Variation in Neuromuscular Activation of Loaded Explosive Movement

Abstract

To understand the neuromuscular activation pattern of the elbow flexor muscle under different loads during explosive movements, the electromyography (EMG) signals were induced under different loads with movement. Twenty-one young male physical education students or collegiate sport players were voluntarily participated in this study. Each subject performed fast concentric movement of the elbow flexor muscle under 15%, 30%, 45%, 60%, 75%, 90%, and 105% of maximal voluntary contraction. A loadcell, goniometer and the Biovision EMG system were used to collect the signals for force, elbow angular displacement and EMG. After the data were processed, the SPSS software was used to calculate the values of the parameters, and simple regression was used to determine 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 demonstrated that the EMG amplitudes of explosive movement remained high because of the maximal effort exerted when the loads were changed. In other words, the diversity of EMG amplitudes was independent of the variation in the loads. On the other hand, EMG MDF showed a linear positive correlation with load. These results suggest that explosive movement with a heavy load might be suitable for power training to improve the rate of force development by enhancing the efficiency of activation frequency, even though its movement velocity was not higher than that of explosive movement with a light load.