Magnetotherapy explained - part I
What is Magnetotherapy
Magnetotherapy as well as magnetostimulation is a type of physiotherapy that uses a magnetic field to influence the body. This field may be static (with a use of permanent magnets attached to the body) or time-varying/pulsed (produced by special device).
In 1845 famous scientist Faraday confirmed that every known substance reacts to magnetic field, but in most cases magnetization is not easily visible, like in case with paramagnetic (attracted to magnetic fields) and diamagnetic (repelled from magnetic fields) materials. Other story is with ferromagnetic substances which exhibit strong magnetism in the same direction of the field, when a magnetic field is applied to it.
At the most basic level, all organisms are made of a combination of elements. They contain atoms that combine together to form molecules. Some of them have a magnetic moment which - broadly speaking - means they have a small amount of magnetic energy in them, they may produces a magnetic field and they will be influenced by external magnetic field. The higher the value of magnetic moment, the stronger reaction will be exhibited.
Within the mammal body (human as well as horse or dog) substances known to have a magnetic moment are hemoglobin (protein in red blood cells), some enzymes and free radicals.
Difference between static and pulsed magnetic field
A static magnetic field is one in which no change in the flux density or intensity can be found over the time interval of use or measurement. In time-varying magnetic fields, flux density or intensity changes at one or more frequencies, usually greater than one cycle per second (Hz). The nature of time-varied or pulsed electromagnetic fields (PEMFs), means that they have a frequency in addition to an intensity.
The the Earth's magnetic field at its surface ranges from 25 to 65 μT (microTesla) which is an equivalent to 0.25 to 0.65 Gauss and completely penetrates our body and atmosphere. Therefore any static magnet with field strength below this will not be expected to be active. The magnetic field strength of a static magnet decreases with distance from its surface, and once the field drops to or below the ambient background field strength of Earth, it will be no more effective in the tissues. A time-varying magnetic field is produced by alternating current (AC) electricity. therefore is significantly more dynamic and is able to reach more deeply into the body than static magnetic fields. Unlike static magnetic fields, a time-varying magnetic fields induce electric charge in tissues, creating a cascade of physiologic effects on a sub-cellular level.
Research revealed that technically easy to obtain and therapeutically useful, are those pulsed magnetic fields of frequencies up to 50Hz and intensity range of 1-10 mT (two orders of magnitude grater that natural Earth field).
How pulsed magnetic field influences the body
Among many mechanisms of biophysical interactions between pulsed low-frequency magnetic field and organisms there are a few that are significant for biological effects:
- interactions on uncompensated electron spins - particularly when found within elements of enzymes, it will speed up or slow down the enzymatic reactions, depending on the value of induction of applied magnetic field
- Influence on liquid crystals found within cell membranes (such as adrenal cortex, ovaries, spinal cord and more) will change the properties of the cell membranes, cell organelles and as a consequence - more complex systems
- influence on electric charges moving within the organism. Proper function of many organs depends on biologically-electric circuits, it means that those organs receive information in the form of electric charges. If the charges direction is deviated or changed it will affect the function of specific organs
- change of some physical-chemical properties of water - water is the main component of the body and almost always takes part in cellular activities. Under the influence of external magnetic field water changes its physical properties such as pH, moisturizing, concentration of dissolved gasses (specifically oxygen), rate of crystallization, rate of coagulation or speed of subsidence suspensions
- Induction of gradient potential between cell membranes which results in motion of ions. This process is specially intensive in cardiovascular, lymphatic, nervous, muscular and endocrine system
- Influence on depolarization of cells with intrinsic property of automatism like heart muscle cells or nervous cells. Electric activity of heart, brain and nervous system has a certain frequency imposed by pacemakers, that may be influenced with external magnetic field. According to actual research, low frequency pulsed magnetic field used for therapeutical purposes affects primarily nervous system
- Influence on piezoelectric and magnetostriction structures. Magnetostricion is a property of ferromagnetic substances which causes them to expand or contract in response to a magnetic field. Piezoelectric is the ability of certain materials to generate an electric charge in response to applied mechanical stress. Some substances within mammal body have a piezoelectric abilities like collagen (protein in connective tissues like skin), creatine (protein in muscles) or dentine (component of teeth). For example flexure of the bone will result in the electrochemical gradient between its ends which may lead to current flow. Due to this biological current, the concentration of cells on the more loaded part will be higher, which sometimes may be even seen on radiological images. Therefore the change of shape of certain substances within the body caused by external magnetic field (magnetostrsiction) will influence at some point the end result of body activity.
E. Jakubowska, PhD