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Effects of Verapamil and Atenolol on Exercise Tolerance in 5,000 m Cross-Country Running: A Double-Blind Cross-Over Study in Normal Humans

Summary: The effects on exercise tolerance of 7-day treatment with a calcium channel blocker, verapamil 160 mg twice daily (b.i.d.), and a β1-selective blocker, atenolol 50 mg b.i.d., were compared in 10 healthy and physically active young subjects in 5,000-m cross-country running at high intensity. The study was a double-blind cross-over trial. Comparison was made with a single-blind placebo as well. Performance time was measured every 1,000 m in seven 5,000-m runs, in which subjects were instructed to keep to a constant fatigue perception (Borg scale rating). Both drugs significantly (p = 0.001) increased the performance time over the first 1,000 m as compared with placebo. However, running time after 1,000, 2,000, and 3,000 m was prolonged significantly less (p < 0.05) by verapamil than by atenolol. For the entire 5,000-m run, atenolol caused a significant increase (p = 0.001) in mean running time by 1 min 34 s (i.e., 7.5%; 95% confidence interval 48 s to 2 min 21 s) as compared with placebo, whereas verapamil caused no significant change (+46 s).