Fatigue and Abnormal State Detection by Using EMG Signal During Football Training

2. Emg Signal And Feature Extraction

According to the theory of ion current, the repolarization and depolarization of muscle cell membranes are the fundamental reason for the formation of electromyography. The cell membrane is a semi-permeable membrane. In the state of muscle relaxation, due to the effect of the ion pump, the cations outside the cell membrane are higher than that inside the membrane to form polarization state in which the potential of the muscle cell membrane is higher than the potential inside the cell membrane. The difference between the internal potential and external potential is about In the state of muscle contraction, the cell membrane is stimulated and its permeability also changes. More sodium ion channels are opened and a large amount of sodium ions flow into the cell membrane. The potential difference between the inside and outside of the membrane reaches up to . When the muscle relaxes, sodium ions quickly outflow and the channels are closed until the potential difference is restored when resting, that is repolarization. The potential difference changes produced by the above process are the source of muscle electricity.