Exercise testing and training with beta-adrenergic blockade: role of the drug washout period in "unmasking" a training effect.
To determine whether or not a training effect can be achieved with beta-adrenergic blockade and whether there is a difference between selective and nonselective therapy, we recruited 40 healthy subjects (16 women, 24 men) to participate in a 9-week exercise training program. After a baseline exercise treadmill test, subjects were randomized to oral therapy groups of atenolol, 50 mg daily (AT 50), atenolol, 100 mg daily (AT 100), propranolol, 80 mg twice a day (Prop), or placebo. Repeat exercise tests were performed at week 1, week 8, and at week 9, with week 8 to 9 being a 1-week drug-free washout period. At week 8, maximal oxygen consumption (Max VO2), when compared with baseline levels, was increased slightly in AT 50 (4.2%) and Prop (2.4%), decreased in AT 100 (5.3%), and increased significantly in the placebo group (12.7%). After washout, Max VO2 increased significantly compared with baseline in AT 50, AT 100, and Prop (9.8%, 10.8%, and 9.8%, respectively). We conclude that there is no significant difference between selective and nonselective beta-blockade therapy in the development of a training effect. This effect, however, may not become apparent until the drug is withdrawn.
Sweeney
M E
ME
Department of Rehabilitation Medicine, Emory University School of Medicine, Atlanta, GA.
Fletcher
B J
BJ
Fletcher
G F
GF
D000319:Adrenergic beta-Antagonists / Q000493:pharmacokinetics / Q000494:pharmacology*; D000328:Adult; D001262:Atenolol / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D005080:Exercise Test; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects; D010806:Physical Education and Training; D011433:Propranolol / Q000494:pharmacology; D012119:Respiration / Q000187:drug effects; D013997:Time Factors
D000319:Adrenergic beta-Antagonists; D001262:Atenolol; D011433:Propranolol