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OMNISTIM
®
FX
2
Pro USER MANUAL
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TREATMENT GUIDELINES
Introduction to Medium Frequency Currents
Medium frequency (MF) currents may be described as electrical currents applied to the body for therapeutic
purposes, which fall in the range of 1000 to 10,000 cycles per second (Hz). This is in contrast to low frequency
currents (0.1 to 1000 Hz) such as LVPC and high frequency currents (1 million Hz and beyond), which include
ultrasound, shortwave and microwave diathermy. Medium frequency currents are very advantageous for clinical use
due to their ease of skin penetration at lower intensities.
Normal human skin reacts differently to different frequencies of current. Specifically, there is an inverse
relationship between the frequency of the applied current and the skin’s resistance to it. Medium frequency
alternating currents in the range of 1000 or 5000 Hz provide markedly lower resistance to penetration than low
frequency electrical stimulation commonly used in Transcutaneous Electrical Nerve Stimulation (TENS) and LVPC
stimulation. Medium frequency currents can be used in Bipolar or in Quadripolar Interferential mode for patient
treatment.
With medium frequency currents, the energy of each individual pulse is low providing for stimulation of only one or
two neurons. Since the pulses are coming in very rapid succession, stimulation of surrounding neurons occurs prior
to completion of the previous neurons refractory period. This allows for asynchronous activation of individual
sensory neurons, mimicking the natural physiologic process of the intact nervous system. This is not the case with
low frequency (0.1 to 1000 Hz) stimulators, which are capable of only stimulus synchronous neural activation.
Medium frequency currents provide rapid analgesic effects. This occurs due to rapid depolarization of non-
myelinated pain-transmitting fibers, which block pain transmission, further contributing to high muscle contraction
capabilities.
Additionally, medium frequency currents have been shown to alter the vascular dynamics affecting local and
possibly systemic blood flow to the muscle(s) being stimulated. The unique characteristics of medium frequency
currents, (i.e., higher percent duty cycle, higher average current intensity, and wider pulse widths), can significantly
increase blood flow by altering the metabolic activity of muscles.
PLOT OF IMPEDANCE AS A FUNCTION OF FREQUENCY USING EPIDUCTIVE SYSTEMS