Muscle Effects

Acta Physiol Pharmacol Bulg. 2001;26(1-2):37-40.

Long-lasting (fatiguing) activity of isolated muscle fibres influenced by microwave electromagnetic field.

Radicheva N, Mileva K, Georgieva B, Kristev I.

Institute of Biophysics, Bulgarian Academy of Sciences, Sofia.


The study aims to clarify the effect of exposure to microwave electromagnetic field (MMW) on muscle fibre fatigue. Repetitive stimulation with interstimulus interval of 200 ms was applied on isolated frog muscle fibre to evoke intracellular action potentials and twitch contractions. After their recording muscle fibre preparation was moved in a Petri dish with radius of 28 mm on open air for one hour exposure to continuous MMW with frequency of 2.45 GHz and power density of 20 mW/cm2. Then it was again moved in the chamber with non irradiated Ringer’s solution at controlled temperature for the repeated records. After MMW exposure the changes in amplitude and time parameters characterizing fatigue were attenuated and delayed vs. controls. The twitch amplitude curve described an drastic fall in the first 5 sec followed by an increase and next decrease. MMW (2.45 GHz) have a specific, non-thermal influence on muscle fibre activity resulting in some resistance to fatigue.

Am J Phys Med Rehabil. 1994 Jul-Aug;73(4):275-9.

Tardy effect of neurogenic muscular atrophy by magnetic stimulation.

Chang CW, Lien IN.

Department of Physical Medicine and Rehabilitation, National Taiwan University School of Medicine, Taipei, Republic of China.

The influence of pulsed magnetic stimulation on denervated muscles was investigated in this study. Of 24 rats divided into three groups for experiment, 8 rats served as control; 16 rats with bilaterally severed sciatic nerves were divided into two groups for different modes of stimulation. Magnetic stimulation with a high power output that induced an intensive contraction of muscle was applied at one side-denervated gastrocnemius muscle for 1 mo in a group of rats; electric stimulation with high intensity at 6 Hz frequency and 1-ms pulse duration served as a contrast in the other group. Muscular weight, volume, fiber diameter and percentage of fiber types were measured after the experiment. A significant retardation of weight loss in denervated muscles via magnetic stimulation (P < 0.05) was confirmed by observed results. Type II fiber atrophy was retarded in denervated muscles by magnetic stimulation as well as in denervated muscles via electric stimulation. Magnetic stimulation, used as a method that induces muscular activity, was verified in this study as being capable of retarding denervated muscular atrophy. Its benefits of painless stimulation as well as deeply activated muscular contraction could be expected to function as a new model for rehabilitation of paralyzed muscles.