Treinamento físico com restrição de fluxo sanguíneo: aspectos fisiológicos e metodológicos relacionados a prescrição do método

Abstract

Blood flow restriction (BFR) training has been suggested as a viable alternative for people with limitations to high-load training, due to its ability to induce significant muscular adaptations using lighter loads. However, despite extensive investigation of its effects, the literature presents controversial evidence and significant gaps in certain outcomes. This doctoral thesis aimed to analyze the effects of BFR physical training, exploring methodological factors that may contribute to the observed divergences. Seven studies were conducted and presented in this thesis. The first study consisted of a scoping review on the effects of high-frequency (>4 days/week) and short-term (≤3 weeks) BFR training, including 22 studies that mainly investigated the effects on muscle strength and hypertrophy. Results indicated significant increases in both strength and muscle hypertrophy after 1-3 weeks of BFR training. However, under conditions of muscle failure, the potential for prolonged decrease in strength and muscle atrophy has been observed. Subsequent studies were systematic reviews with meta-analyses. The second study compared the effect of low-load resistance training with BFR versus high-load resistance training on muscular hypertrophy, focusing on the different repetition schemes adopted in BFR training. The meta-analysis revealed no significant differences between conditions, even after stratification by repetition scheme. The third study investigated the effect of pressure applied in low-load resistance exercise on muscle fatigue and myoelectric activity, identifying that higher pressures increased fatigue, especially in exercises with lighter loads (≤20% of 1 repetition maximum). The fourth study was a scoping review that explored variables that influence arterial occlusion pressure (AOP), highlighting factors such as body position and cuff characteristics and positioning. The fifth study was a cross-sectional study comparing different cuffs and body positions in measuring AOP, concluding that cuff size and body position significantly impact the determination of AOP. The sixth study was a systematic review and meta-analysis that evaluated perceived exertion and discomfort during low-load resistance exercise with BFR compared to traditional resistance exercise, finding significant differences in perceived exertion and discomfort depending on the repetition scheme adopted. Finally, the seventh study was a randomized crossover experimental trial that compared walking with BFR with highintensity interval exercise in healthy untrained individuals, analyzing psychophysiological responses such as affect, future intention to perform the exercise, lactate concentrations and heart rate. The results indicated that high-intensity interval exercise generated greater physiological stress and affective responses compared to walking with BFR. These studies provide a comprehensive view of the effects of BFR training and highlight the importance of considering methodological factors in interpreting results and practical application of this promising method.