Effects of diltiazem and atenolol on exercise performance in man

The effects of diltiazem and atenolol on exercise performance were studied in 9 healthy and physically fit volunteers according to a double-blind cross-over design. All subjects performed, with an interval of 1 week, 3 exercise tests on a treadmill with stepwise increase of the workload until exhaustion. Two hours prior to each exercise test they received in a randomised order placebo, diltiazem 120 mg or atenolol 100 mg. Running time and VO2peak were not influenced by diltiazem, while running time was significantly reduced (-10%) after atenolol. The reduction of VO2peak (-9%) after atenolol did not reach statistical significance. Both diltiazem and atenolol significantly decreased heart rate at peak effort but the decrease was much more pronounced after atenolol (-52 b.min-1) than after diltiazem (-6 b.min-1). At submaximal level VO2 was not influenced by diltiazem, but significantly lowered (-6%) after atenolol. Submaximal heart rate was decreased and plasma lactate concentration was increased by both diltiazem and atenolol, but the effect of atenolol was more pronounced. The study shows that maximal work performance of young healthy subjects is not affected by diltiazem 120 mg, in contrast to atenolol 100 mg which decreases maximal work performance in the same subjects.