We investigated the influence of angiotensin-converting enzyme inhibitor (ACEi) treatment and physical exercise on arterial pressure (AP) and heart rate variability (HRV) in volunteer patients with hypertension. A total of 54 sedentary volunteers were divided into three groups: normotensive (NT Group), hypertensive (HT Group) and HT volunteers treated with ACEi (ACEi Group). All volunteers underwent an aerobic physical-training protocol for 15 weeks. HRV was investigated using a spectral analysis of a time series of R-R interval (RRi) that was obtained in a supine position and during a tilt test. Physical training promoted a significant reduction in the mean arterial pressure of the HT group (113 ± 3 vs. 106 ± 1 mm Hg) and the ACEi group (104 ± 2 vs. Keywords: aerobic physical training; angiotensin; heart rate variability INTRODUCTION Hypertension is highly prevalent in the adult population and represents one of the leading causes of morbidity and mortality worldwide. 1,2 This condition is directly related to the development of cardiovascular diseases, encephalic vascular accident and renal insufficiency. 3 The risk factors for hypertension are associated with many other factors, including lifestyle. 4 The excessive ingestion of salt and alcohol, obesity, smoking and sedentariness represent the main behavioral factors that contribute to the occurrence and development of hypertension. 5 The treatment of hypertension consists mainly of a pharmacological approach, and the angiotensin-converting enzyme inhibitors (ACEis) are an important class of medications. 6 ACEis reduce arterial pressure (AP) by decreasing the peripheral vascular resistance, and they reduce cardiac hypertrophy and the proliferation of vascular smooth muscle cells. 7-9 Additionally, ACEis have an important role in cardiac autonomic control. Some studies have shown that ACEi treatment of hypertension in experimental animals and humans improves baroreflex

Our results showed that nitric oxide synthesis blockade impaired the cardiovascular autonomic adaptations induced by previous aerobic physical training in rats that might be, at least in part, ascribed to a decreased baroreflex sensitivity.

We investigated the effects of selective loads of periodization model (SLPM) on autonomic modulation of heart rate variability (HRV) and endogenous stress markers before and after a competition period in volleyball players (N=32). The experimental protocol for the evaluation of HRV consisted of using spectral analysis of time series composed of the R-R intervals derived from electrocardiogram obtained in the supine position and during the tilt test. Stress marker levels were determined by quantifying the plasma concentration of endogenous catecholamines, cortisol and free testosterone. The results showed no changes between the levels of HRV before and after a competition period. In contrast, the quantification of the plasma concentration of endogenous stress markers revealed reductions in the levels of total catecholamines, noradrenaline and cortisol. These changes were accompanied by increases in the concentration of free testosterone and in the testosterone/cortisol ratio. In conclusion, our results demonstrate that the SLPM did not change the cardiac autonomic modulation of HRV, but promoted beneficial adaptations in athletes, including positive changes in the plasma concentration of the endogenous stress markers. The absence of changes in HRV indicates that there is no direct relationship between cardiac autonomic modulation and endogenous stress markers in the present study.

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Aos meus pais, família, amigos queridos, ao meu namorado, que sempre me apoiaram nas minhas escolhas. Obrigada por acreditar.Ao meu orientador, Dr. Ubiratan de Paula Santos, muito obrigada pela oportunidade, pela confiança, pela dedicação e pela parceria.Aos membros da banca, obrigada pela presença e pela oportunidade de aprendizado.