Electromyostimulation: mechanism of action, methodology, indications and contraindications

Electromyostimulation (syn.: myostimulation, neurostimulation, physiostimulation, myolifting) is the use of pulsed currents to affect the neuromuscular system.

Mechanism of action of electrical myostimulation

Usually, myostimulation is the variant using stationary electrodes (fixed) and currents with an intensity that allows obtaining visible muscle contractions, and myolifting is the work with moving electrodes, without visible muscle contractions, but with a pronounced sensation of current passage. When muscles or nerves are irritated by electric current, their biological activity changes and spike responses are formed. Electrical stimulation with a frequency exceeding 10 imp ^-1 causes a summation effect of depolarization and a strong prolonged contraction of muscles - serrated tetanus. With an increase in the frequency of electrical stimulation, the muscle does not relax due to the frequent succession of impulses and complete tetanus occurs, which with a further increase in the frequency of impulses is replaced by complete non-excitability (due to inactivation of chemosensitive valves of the subsynaptic membrane).

The most intense excitation occurs when the frequency ranges of electrical stimulation and impulses in nerve conductors coincide. Thus, under the influence of electrical stimulation of nerve endings with impulses over 50 imp ^-1, excitation of predominantly motor nerve conductors (A-o, and A-y fibers) and passive contraction of muscles by them occurs. One of the functions of nerve cells in the body is the regulation of the activity of other cells. Signals coming from nerves cause contractions of muscle cells. When these two types of cells (nerve and muscle) are "active", a rapid movement of ions through the cell membrane occurs. The electric current that arises in this case is called "action potential". Action potentials in nerve and muscle cells can be recorded using intracellular electrodes.

Pulses that are as close as possible in their form to the action potentials of nerve and muscle cells are called neuroimpulses (in cosmetology, neuroimpulse devices are popular, because the procedure is more comfortable, and the results are more noticeable than when using currents of a different form).

At the cellular level, the content of macroergic compounds (ATP, creatine phosphate) increases in the cytoplasm, their enzymatic activity increases, the rate of oxygen utilization increases, and energy costs for stimulated contraction decrease compared to voluntary contraction. Activation of blood supply and lymph flow leads to increased trophoenergetic processes. The expansion of peripheral vessels occurring simultaneously with passive muscle contraction leads to activation of blood flow in them. As a result, their weakened contractile function gradually increases. The effect of pulsed current is primarily aimed at muscle tone and response speed.

The contractions and relaxations of muscle fibers that occur during electrical stimulation prevent muscle atrophy, restore nervous regulation of muscle contractions, increase muscle strength and volume, and as a result, increase adaptation and the threshold of muscle fatigue.

Indications for electrical myostimulation:

1. Weakening of muscle tone.
2. Weakening of skin turgor.
3. Modeling the face oval.

Myostimulation is widely used to treat various types of facial and neck formations and restore muscle tone.

Myostimulation techniques

When changing the oval of the face, stimulation of the muscles located in the cheek area is performed. Self-adhesive skin electrodes are used for flabbiness of the neck. A course of procedures can significantly improve the tone of the subcutaneous muscle - platysma. With drooping of the upper eyelid, noticeable results can also be achieved without resorting to plastic surgery. Here, stimulation is often carried out with movable electrodes on a gel base (gel lifting). Pulsed current is also used to reduce the "double chin". Modern computerized devices allow you to set many parameters in the procedure, such as:

1. pulse shape;
2. pulse repetition frequency, most often a low pulse frequency is used - from tens to 1000 Hz.

The low frequency range used in physiotherapeutic cosmetology is determined by the electrophysiological lability of skeletal muscle fibers. They are capable of responding to electrical stimulation with a frequency of up to 1000 Hz by contraction. When using higher frequencies, current impulses are not perceived by nerves and muscles as separate irritants, which leads to a sharp decrease in the effectiveness of the effect.

Stimulation of skeletal, smooth muscles and nerve conductors requires different frequencies of pulse delivery. Therefore, the ability to change the frequency of pulses significantly expands the scope of application of the device. And the "frequency drift" function offers frequencies for all excitable cells in one "packet". Thus, more effective stimulation occurs and the muscles do not get used to the current so quickly. Different classes of devices can have different pulse delivery frequencies:

• VIP equipment - high-frequency pulse filling, recommended myostimulation frequency 400-600 Hz.
• Middle-class equipment - low-frequency pulse filling, recommended myostimulation frequency 10-230 Hz.

Pulse duration - from 0.1 to 1000 ms. Short pulses (0.1-0.5 ms) are very close to natural neuroimpulses and are the most convenient for myostimulation. Pulse increase and decrease rate: 3↔0.8. Waveform (pulse pack) - trapezoidal, rectangular, H-shaped, etc. Packet/pause ratio: contraction time/relaxation time: 5→3.9/2.5→1.9.

The current strength in the devices is provided for work on the face (max up to 10 mA) and for work on the body (50 mA). In procedures, the intensity of the current is set depending on the patient's sensations - contractions should be strong, but painless.

Pulses can be mono- and bipolar. Monopolar pulses cause dissociation of substances into ions and are also capable of moving electrically charged particles deep into tissues. Thus, monopolar pulse current can also be used for electrophoresis. The same substances are used as in electrophoresis with galvanic current. Bipolar pulses cause oscillatory movements of charged particles on biological membranes. Symmetrical bipolar pulses compensate for electrolysis, and there is no irritation of the skin under the electrodes. Bipolar pulses overcome skin resistance better and are felt as more comfortable.

The procedure is prescribed 2-3 times a week or every other day, duration is 20-40 minutes. The course is 15-20 procedures, the break between courses is 1 month.

Procedure diagram:

1. Place the electrodes, well moistened in water, on the active motor points of the muscles being worked on and secure with bandages (according to the diagrams).
2. Connect the wires, observing the polarity
3. Launch the program on the device.
4. Gradually increase the current until active muscle contractions occur. There should be no painful contraction. It is recommended to increase the intensity simultaneously in symmetrical areas.
5. After 3-4 minutes from the start of the program, increase the current strength (the adaptation process is complete, the muscles are prepared to work with a greater load).
6. After completing the procedure, remove the electrodes and turn off the device.
7. Treat the electrode locations with a toner or body lotion containing moisturizing and/or soothing components.

Recommendations for body procedures

Indications: muscle and skin laxity, cellulite, excess body weight, peripheral venous and arterial circulation disorders, venous-lymphatic insufficiency.

It is necessary to remember during the procedure about the individual sensitivity of each patient to electric current, to start the procedure with the selection of parameters at low values, gradually increasing them. With prolonged exposure to electric current, the effect of "addiction" may occur, which is partially leveled by well-designed programs, but does not exclude the alternation of myostimulating procedures with lymphatic drainage and electrolipolysis to obtain the maximum effect.

In trained people or athletes, the muscles are initially stronger and require significant load to maintain their shape and further training.

For patients of this category, special "sports" injuries have been created, but here too one should not forget about alternating the procedures of "training" and "relaxation" of muscles, since muscles can be overtrained. Lymphatic drainage and endermological programs for athletes are also included in the program.

Combination with other techniques:

• lymphatic drainage;
• electrophoresis;
• deep warmth;
• ultrasound therapy;
• endermologie;
• pressotherapy.

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