Ultrasounds are high frequency sound vibrations that cannot be perceived by the human ear. In the therapeutic field, the application of ultrasounds to human tissue provides a cellular and inter-cellular high frequency massaging action. Also, ultrasounds can also be used under water. The head is immersed in water along with the area to be treated. The tissues irradiated by ultrasounds vibrate in turn, resulting in energy being released, which produces heat. This summarizes the biological effects of ultrasounds - a mechanical and diathermal effect:
- The Mechanical effect: is produced by the rhythmic compression and decompression of tissue. The particles in tissue covered by the vibrating band are all activated alternately, with the same acceleration and speed.
- The Diathermal mechanism: with possible biological effects begins to be possible at energy levels of 1 Watt/cm². As the sound is propagated through the tissues it is absorbed and converted into heat. The distribution of the temperature produced by the ultrasound in the tissues, is unique among the various forms of deep heating: in fact, it brings about an increase in temperature that is relatively small on the surface of the tissue and is more likely to penetrate the muscles and soft tissue than diathermia produced by microwaves or short circuits.
The therapeutic effects of ultrasounds are partly due to the increase in temperature. These take the form of analgesia, relaxation of the muscles, and a fibrolytic and trophic effect.
- Analgesia - The analgesic effect is due to the heat, and probably also the direct action of the ultrasounds on the sensitive nerve endings.
- Relaxation of contracted muscles - Relaxation of contracted muscles is associated with the thermal effect and micro massaging of the tissue, induced by the passage of the ultrasounds.
- Fibrolytic effect - Oscillation of the tissue particles, caused by the ultrasounds, results in disruption of the collagen fibers in fibrous and sclerotized tissue.
- Trophic effect - Vasodilation, which results from a rise in temperature, facilitates the removal of catabolites and puts nutritive substances and oxygen into the tissue. In this way ultrasounds improve trophism of the tissue, facilitate repair of tissue damage and speed up resolution of inflammatory processes.