FREQUENCY CHARACTERISTICS IN ISOMETRIC MUSCULAR CONTRACTIONS FROM CORRELATION FUNCTION AND FOURIER ANALYSIS OF SURFACE ELECTROMYOGRAM / 体力科学

ABSTRACT

Analyses of correlation function and Fourier transformation are one of the important tools in the investigation of biological phenomena. Since the method of these analyses had been applied for interpretation of surface electromyogram, isometric muscular contractions had been estimated easily and accurately. Reliability and validity of measured values had been acquired by the assistance of the electro-computer and statistology. On the assumption that generated processes of surface electromyogram of arm and leg were 1) probabilistic 2) stationary and 3) Gaussian, power spectrums of probability density functions of measured values, were calculated in X-Y charts.<BR>As the results of the expeliment, following points were revealed.<BR>1. For the estimation of surface electromyogram upon muscular isometric contractions, these analytical methods should be applied for physical fitness researches with reliability and validity of the results.<BR>2. Upon the isometric muscular contraction, main discharge-frequency among surface electromyogram were existed in two bands of about 20 Hz and 90 Hz peaks.<BR>3. In proportion to intensities of load (Kg), magnitude of the agonist's discharge was increased in the frequency-band of 90 Hz, and that of the antagonist's discharge also was increased in the frequency-band of 20 Hz.<BR>4. According to these results, it was assumed that frequency-band of about 20 Hz would be corresponded with tonic muscular discharge and that of about 90 Hz would be equivalent to phasic muscular discharge.<BR>5. The longer time of muscular contractions sustained, the wider the frequency-band of about 90 Hz became on account of mixed and interfered discharges of neighboring muscle groups.