LSI System II User Manual

Introduction
Principles of Interferential Therapy
Interferential therapy was rst developed by Dr. Hans Nemec of Vienna, Austria in the early 1950s.
Its use has grown dramatically since its introduction in the United States in the 1970s.
Three prerequisites are necessary for interferential current therapy: a) medium frequency current (1000
to 10,000 Hz), b) two independent current generators and c) alternating current. By crossing two currents
within the tissue, they “interfere” with each other and form a “beat frequency” in the deeper tissue.
It has been established that by increasing the frequency of any alternating current, the skin resistance
(measured in ohms) is reduced. (see g. 1)
Burton and Maurer, 1974. Pain Suppression by Transcutaneous Electronic Stimulation. IEEE Transaction on Biomedical Engineering.
Interferential current therapy may be produced by two different methods. They are commonly referred to
as the “Frequency Difference” method and the “Premodulated” method. The LSI System II unit is capable
of producing interferential current through either of these methods.
8
Interferential therapy was first developed by Dr. Hans Nemec of Vienna, Austria in the early 1950s.
Its use has grown dramatically since its introduction in the United States in the 1970s.
Three prerequisites are necessary for interferential current therapy: a) medium frequency current (1000 to
10,000 Hz), b) two independent current generators and c) alternating current. By crossing two currents
within the tissue, they “interfere” with each other and form a “beat frequency” in the deeper tissue.
It has been established that by increasing the frequency of any alternating current, the skin resistance
(measured in ohms) is reduced. (see fig. 1)
Burton and Maurer, 1974. Pain Suppression by Transcutaneous Electronic Stimulation. IEEE Transaction
on Biomedical Engineering.
Interferential current therapy may be produced by two different methods. They are commonly referred to as
the “Frequency Difference” method and the “Premodulated” method. The LSI System II unit is capable of pro-
ducing interferential current through either of these methods.
1
50 K
20K
10K
5K
2K
1K
500
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Introduction
Principles of Interferential Therapy
Frequency – (Hz)
Impedance as a function of frequency
Fig. 1
Series Equivalent Resistance (ohms)

LSI System II Specifications

General

Brand	LSI
Model	System II
Category	Test Equipment
Language	English