SKELETAL MUSCLE FIBER TYPE BASED ON HIGH-DENSITY SURFACE ELECTROMYOGRAPHY DECOMPOSITION

Abstract

Background: The types of skeletal muscle fibers have important reference value in the recruitment of exercise units and selection of sports materials. In this study, we explored a non-invasive method to determine the type of skeletal muscle fibers through the study of high-density surface electromyography (HD-sEMG). Methods: Twenty-one male students from Beijing Sport University were selected to perform the maximum voluntary contraction on the isokinetic dynamometer. In the test, the subjects exercised to fatigue with 70% maximum voluntary contraction (MVC), simultaneously performed ultrasonic and surface electromyography tests on the lateral thigh muscle, and then took muscle biopsy samples to determine the type of muscle fibers after marking the same position. The stepwise linear regression analysis was carried out between the electromyography related indexes and the percentage of muscle fiber types to establish the regression equation for estimating the percentage of muscle fiber types of lateral thigh muscle. Results: (1) In the process from 70% MVC to fatigue, the time domain index of HD-sEMG signal showed a linear upward trend, while the frequency domain index showed a linear downward trend. (2) The percentage of fast muscle fibers was significantly correlated with electromyography, muscle strength and duration(P<0.05). (3) The sEMG prediction regression equation of fast muscle fiber percentage is: Y=42.569+0.435 AEMG _slope-0.137 AEMG _% +6.83 MPF _slope-0.157 MPF _%-0.093 Mass/MVC-0.042 Duration+0.111 MVC_70%. Conclusion: The percentage of skeletal muscle fiber types can be indirectly determined by HD-sEMG without injury.