Muscle Stimulation – Russian Current
Currently, there is an agreement among researchers that the Russian current is an alternating current of medium frequency that can be modulated by “stripes and used for excitomotor purposes. According to Adel and Luykx (1990), the Soviet researcher who developed this type of current used 50Hz bursts because it is located approximately in the center of the frequency spectrum used for tetanic contractions of musculature (40 to (Borges, EVANGELISTA AND MARCHI 2006).
The choice of frequency (2000 to 4000Hz) was due to the duration of the absolute refractory period of the motor nerve which is in the band of 0.2 to 0.5ms (FURINI and LARGO apud COHEN AND ABDALLA, 2003).
The stimulation frequencies necessary for the uniform somatic tetanus result are different: for slow muscle filaments (tonic, type I, red and strong to fatigue), lower frequencies must be used; higher frequencies are used for fast muscle filaments (aphonic, type II, white and less strong to fatigue) (SCOTT, 1998).
According to some authors, to work the tonic filaments of a muscle with postural function, a frequency of 20 to 30Hz is necessary. If the option is to work aphonic filaments (more dynamic function), a modulated frequency of 50 to 150 is necessary (Borges, EVANGELISTA AND MARCHI 2006).
According to some authors, muscle electrostimulation with frequencies greater than its maximum repolarization / depolarization speed causes those filaments to depolarize at their own frequency, causing depolarization to be asynchronous.
This basically occurs for two reasons:
1. The possibility of the medium frequency having a value above the depolarization frequency, being able to coincide stimulation with the absolute refractory period, causing greater difficulty in repolarization.
2. High frequency can cause intense fatigue of the motor end plate. The nerve then demonstrates the phenomenon of accommodation, causing the refractory period to become longer over time.
To avoid what was mentioned above, we find in the Russian current the features of interruption. By virtue of the bursts, there is an interruption where the current is zero, favoring the prevention of motor end plate fatigue.
Modulation is the interruption of the medium frequency at low frequencies, allowing the work of different types of muscle filaments according to the appropriate speeds to depolarize each type of motor neuron (aphonic or tonic filament).
Alternating medium-frequency currents between 2000 and 4000Hz are used because they are relatively pleasant, rarely injure the skin and provide maximum tightness in the muscle when used with sufficient intensity.
One reason why electrostimulation is more effective is that voluntary exercise lies in the difference in recruitment of muscle filaments. At the beginning of the rehabilitation process, fast contraction filaments are generally not activated in order to avoid stress on the joint. Electrostimulation can work this type of filaments by choosing the most appropriate frequency (80Hz).
Muscle electrostimulation has gained ground in aesthetic treatments with the aim of minimizing flaccidity. It should be observed whether the site has a pile of fat in the region, as this makes current passage difficult, with the possibility of uselessness.
Voluntary muscle contraction can be incentivized, as it seeks to boost results. If performed, the ON time should be reduced (1 to 2 seconds) and the OFF time adjusted to 3 to 4 seconds.
The total session time for beginners should be 10 to 20 minutes per muscle group and 30 to 40 minutes for treatments requiring greater conditioning (athletes, physical activity practitioners) (Borges, EVANGELISTA AND MARCHI 2006).
Muscle contraction process
Neural action potential: Nerve signals are transmitted through action potentials. This part of the normal negative resting potential moves to a positive potential and ends with a rapid variation returning to the negative potential. In the resting stage, the membrane is “polarized” due to the membrane potential being negative between -70mV and -90mV (depending on the diameter of the nerve and muscle filament). Membrane depolarization occurs when influenced by sodium influx, leaving it positive, and repolarization occurs when potassium diffuses out of the cell leaving the membrane negative again.
Myelinated filaments have an envelope called the myelin sheath. It consists of Schwann cells and reduces ion flow through the membrane by up to 5000 times, having an insulating function. At the junction between two Schwann cells remains a small uninsulated region called the node of Ranvier. The action potential in myelinated strands occurs only in these regions, carrying out saltatory conduction, increasing nerve transmission speed and conserving energy for the filament.
