Does Beta-Blocker Therapy Reduce the Cardiovascular Benefit of Aerobic Exercise in Patients with Arterial Hypertension?
Regular aerobic exercise is generally recommended for patients suffering from arterial hypertension to reduce blood pressure values, improve physical fitness, and other parameters. The intensity of exercise is most often derived from the target heart rate, which is pharmacologically influenced in patients on beta-blockers. The question, therefore, is whether aerobic exercise brings the same cardiovascular benefit to this group of patients as it does to those not taking beta-blockers.
Introduction
Aerobic physical exercise is recommended to patients with arterial hypertension as a fundamental non-pharmacological intervention leading to a reduction in blood pressure values, improvement in endothelial functions, and reduction in vascular resistance. Professional societies recommend regular physical activity of moderate intensity, such as walking, jogging, or swimming for 30–45 minutes 3–4 times a week. The training intensity should range between 40–60% of maximum oxygen consumption. Higher values do not represent a benefit and can contribute to an increase in blood pressure values in patients with arterial hypertension.
The intensity of exercise is usually monitored through heart rate, with optimal values potentially determined by lactate threshold or ventilatory parameters. However, these methods are complex and unsuitable for general use, so optimal heart rate is most often empirically determined.
According to professional societies, it ranges between 55–85% of maximum heart rate. A specific group, however, comprises hypertensive patients on beta-blocker (BB) therapy, such as the widely used bisoprolol. In patients on BB, heart rate is lower both at rest and during exertion, and target heart rate values during exercise may differ from general recommendations. The question also arises as to whether regular exercise benefits patients on BB.
Methodology and Study Progress
The study included 52 patients, 23 of whom were on beta-blocker therapy (e.g., bisoprolol), while 29 were without this therapy. Inclusion criteria included age ≥ 60 years, systolic blood pressure ≥ 140 mmHg measured by 24-hour ambulatory monitoring, and/or the use of antihypertensive therapy.
Patients were randomized to either a sedentary lifestyle or a treadmill exercise program for 12 weeks. The training program consisted of treadmill walking 3 times a week, with training intensity corresponding to a blood lactate level of 2.0 ± 0.5 mmol/L. Lactate levels were checked every fifth training day, and if levels dropped below 1.8 mmol/L or rose above 2.2 mmol/L, the target heart rate was adjusted to achieve the target lactate level in the blood.
Results
A significant reduction in systolic and diastolic blood pressure measured by 24-hour ambulatory monitoring, a reduction in exercise blood pressure (100 W), and increased endothelium-dependent vasodilation was observed in both groups of patients undergoing regular physical activity with or without beta-blocker therapy (p < 0.05 for both groups). The reduction in blood pressure was not statistically significant between the BB and non-BB groups (average reduction in systolic blood pressure 10.6 ± 10.5 vs. 10.6 ± 8.8 mmHg, average reduction in diastolic blood pressure 5.7 ± 8.6 vs. 5.8 ± 4.0 mmHg). The reduction in blood pressure could not be attributed to a reduction in BMI as there were no significant changes in this parameter during the observation period.
Patients on beta-blocker therapy exhibited a significantly lower average heart rate both during exercise and at rest compared to other patients (during exercise 97.2 ± 7.7 vs. 118.3 ± 7.5/min; p < 0.001; at rest 68.2 ± 7.5 vs. 84.9 ± 9.4/min; p < 0.001). The average lactate level between the groups was not significantly different (1.9 ± 0.4 vs. 2.1 ± 0.5 mmol/L; p > 0.05).
Conclusion
The study results indicate that aerobic exercise, with adjusted target heart rate according to blood lactate level, provided similar cardiovascular benefits in hypertensive patients on beta-blocker therapy as it did in those without this therapy. An 18% lower target heart rate was observed in patients on BB compared to others. According to the authors, further research is needed to clarify target heart rate for patients on BB.
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Source: Westhoff T. H., Franke N., Schmidt S. et al. Beta-blockers do not impair the cardiovascular benefits of endurance training in hypertensives. J Hum Hypertens 2007; 21 (6): 486–493, doi: 10.1038/sj.jhh.1002173.
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