Efeito da vibração mecânica localizada sobre variáveis de força e eletromiografia de membros superiores de lutadores de jiu-jitsu

Abstract

Mechanical vibration warm-up protocols may be able to promote neuromuscular changes that may contribute to jiu-jitsu acute muscle strength performance. Objective: To verify whether a warm-up performed with mechanical vibration will promote greater muscle activation and isometric pulling force performance compared to a warm-up performed without mechanical vibration. Methodology: The participants are experienced in jiu-jitsu. They performed three sessions, separated by 48 hours. In the first session, the volunteers were familiarized with the specific warm-up protocol, with and without mechanical vibration, and with the isometric pull test (PI). On the second and third visits, the volunteers performed the specific warm-up, four sets of 15 seconds performing to the isometric rowing exercise, and a 30-second interval between sets. This warm-up was executed in a moment without mechanical vibration (V00) and another moment with vibration at a frequency of 26Hz (V26). Four minutes after the end of the exercise, the PI test was conducted. During the warm-up and the test, the electrical activity (EMG) of the Biceps Brachii (BB) and Latissimo Dorsal (LD) muscles was captured. EMG was assessed using Root Mean Square (RMS) and Median Frequency (FMedian). Muscle strength was assessed using the variables Maximum Strength (FMax), Force Production Rate (TPF), Average Strength (FMED) and Fatigue Index (IF). EMG data was normalized from data collected in the PI test at the pre-warming moment. The absolute (DA) and relative (DR) delta of the muscle strength variables were evaluated. Test-T Student compared the DA and DR between situations V00 and V26. Anova Two-Way was used to compare the RMS and FMedian in the specific warm-up (AE) and in the PI test, between situations V00 and V26, and between pre and post moments. As well as, to compare muscle strength variables between situations V00 and V26 and between pre- and post-warm-up moments. In case of significant differences, the post-hoc test indicated by the software was applied. The significance level adopted was p<0.05. Results: DA and DR of FMAX (DA p = 0.05; DR p = 0.02) and FMED (DA p = 0.02; DR p = 0.02) were higher in situation V26. FMAX (p=0.002) and FMED (p=0.001) in the PI test interaction between situation and moment was presented. RMS of the LD muscle during warm-up was higher in V26 compared to V00 (p=0.045) and presented the main situation effect (p= 0.017). LD RMS in the PI test was lower in the V26 situation compared to V00 (p=0.008). Conclusion: Vibration warm-up increased the performance of FMAX and FMED with the reduction in the RMS of the LD.