The neuromuscular junction: The nerve filaments, after penetrating the muscle belly, branch out and stimulate the muscle filaments. Each of the nerve endings form a neuromuscular junction. The motor end plates are constituted of these branching terminations that invaginate in the plasmatic membrane, where there is a high concentration of the neurotransmitter acetylcholine (GUYTON AND HALL, 2002).
Muscle contraction mechanism:
– The action potential occurs along the motor nerve to its terminations in the muscle filaments;
– The nerve secretes acetylcholine.
– Acetylcholine opens channels through protein molecules in the muscle filament membrane.
– Sodium ions flow into the membrane of the muscle filament triggering the action potential.
– The action potential propagates.
– Depolarization occurs with the release of calcium ions from the sarcoplasmic reticulum to the myofibrils.
– The actin and myosin filaments slide past each other, causing muscle contraction.
– Removal of the calcium ions, ending contraction.
According to research carried out by Pires (2004), the electrical activity was analyzed before, during and after neuromuscular electrostimulation with low and medium frequency. The results indicated a statistically significant difference (p <0.05) between groups and at all times studied, revealing greater fatigue presence in the group stimulated with low frequency (GUYTON AND HALL, 2002).
The case study described by Borges and Valentin (2002) on flaccidity and rectoabdominal distention in the postpartum period of a normal delivery achieved as a result the reduction of the abdominal perimeter by shortening of this musculature in its longitudinal dimension.
On the other hand, following up on the results achieved through the use of the tape measure led to the conclusion that there was also a transverse reduction in the distance between the two muscle segments tested. In addition to this, subjective evaluation and regular follow-up of patients showed improvement in tone and muscle trophism.
The study cited above showed favorable results that justify its use in puerperal therapy. Satisfactory improvement could be observed in the flaccidity picture that patients presented and treatment was able to reduce measurements by shortening the rectoabdominal in its longitudinal dimension. With the use of the tape measure, the reduction of the dietase was evident in a shorter period than the physiological one. This fact is very important, as it was able to demonstrate a rapid improvement in abdominal muscle function.
Analgesia can also be verified when used at a frequency of 4000Hz with modulation of 4 to 6Hz (similar to acupuncture TENS) for chronic pain and 100Hz for acute pains (similar to conventional TENS) (Borges, EVANGELISTA AND MARCHI 2000)
Physiological effects.
he muscle undergoes physiological adaptations when prolonged electrostimulation is performed. High amplitude electrostimulation with few repetitions (10-16 contraction cycles) is used when increasing muscle strength and hypertrophy is desired. Electrostimulation applied for over 3 weeks using low amplitude and a high number of repetitions (10 contractions) produces increased endurance and biochemical modifications such as: increased oxidative activity of myoglobin, mitochondria and capillary number, causing the temporary transformation of aphasic (white) muscle filaments to tonic (red) (AGNE, 2004).
Contraindications:
– Recent bone fractures.
– Active bleeding;
– Phlebitis, thrombophlebitis and embolisms
– Cardiac pacemaker:
– Acute or infectious inflammatory processes
– Tumor processes,
– Areas with altered or absent sensation:
– Myopathies that prevent normal muscle contraction;
– Unconsolidated fractures:
– Spasticity;
– Muscular, tendon or ligament lesions
Precautions:
– Do not place electrodes over the area comprising the carotid artery, or the anterolateral region of the neck;
– If the muscle is contracted excessively and suddenly, muscle injury may occur;
– Check that the electrodes are well fitted and with sufficient gel quantity.
Indications:
Muscle relaxation.
Activation of circulation.
Increase and improve the atrophied part.
Regain the sensation of muscle contraction in cases of loss of synesthesia.
Regain the sensation of muscle tone.
Improve physical performance in high-level sports.
Increase and maintain muscle strength.
Improve joint stability.
Postural disorders.
Analgesia (4000Hz).
Minimize muscle flaccidity
PRE and post-surgical.
After immobilization period.
