NÁDIA FAGUNDES GARCIA EFEITO DO TREINAMENTO DE FORÇA COM RESTRIÇÃO DE FLUXO SANGUÍNEO NA REATIVIDADE DA AORTA ABDOMINAL EM RATOS WISTAR

GARCIA, Nádia Fagundes. Effect of strength training with restriction blood flow on reactivity of the abdominal aorta in Wistar rats. 2021. 86 p. Thesis (Doctr’s in Rehabilitation and Functional Performance) – Faculty of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, 2021. Strength training (ST) with blood flow restriction (BFR) promotes increases in hypertrophy and strength, sometimes similar to traditional ST. However, the effects of arterial BFR on muscle adaptations are not well up-to-date. However, the consequences of high-intensity ST (above 70% of 1 maximum voluntary contraction MVC) can bring complications (exaggerated cardiovascular responses in vascular function, structural remodeling and can also lead to orthopedic complications, for example) in certain prev, such as the elderly or people with special health conditions, making it unfeasible. Alternatively, studies indicate that strength training with blood flow restriction with low load intensity (20-50% of 1 MVC) can produce cheerful, positive adaptations to the ST with intensity or equal to 70% 1 MVC. However, few studies have investigated its effects on vascular function. Furthermore, there is a lot of divergence in the methodology applied in studies with strength training with blood flow restriction in humans, and, consequently, we found studies with different means. Thus, despite the evidence suggesting that strength training with restricted blood flow (STBFR) is safe, further investigation is still needed, especially vascular health. Due to these difficulties, we opted for a training protocol with arterial BFR in an animal model. Therefore, two studies were proposed to meet the following objectives; to evaluate whether STBRF can improve muscle adaptations, performance, and safety of performing this method in Wistar rats (manuscript 1) and to evaluate the effects of STBFR on the vascular function of these animals (manuscript 2). The experimental protocol included the use of 8-week-old Wistar Hannover rats, divided into four groups: sham sedentary (S/S), sedentary with arterial BFR (S/BFR), sham trained (T/S) and trained with arterial BFR (T/BFR), and the groups with BFR underwent arteriovenous surgery to restrict the blood flow of the femoral artery. The training protocol consisted of four weeks of ST consisting of 6 sets of 10 stair climbs with 50% of 1 MVC. At the beginning and the end of the protocol, data on body weight, epididymal fat, maximum weight carried, handgrip strength, muscle hypertrophy index, systolic blood pressure, superoxide dismutase enzymatic activity, nitrite/nitrate concentration, and factor, alpha tumor necrosis (manuscript 1). Concentration-response curves in the abdominal aorta to acetylcholine (ACh: 10nM 100μM) and phenylephrine (PHE: 1nM 30μM), nitric oxide (NO) production and reactive oxygen species (ROS), vascular remodeling (metalloproteinase matrix-2) and gelatinolytic activity (zymography) (manuscript 2). Normality and homogeneity were verified by the Shapiro-Wilk and Levene tests, respectively. The statistic used was the two-way ANOVA, followed by a Bonferroni post-test. P-values < 0.05 using GraphPad Prism program. The T/BFR group showed increased strength and muscle hypertrophy. On the other hand, T/S was effective in increasing strength but with no effect on hypertrophy. Furthermore, no significant cardiac and metabolic alterations were found (manuscript 1). In this context, it is understood that the training protocol was effective, as it increased the strength of the T/S and T/BFR animals in the maximum loaded weight tests. The animals in the S/S group reduced dissipation in ACh (Emax 22%) compared to the S/BFR, and strength training prevented reducing relaxation in the T/BFR group. For the T/S group, no improvement in relaxation was found when compared to the sedentary pairs. The maximal response to the alpha-agonist agent was increased by 80% in S/BFR animals. Physical training didn’t change the maximal response. Still, animals in the T/S and T/BFR groups reduced by 4 to 4.5 times, respectively, insensitivity to PHE, and in the S/BFR group, this reduction was six times. The T/S group showed an increase in NO production, and both T/S and T/BFR decreased in situ ROS production (62% and 40%, respectively). Furthermore, both groups trained reduced the gelatinolytic activity of MMP-2 in the aorta (manuscript 2). In conclusion, T/BFR can improve muscle adaptations and performance in rats without causing cardiovascular and metabolic damage. These results are unprecedented, promising, and improvement that, in addition to strength training, the BFR should be considered an alternative clinical intervention for both physical performance to improve endothelial health.