tracking dynamic fatigue than is EMG mean frequency or median frequency.

KEYWORDS:

dynamic; electromyography; fatigue; spectra; wavelet

PMID:
24122808
DOI:
10.1002/mus.24098
[Indexed for MEDLINE]

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