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Introduction
Biofeedback is a rapidly developing scientific field that has grown
out of advances in physiology, psychology and electronics.
Ordinarily, we are unaware of the subtle internal body activities that
are part of our everyday lives. Biofeedback uses sensitive
electronics to detect and amplify theses activities in order to bring
them to awareness. By allowing us to observe these activities,
biofeedback also allows us to learn to modify them. Since we are
immediately aware of the outcome of our attempts, we can
gradually learn to produce the results we desire.
Muscles go through a wide range of activity. Normally, we are only
aware of the muscle activity associated with movement, such as
occurs in swinging a tennis racket. Yet much muscle activity
produces no visible movement and, as a result, goes unnoticed.
EMG (electromyographic) activity is a measure of the electrical
activity in the muscles. Since the electrical activity of the muscle
increases when the muscle is tensed and decreases when it is
relaxed, EMG biofeedback can provide information about the state
of relaxation or tension of our muscles.
Our muscles respond to threatening, stressful situations with large
increases in tension. This response is part of an old reflex left over
from a time when one had to either fight or flee from a stressful
situation in order to survive. Today, fighting or running isn't
generally appropriate. So, in most stressful situations, there is
increased muscle tension, which cannot be dissipated by fighting or
fleeing. If this high tension continues, muscle fatigue, soreness, or
even pain may result.
