Hypertension, exercise, and beta-adrenergic blockade

Abstract

Study objective: To determine whether beta-adrenergic blocking agents affect exercise tolerance, exercise conditioning response, and blood pressure response to conditioning in hypertensive patients.

Design: Randomized, double-blinded, placebo-controlled trial with a 10-week exercise period.

Setting: Outpatient, monitored exercise program at a community-based, university-sponsored cardiac rehabilitation facility.

Patients: Thirty adults with mean resting blood pressure of 145 mm Hg or greater (systolic), 95 mm Hg or greater (diastolic), or a combined systolic and diastolic pressure of 140/90 mm Hg or greater. Mean systolic pressure of 170 mm Hg or more or mean diastolic pressure of 105 mm Hg or more was exclusionary. Mean blood pressure was 145/95 mm Hg; mean age was 46.5 years.

Intervention: The beta-1-nonselective blocker was propranolol, 80 mg twice daily. The beta-1-selective blocker was metoprolol, 100 mg twice daily, compared with placebo. All patients did exercise conditioning consisting of 40 sessions of aerobic exercise with heart rate monitoring.

Measurements and main results: Resting systolic blood pressure measured without drug therapy was lowered markedly after exercise conditioning on placebo (146 to 135 mm Hg) and on metoprolol (144 to 133 mm Hg) (P less than 0.05), but not on propranolol (no change). Acutely, propranolol decreased both maximal oxygen consumption (VO2max) and exercise duration compared with metoprolol and placebo. Chronically, VO2max increased 24% (95% CI, 8 to 40) in response to training on placebo and 8% on metoprolol (95% CI, 3 to 14); it did not increase on propranolol (95% CI, -10 to 15).

Conclusions: If an exercise program is to be recommended as an adjunct to pharmacologic beta-blockade for hypertension, blood-pressure-lowering effects are preserved and exercise capacity is less affected with a beta-1-selective agent than with a beta-1-nonselective agent. Antihypertensive medications may be avoided altogether for selected patients who sustain an aerobic exercise program.