Resting potential and action potential of skeletal muscle Resting potential: normal skeletal muscle fibers in the resting state, normal skeletal muscle fibers inside and outside the muscle fiber membrane at rest state, there is a potential difference between the inside and outside of the muscle fiber membrane, and the membrane is positive outside the negative membrane. This potential difference is the potential difference. Resting potential The resting potential of the cat's skeletal muscle fiber is the resting potential of the cat's skeletal muscle fiber is -79..55 mV; The resting potential of the skeletal muscle fiber of the mouse is the resting potential of the skeletal muscle muscle fiber of the mouse is -99..88 mV; The skeletal muscle muscle fibers of guinea pigs are -85..55 mV for guinea pig skeletal muscle fibers; The skeletal muscle fiber of the mouse is skeletal muscle fiber of the mouse -61..00~~-88..99 mV; Human skeletal muscle fiber is -65 ~ ~ -87..44 mV for human skeletal muscle fibers; Action potential: When the muscle fiber is excited, the change of the conductive potential generated is called the action potential, and the action potential has an amplitude of 100 to 120 millivolts, and the duration is 2 to 4 milliseconds. The action potential recorded in the cell is single-phase negative wave, the amplitude is 100--120mv, and the duration is longer; the action potential recorded outside the cell is longer for the biphasic wave; the action potential recorded outside the cell is biphasic wave, amplitude It was 1.8 mv, which was significantly lower than intracellular recording. Normal myoelectric activity When there is no electrical activity when the normal skeletal muscle is completely relaxed, the electromyogram shown is a straight line called electric rest. Insert potential (inserted electrical activity) Insertion potential -- When inserting an electrode or moving an electrode that has been inserted into a muscle, there are some potential changes that have a short duration and a very low amplitude. This change in potential is called the insertion potential or the insertion of electrical activity. For insertion potential or insertion of electrical activity The insertion time is limited to the insertion potential of 1-3ms and the amplitude is 100μv. The duration of the inserted electrical activity is short, with an average duration of 300ms When the electrode stops moving, the insertion potential disappears. End plate potential Electromyography is performed in the endplate area, and self-generated activities can occur without muscle stimulation. These electrical activities occur in the form of endplate noise and endplate potential. End-plate noise is characterized by baseline instability. When end-plate noise occurs, a single endplate potential can often occur if the electrode is moved lightly. The endplate potential is single or dual phase. The endplate potential can be as large as 250μv with a time limit of 1-5ms. End-plate noise is derived from the end-plate potential at a long distance. Motor unit potential Waveform of motor unit potential According to the number of times the unit potential of the exercise unit leaves the baseline, it can be divided into single-phase, two-phase, three-phase and multi-phase waves. The normal electromyogram has 80% of the three-phase wave, 15% of the single-phase wave, and 5% of the multi-phase wave. 1 electrode and muscle fiber relative distance, direction and position The waveform of the potential of the motor unit is related to the relative distance, direction and position of the needle electrode and the moving muscle fiber. 2 The density of muscle fibers and the size of the motor unit in the exercise unit The density of muscle fibers in the motor unit and the magnitude of the magnitude of the motor unit are not only related to the distance of the active muscle fibers, but also depend on the number of muscle fibers involved in the activity. Therefore, the amplitude of the motor unit potential is a measure of the density of the muscle fibers. The magnitude of the motor unit potential is also related to the size of the unit of motion. 3 muscle contraction degree muscle contraction The degree of contraction of the muscle is different from the voltage of the motor unit potential. When the muscle contraction is mild, the myoelectric voltage is low, and when the degree of contraction is increased, the voltage is increased. This is due to the fact that when the muscles are slightly contracted, only a few exercise units with lower thresholds of excitement are generally involved in the work. These exercise units generally belong to the slow muscle motor unit, and their potential amplitude is low when excited. When the degree of contraction is increased, it is often possible to mobilize a sports unit with a higher threshold to participate in the work. These motor units are generally fast muscle motor units, and their potential amplitude is higher when excited. In addition, when the muscle undergoes a large-strength contraction, the muscle fibers tend to produce synchronous activity, and the amplitude of the myoelectric potential increases. 4 types of electrodes The action potential voltage guided by the double-pin electrode is higher than that of the concentric electrode. 5 electrode distance from the active muscle fibers The closer the electrode is to the moving muscle fiber, the higher the voltage, and vice versa. 6 hypoxia and low temperature When the temperature drops and oxygen is deficient, the myoelectric voltage drops. Increase the motor unit potential time limit. When the temperature changes by 1 degree Celsius, the motor unit potential time limit can be increased by 10-30%. 44 7 years As the age increases, the motor unit potential time increases. 8 muscle function status When muscle fatigue occurs, the amplitude of myoelectricity increases, and the unit time limit of exercise in the initial stage of fatigue is shortened. This is the result of synchronous discharge of the unit of motion during fatigue. When the muscles are excessively fatigued, the intramuscular environment is disordered and the function is lowered, which may hinder the generation and conduction of the action unit, resulting in an increase in the time limit of the exercise unit. Vegetable powder is a solid powder obtained by beating, filtering and spray drying bright vegetables. It has bright colors and delicious taste, and is a good helper for food additives and nutritional supplements. 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Electromyography test in sports - electric movement of skeletal muscle 
Factors affecting the potential of the motor unit: