등척성 운동 시 요추의 각도에 따른 중앙주파수와 토크의 특성

Abstract

Fatigue is the decline in force produced as a result of prolonged muscle activity. Localizedmuscle fatigue can be identified by a shift toward low in the frequency components of the EMGsignal, typically represented by a fall in the median frequency. Previous studies show that ashortened muscle develops a higher fatigue than elongated muscles. The purpose of this studywas to investigate the time-related change of median frequency and torque during maximalisometric back extension exercises at different exercise angles (0°, 12°, 36°, 72°). Twentyhealthy subjects (mean age = 24.35 ± 2.70) were evaluated in this study. Median frequencywas extracted from the EMG signals by fast Fourier transform (FFT). Initial median frequencyand the slope of median frequency change over time were computed from linear regression analysis. Pearson's product moment correlation was used to quantify the relationship between slope of medianfrequency and torque. The results were as follows: 1) Significant differences in y-intercepts oftorque regression equation with respect to exercise angle were shown. However, there were nodifferences in the slopes of the median frequency and torque, and y intercept of the medianfrequency among exercise angles. 2) There was no significant correlation between slope ofmedian frequency and torque. 3) But there was moderate correlation between median frequencyand torque at each exercise angle. In conclusion, the exercise angle during maximal isometricback extension exercise is not a direct effect on slope of median frequency and torque. Butresults showed that median frequency and torque shift were highly correlated in all subjects.