RELATIONSHIP BETWEEN WORKLOAD AND NEUROMUSCULAR ACTIVITY IN THE BENCH PRESS EXERCISE

Objective: To investigate the relationship between strength and electromyographic (EMG) signal in different intensities in the bench press exercise. Methods: Eleven healthy resistance trained men (22.8 ± 3.5) participated into the present study. Maximal isometric strength was determined in the bench press exercise using a load cell. Muscle activation was assessed using surface elec- tromyography (EMG) signals from the muscles pectoralis major, anterior deltoid and posterior deltoid at intensities ranging to 60-90% of maximal voluntary contraction (MVC), in the bench press exercise. This procedure allowed the analysis of the strength/EMG relationship. Results: In all muscles assessed, there were significant differences in the normalized muscle activation between the intensities of 60 and 70% of the MVC, as well as between 70 and 80% (P<0.05), while there were no differences between 80 and 90% of MVC. In addition, there were significant correlations between strength and EMG signals for the muscles pectoralis major (r=0.43, P=0.04), anterior deltoid (r=0.52, P=0.01), and posterior deltoid (r=0.32, P=0.046). Conclusions: These results suggest that levels of muscle activation near to maximal are obtained at the intensity of 80 of MVC and no additional motor unit recruitment are achieved at 90% of MVC.