ORIGINAL ARTICLE

Effects of supramaximal exercise on the electromyographic signal

A M Hunter, A St Clair Gibson, M I Lambert, L Nobbs, T D Noakes

MRC/UCT Research Unit of Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape town, South Africa

Correspondence to:
Correspondence to:
Dr Hunter, Department of Sports Studies, University of Stirling, Stirling FK9 4LA, Scotland, UK;
a.m.hunter1{at}stir.ac.uk

Aim: To determine the neuromuscular recruitment characteristics during supramaximal exercise.

Methods: Ten healthy subjects completed the Wingate anaerobic test (WAT) cycling protocol. Electromyographic (EMG) data and rate of fatigue were recorded throughout the cycling.

Results: The mean (SD) rate of fatigue (decrease in power output) was 44.5 (8.6)%. No significant change was found in EMG amplitude. A significant decrease (p<0.01) in mean power frequency spectrum was found over the 30 second period.

Conclusions: During WAT, mean power frequency spectrum was attenuated with no decline in EMG amplitude, which may be caused by an accumulation of metabolites in the periphery. However, it is also possible that the feedback loop from intramuscular metabolism to the central nervous system is unable, within the 30 second period of the WAT, to affect neural recruitment strategy.

Keywords: fatigue; electromyographic amplitude; mean power frequency spectrum; Wingate anaerobic test

Abbreviations: WAT, Wingate anaerobic test; EMG, electromyographic; IEMG, integrated EMG; MPFS, mean power frequency spectrum; MVC, maximal isometric voluntary contraction

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