The purpose of this work was to register the electromyography data of the muscles brachialis, biceps brachii long portion, biceps brachii short portion and brachioradialis in the movements of elbow flexion, in the Larry Scott bench, in supination and pronation positions, in weightlifting trained subjects. Ten male right-handed subjects were selected, with at least one-year experience in weightlifting exercises, without previous neuromuscular diseases, age between 21 and 26 years. After taking the Maximum Load (M.L.) test, or a maximum repetition, we had the percent pattern to establish the loads used in the tests, which was 80%0 of the M. L. For the electromyography records was used a six-channel electromyography (lynx) and the AqDados software in four different moments for each subject: an isometric phase lasting five seconds in supination (1), keeping a 90 degrees angle between the arm and forearm; another one in isometric pronation (2); ten repetitions lasting fifty seconds in supination (3); and ten repetitions in pronation (4). The results of the normalization showed a level of similar activation between the involved muscles in one same moment, as much in supination as in pronation. From the analysis of variance ANOVA, having as level of significance p < 0,05, concludes that it did not have significant difference in the performance of these muscles. When compared between itself all the values of p were bigger than 0,05. Of this form we can perceive a joint action of all the flexion muscle of the elbow to resist the load imposed during the effort.4749-54