[Studies on the non-fatigue specificity of the fatigue-related sEMG signal parameters]

Abstract

Objective: To investigate the non-fatigue specificity of the changes of the fatigue-related parameters of sEMG signal during muscle static contractions.

Method: The sEMG signals of biceps brachii (BB) and triceps brachii (TB) were recorded in 10 subjects during 1 min sustained right elbow isometric flexion. Changes of a series of fatigue-related indices such as MPF, MF, ZCR, AEMG and Lempel-ziv complexity were then analyzed. MVCs of the extensor (TB) were measured before and immediately after fatiguing flexion.

Result: MPF, MF, ZCR and Lempel-ziv complexity of BB all decreased regularly and linearly with continuation of contraction. Whereas AEMG of BB increased linearly. The MVCs of TB were (14.0 +/- 3.2)kg and (14.6 +/- 2.6)kg respectively before and after BB fatiguing contraction. But the slopes of decrease of MPF, MF, ZCR and Lempel-ziv complexity of TB were significantly steeper than those of BB. The AEMG of TB was almost unchanged.

Conclusion: The changes of time- and frequency-domain indices and Lempel-ziv complexity of sEMG signal were not as a result of muscle fatigue specifically. Fatigue might not be the only factor that caused the changes of the indices mentioned above.