Time-Frequency Analysis of Electromyographic Signal for the Biceps Brachii during Ramp Movements

Abstract

To understand the neuromuscular activation patterns of the elbow flexor under different loads during weight training movement, we examined the electromyography (EMG) signal induced under different loads with ramp movement. Twenty-one young male physical education students or collegiate sport players voluntarily participated in this study. A force transducer, goniometer, and electromyographic system were used simultaneously with a data acquisition (DAQ) system to collect the signals for force, elbow angular displacement and EMG. The obtained data were analyzed by SPSS and simple regression was used to test the relationship between loads and EMG amplitude as well as the relationship between loads and EMG median frequency (MDF). The significance level was set at .05. The results revealed that the EMG amplitudes showed a linear positive correlation with the loads. On the other hand, the EMG MDF remained stable despite an increase in the loads. Therefore, the variation in EMG MDF was independent of the variation in the loads. These findings indicated that the linear relationship between activation pattern and load during ramp movement is attributable to fiber recruitment rather than firing frequency.