Abstract

The demand for objective and quantitative assessment of muscle power which can replaces the manual muscle test is increasing. The purpose of this study is to determine the usefulness of total spectral power(P_EMG) of individual muscle as one of the objective spectral parameters, in quantitification of muscle power. From 17 normal male without neuromuscular dysfunction, motor unit action potentials(MUAPs) of flexor muscle group of the thumb of the dominant hand were obtained. The surface electrode was used in 11 subjects and the needle electrode was in 6 subjects. The changes of P_EMG and spectral power according to frequency components were calculated during increasing force of isometric muscle contraction by power spectral analysis of MUAPs signal. The following results were obtained.

1) There was a linear relationship between P_EMG and isometric ramp muscle contraction with surface(F-ratio=363.8, P<0.01) and with needle(F-ratio=12.83, P< 0.01) electrodes. And also a quadratic relationship was noted with surface(F-ratio=6.62, P<0.05) electrode.

2) There was a linear relationship between 20-80 Hz frequency spectral power and isometric muscle contraction with surface(F-ratio=196.9, P<0.01) and with needle(F-ratio=13.42, P<0.01) electrodes. And also a quadratic relationship was noted with surface(F-ratio=5.20, P<0.05) electrode.

3) There was a linear relationship between 81-200 Hz frequency spectral power and isometric muscle contraction with surface(F-ratio=148.43, P<0.01) and with needle(F-ratio=10.55, P<0.01) electrodes.

4) There was no significant correlation between pinch power in MVC(maximal voluntary contraction) and total spectral power in 87.5-100% of MVC with surface(r=-0.215) and needle(r=0.384) electrodes. Above results suggest that the P_EMG, especially when measured with surface electrode, will be useful in quantitification of muscle power.

• Keywords: Total spectral power, Power spectrum, Total spectral power, Muscle power, Quantitative assessment