Interferential currents are medium-frequency currents. Their application results in muscle contraction, analgesic effect, and improvement of nutritional processes in tissues.
Parameters and waveform
The basic frequency for interferential currents is called a subcarrier. Its value in the case of simple devices is 4 kHz. Modern devices allow you to change this value in the range from 2kHz to 10kHz. In order to obtain interference, the basic frequency is modulated by a low frequency values from 2 Hz to 100 Hz.
To prevent adaptation of muscles and not only muscles, low-frequency modulation in the range of 0 Hz to 200 Hz is applied during the treatment procedure. This modulation is often marked as FM (frequency modulation), it is also sometimes called the deviation. For example, set parameters: 100Hz of basic frequency and 200Hz of deviation value causes that the low frequency modulation will vary in the range from 100Hz to 300Hz (200Hz + 100Hz) according to the frequency modulation of the set training program. Frequency modulation training programs are called FM1 … etc. Sample modulation Program FM 2-3-2-4 means that the frequency will increase by the value of deviation in time 2s, it will remain high for 3s and after 2s of falling phase the waveform will be modulated by a frequency without deviation within 4s. In the case of interferential currents in addition to FM modulation also AM amplitude modulation is applied. In this case the principle of modulation is to change the amplitude according to the AM selected program.
Application:
Interferential currents demonstrate the following effects on the human body:
- analgesic effect
- stimulation of muscles to contraction
- vasodilation of blood vessels
- improvement of nutrition and tissue metabolism processes
- impact on the autonomic nervous system
Effects:
Medium-frequency currents penetrate deeper into the tissue due to its capacitive nature. Therapeutic effects of interferential currents are similar to the low frequency currents, but for some reasons this type of current is more beneficial for the patient.
| Frequency | Effects |
| 0-10Hz | Stimulating effect, results in a contraction of denervated muscles |
| 25-50Hz | Improves peripheral blood circulation, stimulates muscles to contraction |
| 50-100Hz | Induces an analgesic effect, and also improves tissue tropism. Apply the intensity above the sensory threshold to achieve the effect of vibration. |
| 90-100Hz | Analgesic effect which reduces the tension of the sympathetic nervous system. |
| 0-100Hz | Generalized influence of all of these effects. |
An important advantage of interferential currents is the impact on deep tissue groups. This happens due to the high carrier frequency. The capacitive nature of the tissue makes that the higher frequencies penetrate deeper. Another advantage is a better tolerance of higher doses than in the case of low frequency currents.
Interferential currents – a waveform in two channels shifted in phase by 90 °.
Method of performing treatment:
Carrying out the treatment procedure with the use of interferential currents there is no need to worry about the application of pads insulating the electrode from the patient’s skin as the interferential current is symmetric and it does not introduce ions in the tissue. In this case, primers are applied only due to the hygiene reasons. Improved tolerance of higher intensities allows for the use of smaller electrodes, which in turn enables for the use of Vaco type units which greatly facilitate the operation. Thanks to this we can avoid the application of viscose covers which are difficult to dry and long velcro belts.
Interferential currents demonstrate the following effects on the human body: Normal 0 21 false false false PL X-NONE X-NONE