Effects of cardioselective and nonselective beta-adrenergic blockade on the performance of highly trained runners.

Twenty-five highly trained runners with a maximal oxygen uptake (VO2 max) of 64.7 +/- 4.3 ml . kg-1. min-1 were administered clinically equivalent doses of a nonselective (propranolol) and a cardioselective (atenolol) beta-blocking agent as well as a placebo. The subjects performed a horizontal treadmill test on the eighth day and a 10-km track race on the tenth day of each treatment. Beta blockade decreased submaximal heart rate and propranolol caused the largest decrease. Beta blockade caused a decrease in maximal heart rate, VO2 max, maximal ventilation, maximal respiratory exchange ratio and treadmill time. Propranolol caused a greater decrease than atenolol in each of these values. The 10-km race times were significantly slower during beta blockade, and propranolol race times were significantly slower than atenolol race times. It is concluded that the performance of highly trained distance runners is significantly altered by beta-adrenergic blockade and that nonselective agents reduce performance to a greater extent than cardioselective agents.