Abstract of article "Short-term repeatability of parameters extracted from radial displacement of muscle belly"

KRIŽAJ Dejan, ŠIMUNIČ Boštjan, ŽAGAR Tomaž. Short-term repeatability of parameters extracted from radial displacement of muscle belly. Journal of Electromyography and Kinesiology., 2008, vol. 18, str. 645–651

Abstract

This study was made in order to analyse the short-term repeatability of the parameters extracted from radial muscle belly response on a stimulation pulse. The method is based on a prefixed tension of a displacement sensor tip to the muscle which was developed for noninvasive and selective evaluation of skeletal muscle contraction properties. Statistical evaluation of five extracted parameters from the measured displacement was made: maximal displacement, delay time, contraction time, sustain time and half relaxation time. Between stimulation pulses, sufficient time was left in order to reduce the effect of muscle fatigue. Furthermore 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. As measures of short-term repeatability and accuracy (precision) of the measurements intra-class correlation coefficient (ICC) and normalized squared error (NSEM) were used, while fatigue rate was evaluated using area ratio fatigue index and normalized slope. Highly repeatability of all five measured parameters have been found (ICC from 0.86 to 0.98) and furthermore all five measured parameters can be measured with high precision (NSEM from 0.43 to 1.93). Largest influence to muscle fatigue rate was shown by maximal displacement and half relaxation time.