Autonomical and Hemodynamic Repercussions on Excentric Resistance in Different Intensities Associated With Blood Flow Restriction: a Randomized Clinical Trial

Introduction: Studies on resistance training (RT) associated with blood flow restriction (BFR) have emerged as an alternative method of gaining strength and hypertrophy; however, the cardiovascular and autonomic repercussion of BFR at different intensities is unknown. Thus, it becomes relevant to investigate this type of training in post-exercise. Objective: investigate and compare autonomic and hemodynamic responses of acute eccentric RT with different intensities associated or not to BFR in healthy youngsters. Method: This is a randomized clinical trial including 60 healthy men aged 18-35 years, divided into four groups according to exercise intensity and BFR: 80% without BFR, 40% without BFR, 80% with BFR and 40% with BFR. Exercise intensity will be determined by the peak of excentric torque on the dinamometer isokinetic method and by the BFR, as being 40% of the intensity required for the complete examination of the blood flow evaluated by Doppler. Participants will do an eccentric femoral quadriceps muscle exercise session on the isokinetic dynamometer according to the previously randomized group. For recovery analyzes, the recovery heart rate (HRR) in the 1st (HRR1) and 2nd (HRR2) minute, rMSSD of 30 seconds, the hemodynamic parameters (heart rate, systolic and diastolic blood pressure, respiratory rate, peripheral oxygen saturation and rate pressure product) and heart rate variability (HRV) indices analyzed in the time domain (mean HR, rMSSD and SDNN), frequency domain (LF and HF [nu and ms2]) and Poincaré plot (SD1 and SD2). The analysis will be occur on baseline, immediately e after the excentric exercise and in the post exercise period for 60 minutes. Descriptive statistics method and comparison of HRV indices and hemodynamic parameters between moments and groups will be performed with the aid of the analysis of variance technique for the repetitive measures model without the schema of two sets of tests to follow . The level of significance will be p <0.05.