A recent contributor wrote (in part), "This would be similar to the modified
or burst modes of TENS when the current CHANGES and thus not allows the body
to accommodate and make the TENS pulses ineffective."
Small correction concerning terminology: The modulated forms of
TENS, as opposed to the so-called "conventional" TENS where current strength
and intensity remain unvarying, are utilized to avoid "habituation", not
"accommodation". Neurophysiologists describe two types of "accommodation":
one concerns the change in pupil diameter and lens convexity when gaze
changes from far to near. The second type of accommodation is the change in
a nerve fiber's threshold that occurs in response to a slowly changing
stimulus pulse. In other words, this accommodation occurs when a single
stimulus does not fulfill the requirement of rising quickly enough. Now,
this is not the same thing that happens when a subject stops feeling
conventional TENS after it has been applied for some time. In this
situation, a continuing, monotonous, non-threatening stimulus, which was
originally perceived, is no longer sensed (or sensed much less). This
diminishing awareness of the stimulus is "habituation", which has a totally
different physiology from "accommodation". To avoid habituation, a repeating
stimulus must be kept "novel", not "monotonous". With TENS devices,
"novelty" is achieved by modulating over time certain aspects of the
stimulus, such as its amplitude, frequency, or pulse durations. For more
details, see Spielholz NI, Nolan MF: Conventional TENS and the Phenomena of
Accommodation, Adaptation, Habituation, and Electrode Polarization. Journal
of Clinical Electrophysiology (the journal of the Clinical Electrophysiology
Section of the APTA), 1995; 7:16-19.
Unfortunately, many manufacturers (who are not physiologists)
continue to advertise the modulating abilities of their units as avoiding
"accommodation", and so perpetuate this misconception among the unwary.
Neil I. Spielholz
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