Efficacy of antihypertensive therapy at rest and during exercise

The effects of different classes of antihypertensive medication on blood pressure response to exercise were investigated in 15 patients with hypertension. The agents evaluated included a diuretic (hydrochlorothiazide), a β-adrenergic blocker (propranolol), a central adrenergic blocker (clonidine), and a vasodilator (hydralazine), which were administered in a randomized trial. Blood pressure was evaluated when the patient was not receiving medications and when the patient received the four drugs at rest and during treadmill exercise, and these results were compared with those obtained in patients who were nonhypertensive and were not receiving any medications. Systolic and diastolic blood pressures at rest, during submaximal exercise, at maximal exercise, and after exercise were significantly lower in the nonhypertensive group than in the untreated hypertensive patients (P < .01). In the hypertensive group, mean functional capacity determined by exercise evaluation was similar in the absence and presence of the four antihypertensive drugs. Blood pressure comparisons were made of the individual antihypertensive agents versus control by repeated measures Analysis of Variance (ANOVA) (significance: P < .01). Hydrochlorothiazide and propranolol reduced systolic and diastolic blood pressures before exercise, at most levels during exercise, and after exercise. Systolic and diastolic blood pressures after clonidine treatment were reduced significantly at all points except maximal workload. Hydralazine did not affect the resting systolic or diastolic blood pressure significantly but did reduce systolic pressure at 35% maximal workload and 2 minutes after exercise and diastolic pressure at 55% maximal workload, at maximal workload, and 2 minutes after exercise. Comparison of hydrochlorothiazide and propranolol demonstrated a similar reduction of resting blood pressure; however, the systolic blood pressure during propranolol treatment was significantly lower at all levels of exercise and after exercise. These observations demonstrate different exercise hemodynamic responses to four classes of antihypertensive medication that may have implications for therapeutic application of these agents.