Respostas de inchaço muscular e atividade eletromiográfica promovidas pelo treinamento de força realizado até a falha muscular e não falha muscular com diferentes números de repetições

Abstract

The manipulation of strength training variables impacts various responses, one of which is muscle activation. With this, increasing the number of repetitions leads to an increase in muscle activation. Surface electromyography (EMG) procedures have been used as the main resource for monitoring muscle activation. However, muscle activation has also been approached through a broader understanding by various authors. One example of this approach is the measurement of the increase in transverse relaxation time (T2). T2 allows for visualizing the fluid entry into the muscle, and this fluid entry increases the cell volume, resulting in muscle swelling. Nevertheless, both muscle activation measurement techniques mentioned have certain restrictions for their use. Thus, measuring muscle swelling through ultrasound imaging could be investigated with the perspective of identifying muscle activation, given that it is possible to use other means to investigate such an outcome. The objective of the present study was to compare the muscle swelling and EMG response between a protocol performed until muscle failure (MF) and five other protocols that would not be conducted until muscle failure (NMF) executed with 10, 20, 30, 40, and 50% fewer repetitions than the MF. Fourteen trained men were selected to perform the MF on the knee extensor bench exercise with 4 sets at 60% 1RM with 2 minutes of interval between sets. Additionally, five other NMF protocols were performed, where a number of repetitions representing a reduction of 10, 20, 30, 40, and 50% in the total number of repetitions completed during each MF set were subtracted. Four repeated-measures one-way ANOVAs were conducted. Two ANOVAs to compare the EMG of the rectus femoris and vastus lateralis muscles, and two ANOVAs to compare the muscle swelling of the respective muscles. For muscle swelling, all protocols differed from each other for both muscles, rectus femoris and vastus lateralis (p < 0.05). As for EMG, for both muscles, the NMF -10, - 20, and -30% protocols did not differ from each other (p > 0.05). The results showed a gradual increase in muscle swelling with an increase in the number of repetitions. As for EMG, small reductions in the number of repetitions do not seem to influencemuscle activation.