Betabloqueio com atenolol não reduz potência aeróbia nem muda limiares ventilatórios em hipertensos sedentários / Atenolol beta-block does not decrease aerobic power or alter ventilatory thresholds in sedentary hypertensive subjects

INTRODUÇÃO: O exercício aeróbio é recomendado para o tratamento da hipertensão. Sua intensidade pode ser prescrita com base na porcentagem da frequência cardíaca máxima (%FCmáx) ou no consumo pico de oxigênio (%VO2pico) em que os limiares ventilatórios (LV) são alcançados. Entretanto, alguns hipertensos que iniciam o treinamento podem estar tomando betabloqueadores, o que pode influenciar esses parâmetros. OBJETIVO: verificar os efeitos do atenolol sobre os LV de hipertensos sedentários. MÉTODOS: Nove voluntários realizaram dois testes ergoespirométricos máximos após quatro semanas de tratamento com atenolol (25 mg administrado por via oral duas vezes por dia) e com placebo, administrados em ordem fixa e de forma cega. Durante os testes, a frequência cardíaca (FC), a pressão arterial (PA) e o VO2 no repouso, limiar anaeróbio (LA), ponto de compensação respiratória (PCR) e pico do esforço foram analisados. RESULTADOS: O VO2 aumentou progressivamente no exercício e seus valores foram semelhantes nos dois tratamentos. A PA sistólica e a FC também aumentaram no exercício, mas seus valores absolutos foram significativamente menores com o atenolol. Porém, o aumento da PA sistólica e da FC no exercício foi semelhante com os dois tratamentos. Assim, o percentual da FCmáx e o percentual do VO2pico em que LA e PCR foram alcançados não diferiram entre o placebo e o atenolol. CONCLUSÃO: O atenolol na dosagem de 50 mg/dia não afetou o percentual do VO2pico e da FCmáx em que os LV são atingidos, o que confirma que a prescrição de intensidade de treinamento com base nessas porcentagens pode ser mantida em hipertensos que recebem betabloqueadores.

INTRODUCTION: Aerobic exercise is recommended for the treatment of hypertension. Its intensity can be prescribed based on the percentage of maximum heart rate (% MHR) or peak oxygen consumption (VO2peak%) in which the ventilatory thresholds (VT) are achieved. However, some hypertensive patients who begin aerobic training may be receiving beta-blockers, which can influence these parameters. OBJECTIVE: To investigate the effects of atenolol on VT of sedentary hypertensive patients. METHODS: Nine volunteers performed two cardiopulmonary exercise tests until exhaustion after 4 weeks of treatment with atenolol (25 mg orally twice daily) and with placebo, administered in a fixed order and in a blinded manner. During the tests, heart rate (HR), blood pressure (BP), VO2 at rest, anaerobic threshold (AT), respiratory compensation point (RCP) and peak effort were analyzed. RESULTS: VO2 increased progressively throughout the exercise and the values were similar for both treatments. Systolic blood pressure and heart rate also increased progressively during the exercise, but their absolute values were significantly lower with atenolol. However, the increase in systolic BP and HR during exercise was similar in both treatments. Thus, the % of MHR and %VO2peak at which LA and PCR were achieved were not different between placebo and atenolol. CONCLUSION: Atenolol, at a dosage of 50mg/day, did not affect the % of VO2peak and % of MHR corresponding to the VTs, which confirms that prescription of training intensity based on these percentages is adequate to hypertensive patients receiving beta-blockers.

Acute and chronic effects of aerobic and resistance exercise on ambulatory blood pressure

Hypertension is a ubiquitous and serious disease. Regular exercise has been recommended as a strategy for the prevention and treatment of hypertension because of its effects in reducing clinical blood pressure; however, ambulatory blood pressure is a better predictor of target-organ damage than clinical blood pressure, and therefore studying the effects of exercise on ambulatory blood pressure is important as well. Moreover, different kinds of exercise might produce distinct effects that might differ between normotensive and hypertensive subjects. The aim of this study was to review the current literature on the acute and chronic effects of aerobic and resistance exercise on ambulatory blood pressure in normotensive and hypertensive subjects. It has been conclusively shown that a single episode of aerobic exercise reduces ambulatory blood pressure in hypertensive patients. Similarly, regular aerobic training also decreases ambulatory blood pressure in hypertensive individuals. In contrast, data on the effects of resistance exercise is both scarce and controversial. Nevertheless, studies suggest that resistance exercise might acutely decrease ambulatory blood pressure after exercise, and that this effect seems to be greater after low-intensity exercise and in patients receiving anti-hypertensive drugs. On the other hand, only two studies investigating resistance training in hypertensive patients have been conducted, and neither has demonstrated any hypotensive effect. Thus, based on current knowledge, aerobic training should be recommended to decrease ambulatory blood pressure in hypertensive individuals, while resistance exercise could be prescribed as a complementary strategy.

Intra-arterial blood pressure response in hypertensive subjects during low- and high-intensity resistance exercise

OBJECTIVE: The aim of this study was to describe blood pressure responses during resistance exercise in hypertensive subjects and to determine whether an exercise protocol alters these responses. INTRODUCTION: Resistance exercise has been recommended as a complement for aerobic exercise for hypertensive patients. However, blood pressure changes during this kind of exercise have been poorly investigated in hypertensives, despite multiple studies of normotensives demonstrating significant increases in blood pressure. METHODS: Ten hypertensive and ten normotensive subjects performed, in random order, two different exercise protocols, composed by three sets of the knee extension exercise conducted to exhaustion: 40 percent of the 1-repetition maximum (1RM) with a 45-s rest between sets, and 80 percent of 1RM with a 90-s rest between sets. Radial intra-arterial blood pressure was measured before and throughout each protocol. RESULTS: Compared with normotensives, hypertensives displayed greater increases in systolic BP during exercise at 80 percent (+80±3 vs. +62±2 mmHg, P<0.05) and at 40 percent of 1RM (+75±3 vs. +67±3 mmHg, P<0.05). In both exercise protocols, systolic blood pressure returned to baseline during the rest periods between sets in the normotensives; however, in the hypertensives, BP remained slightly elevated at 40 percent of 1RM. During rest periods, diastolic blood pressure returned to baseline in hypertensives and dropped below baseline in normotensives. CONCLUSION: Resistance exercise increased systolic blood pressure considerably more in hypertensives than in normotensives, and this increase was greater when lower-intensity exercise was performed to the point of exhaustion.