## 1 Introduction  
With every scientific progress, numerous methods of physical therapy are being tested and applied, including magnetic therapy. Commonly used devices produce a non-stationary, time-varying, magnetic field. Such devices differ with set parameters, intended use and design. In most cases, the time-varying pulsed magnetic flux is used. To date, the effect of either time-varying or stationary magnetic field remains questionable. Although there is no consensus on whether such devices have a positive impact on biological tissues, there have been scientific studies that indicate a positive influence of induced electric field [1; 2]. Past decades have showed the importance of the low-frequency electromagnetic field as a means in physical treatments used in the field of physical medicine and physiatry, the use of which is also supported by recent findings [3; 4; 5]. Rarely, an alternating current waveform with frequencies from the ELF (extremely low-frequency) band is applied. Whether the biological tissues are conductive or not, the time-varying magnetic field induces an electric field. After the electric field is induced in conductive tissues, the electric charge is carried by charge carriers such as ions. Factors such as the current density of induced electric current have proven to have an effect on tissue treatment because it also has the character of physical energy. The bounce of the induced electrical voltage is caused as a result of a rapid and specifically defined change in time of the high-intensity magnetic field, ergo causing the bounce of induced magnetic electric current (formed in the manipulated/treated tissues). Current densities of the order of tens to hundreds of A\(\cdot\)m\({}^{-2}\) induced in such magnetic field have the required therapeutic ability to affect the sensational and locomotive system [6]. Specific stimulation is achieved by currently available technologies on the medical devices market. Sensory neural pathways are activated due to the application of the magnetic field. This fact causes the sensitivity threshold to be exceeded [7]. Perceived nociception is only minimal due to very specific stimulation, although the inference is very strong in the treated area. Many remedial theories are linked to the evoked difference such as the local trophic effect, a response of neurophysiological mechanisms in segmented and distant polysynaptic reflexes. This fact provides the magnetotherapy (not only) with an analgesic effect, but if applied locally, it also causes the improvement of blood flow and lymphatic functions in treated tissues. In the case of distant application of the magnetic field, treated tissues are affected by the autonomic nervous system network, specifically by the sympathetic nervous system. Nerves restoration in denervated areas and the recovery of damaged or injured tissues is accomplished/facilitated by the inference and its succeeding efference due to the application of the magnetic field [8; 9]. The high-induction magnetic stimulation (HIMS) attracts considerable interest due to its significant impact in a short time, i.e., for the time of the HIMS application procedure. HIMS triggers motor effects through contractions in muscle fibers, without the device touching treated area of muscles [10]. Denervated muscles suffer from atrophies and paralyzes. Still, the stimulation of the motoric system can stop further muscle loss. Recent findings regarding the high-induction magnetic stimulation indicate that it is an effective treatment of functional immobilization initiating the atrophy of particular muscles or whole muscle groups as well as pareses and plegia of organical origins. The high-induction magnetic stimulation has proven to have a great treatment impact on hypertonic muscle spasms and muscle spasticity in general. In fact, HIMS could affect hypertonic muscles to relax and thus, decrease muscle spasticity [1; 4; 11; 12].