Efeito agudo da vibração mecânica sobre o desempenho de resistência de Força Dinâmica e EMG de músculos dos membros superiores em praticantes de treinamento de força

Abstract

This study aims to investigate the acute effect of mechanical vibration on strength performance and electromyographic activity (EMG) of the Latissimo Dorsal (LD) and Biceps Brachial muscles in a maximum repetitions test in resistance training practitioners. METHODOLOGY: Eighteen volunteers who practice resistance training participated in the research. The research was divided into two stages. Stage 1: Obtaining anthropometric measurements, anamnesis, familiarization with the isometric rowing test (IR) and the dynamic rowing exercise (DR). Stage 2: Tthe volunteers performed 2 experimental sessions with 48 hours apart. The volunteers performed the 6s IR with strength and electromiograhpic (EMG) of brachial biceps (BB) and latissimus dorsi (LD) measurements. Two minutes after the IR test, the volunteers performed the DR, with 70% of the maximum strength performed in the IR test. In an experimental session, the DR test was performed with vibration of 26Hz and 3mm (CV), and in the other session, the DR test was performed without vibration (SV). During the DR test, volunteers should perform the maximal number of repetitions until failure, maintaining a cadence of 1.7s in the concentric phase and 1.7s in the eccentric phase. There was measurement of the EMG of LD and BB throughout the test. The EMG data from the DR test were normalized by the data from the IR test. For statistical analysis, the paired t test was applied to compare the maximal strength in IR, and the maximal number of repetitions, EMG of BB and LD between days CV and SV. Also, a Pearson Correlation test was performed for the maximal strength data obtained in the IR between days CV and SV. The significance level adopted was p<0.05. RESULTS: There was no difference in maximal strength performance in the IR test between CV and SV (p=0.15) and the correlation was high (r=0.70), showing that the volunteers started the two experimental sessions with similar performance. The maximal number of repetitions in the DR test on the CV day (35±7.97) was higher than on the SV day (29.12±7.98) (p=0.01). Also, the median frequency of EMG was lower on day CV compared to day SV (p=0.04) for the BB. CONCLUSION: The results show that localized mechanical vibration increases the acute performance of dynamic strength resistance, and that there is a reduction in the median of the EMG frequency, without changing the signal intensity (RMS).