Tempo sob tensão, atividade eletromiográfica e lactato em repetições máximas múltiplas nos exercícios supino reto e agachamento

Abstract

INTRODUCTION: The volume and intensity of the training can be obtained by the total number of repetitions completed during a specific period, known as time under tension (TUT). Therefore, the aim of the present study is to verify the association between TUT, electromyographic activity (EMG) and lactate levels (LAC) in multiple repetitions maximum (RM) in bench press (BP) and squat (SQ) exercises. METHODS: The sample consisted of 21 males (age: 19.09 ± 0.30 years; body mass: 67.89 ± 6.6 kg; fat percentage: 7.99 ± 1.61), divided into bench press group (n = 11), and squat group (n = 10). The TUT for 8, 10 and 12RM was verified through the cinemetry. After 48 hours of the RM test, the participants performed the exercises with the mean TUT of the group and the load obtained in the tests. We verified the number of repetitions performed, EMG and LAC. RESULTS: The ANOVA revealed significant differences in all protocols in the TUT and LAC variables (p < 0.05) in ascending order to the number of repetitions (8<10<12RM). In the BP, the EMG activity of the pectoralis major muscles, clavicular part (CP) and sternocostal part (SP) presented higher EMG signal for 12RM compared to the 8 and 10RM protocol. However, the deltoid and triceps muscles did not show any difference in the EMG response. In SQ, we verified a significant reduction of the rectus femoris activation for the 10 and 12RM protocols, as well as the vastus lateral (VL) activation for the 8 and 12RM protocols. Pearson's correlation test showed positive associations between the TUT and LAC variables in BP (r = 0.665; p < 0.001) and SQ (r = 0.742; p < 0.001). There were negative associations between SP muscle activity and overload (r = - 0.344; p = 0.005) and between CP and TUT (r = - 0.444; p = 0.010). Positive associations between SP with TUT (r = 0.591; p < 0.001) and with LAC (r = 0.416; p = 0.016) were also verified. In SQ, VL presented negative correlation with TUT (r = - 0.495; p = 0.005) and with LAC (r = - 0.428; p = 0.018). CONCLUSION: We observed association for the TUT and LAC variables. This situation was also found in the EMG for CP and SP muscles in BP, and VL in SQ. Thus, the control of the volume/intensity ratio and the prescription in the repetition ranges of the exercises proposed by the present study can be performed based on the TUT