Cardiac and skeletal muscle adaptations to training in systemic hypertension and effect of beta blockade (metoprolol or propranolol)

Cardiovascular and peripheral adaptations to an aerobic conditioning program were studied in 30 hypertensive adults taking either placebo, β1-selective β-adrenergic blocker (metoprolol) or β1-nonselective β-adrenergic blocker (propranolol). The placebo group increased aerobic capacity (VO2max) 24% (p < 0.002), largely explained by an increased peripheral arteriovenous (AV) oxygen difference with minimal changes in cardiac size and function. Resting blood pressure and total systemic resistance also decreased. The group taking a β-selective β blocker increased VO2max 8% (p < 0.05), reduced resting blood pressure but had no significant change of AV oxygen difference or cardiac size or function. The group taking the β1-nonselective β blocker propranolol had no increase inVO2max, no decrease in resting blood pressure and no cardiovascular or peripheral adaptations to the exercise program. Thus, β1-selective and β1-nonselective β blockers attenuate conditioning in hypertensive patients to differing degrees, in each case by blocking peripheral mechanisms of conditioning.