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JEET, Vol. 12, No. 4, July 2017
Endurance Capacity of the Biceps Brachii Muscle Using the High-to-Low Ratio between Two Signal Spectral Moments of Surface EMG Signals during Isotonic Contractions
Ki-Young Lee
Area D - Information and Control
Abstract ? Many researchers had examined the validity of using the high-to-low ratio between two fixed frequency band amplitudes (H/L-FFB) from the surface electromyography of a face and body as the first spectral index to assess muscle fatigue. Despite these studies, the disadvantage of this index is the lack of a criterion for choosing the optimal border frequency. We tested the potential of using the high-to-low ratio between two signal spectral moments (H/L-SSM), without fixed border frequencies, to evaluate muscle fatigue and predict endurance time (Tend), which was determined when the subject was exhausted and could no longer follow the fixed contraction cycle. Ten healthy participants performed five sets of voluntary isotonic contractions until they could only produce 10% and 20% of their maximum voluntary contraction (MVC). The Tend values for all participants were 138 35 s at 10% MVC and 69 20 s at 20% MVC. Changes in conventional spectral indices, such as the mean power frequency (MPF), Dimitrov spectral index (DSI), H/L-FFB, and H/L-SSM, were extracted from surface EMG signals and were monitored using the initial slope computed every 10% of Tend as a statistical indicator and compared as a predictor of Tend. Significant correlations were found between Tend and the initial H/L-SSM slope as computed over 30% of Tend. In conclusion, initial H/L-SSM slope can be used to describe changes in the spectral content of surface EMG signals and can be employed as a good predictor of Tend compared to that of conventional spectral indices.
Keyword Electromyography,Signal spectral moment,High-to-low ratio,Isotonic contractions,Endurance time (Tend)
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