ORIGINAL
PAPERS – abstract
Short-term
repeatability of parameters extracted from radial displacement of
muscle belly Dejan
Križaj, Boštjan Šimunič, Tomaž Žagar
Faculty
of Electrical Engineering, University of Ljubljana, Slovenia
Abstract The
aim of this study is to analyze the short-term repeatability of the
parameters extracted from radial muscle belly response on a
stimulation pulse. The method uses a prefixed tension of a
displacement sensor tip to the muscle and is being developed for
noninvasive and selective evaluation of skeletal muscle contraction
properties. Five parameters were extracted and statistically
evaluated from the measured displacement: maximal displacement, delay
time, contraction time, sustains time and half relaxation time. Care
has been taken to leave sufficient time between stimulation pulses in
order to reduce the effect of muscle fatigue and a constant
pre-tension was assured by controlled step motor in consecutive
measurement by withdrawal and anew placement of the sensor to the
muscle belly after each measurement. Intra-class correlation
coefficient (ICC) and normalized squared error (NSEM) were used as
measures of short-term repeatability and accuracy (precision) of the
measurements while fatigue rate was evaluated using area-ratio
fatigue index and normalized slope. All five measured parameters have
been found highly repeatable (ICC from 0.86 to 0.98) and can be
measured with high precision (NSEM from 0.43 to 1.93). Maximal
displacement and half relaxation time show largest influence to
muscle fatigue rate and are also expected to be the best measure of
the fatigue rate. This investigation should serve as an initial study
of repeatability of the presented method that should help in
subsequent investigations and use of the method. Key
words: tensiomyography,
mechanomyography
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