Effects of cardioselective and nonselective β‐blockade on dynamic exercise performance in mildly hypertensive men

In a double‐blind, crossover study mildly hypertensive men were given placebo, atenolol (50 and 100 mg 3 times a day), and propranolol (40 and 80 mg 3 times a day), each for 1 wk. Changes in blood pressure, heart rate, arterial blood gases, electrolytes, glucose, lactate, and plasma renin activity (PRA) during bicycle exercise with step‐wise increases in work load until exhaustion were assessed with and without β‐blockade. β‐Blockade did not affect maximal work load. Blood pressure and heart rate showed the expected responses to exercise and β‐blockade. The arterial values for pH, lactate, and glucose were not affected by β‐blockade either at rest or at exhaustion. The rise in plasma potassium due to exercise was higher on the β‐blockers than on placebo and the rise in PRA was suppressed in a dose‐dependent manner to the same degree by both β‐blockers. In a second double‐blind study in mildly hypertensive men, the effects of placebo and atenolol (100 mg twice daily) for 1 wk were assessed on exercise performance of a trained and an untrained group. In this study, β‐blockers again did not affect the maximal work load reached. The responses of systolic and diastolic blood pressure did not differ between the 2 groups, whereas the heart rate of the trained group was lower at rest and during the initial part of the exercise on both placebo and atenolol. These results indicate that the circulatory and metabolic changes induced by effective β 1 , and β 1 and 2 blockade for 1 wk do not limit maximal physical performance during short‐term dynamic exercise. Clinical Pharmacology and Therapeutics (1980) 28, 12–21; doi: 10.1038/clpt.1980.124