engleski

Quadriceps muscle features assessment during fatigued cyclic dynamic contractions

Surface myoelectric signal analysis was carried out in order to determine particular quadriceps muscles features. Measurements are performed during fatigued exercise on leg-extension training device. Using spectrogram analysis, a time course of median frequency (MF) was computed. As a fatigue index, slope of regression line fitting maximum values of MF during each contraction in a least-square sense was used. MF at the beginning of exercise were calculated from regression line. Muscle with higher conduction velocity (rectus femoris) exhibited greater initial value as well as a greater reduction of MF over the course of the exercise. Higher differ-ences in initial values of MF between rectus femoris and both vasti muscles for males in comparison with females are shown.

muscle fatigue; dynamic contractions; surface EMG; time-frequency analysis

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