Summary
Maximum amplitude tolerance (MAT) has been known as a primary factor determining
the depth of electrical current penetration. However, the effect of varying
transcutaneous electrical stimulation (TES) parameters on MAT and discomfort level is
poorly understood. Furthermore, limited information exists regarding the
biopsychological factors that may impact MAT and discomfort. The primary aims of this
study were to compare the effects TES protocol with varying levels of pulse duration
(300 μs vs 700 μs) and frequency (30 Hz vs 80 Hz) on the MAT and
discomfort in healthy older adults. The exploratory aim of this study was to examine
relationships between submental adipose tissue thickness, pain sensitivity and gender
with MAT and discomfort. Twenty-four healthy older adults participated in this study.
Transcutaneous electrical stimulation was delivered to the submental region. Maximum
amplitude tolerance and discomfort were measured for each condition. Furthermore,
submental adipose tissue thickness and pain sensitivity were measured for each subject.
Maximum amplitude tolerance was significantly increased for the TES protocols with
short-pulse duration [F (3, 69) = 38.695, P < .0001]. Discomfort
was similar across different TES protocols. Submental adipose tissue thickness
(r = .30, P < .003) and pain sensitivity (r
= −.43, P < .0001) were related to MAT. Pain sensitivity
rating was also related to discomfort (r = .45, P
< .0001). In conclusion, using TES protocols with short-pulse duration may
increase the MAT. Higher amplitude stimulation may increase the impact on deep
swallowing muscles. In addition, submental adipose tissue thickness and pain sensitivity
are potential biopsychological factors that may affect MAT and discomfort.