Effects of a week's beta-adrenoceptor blockade with atenolol and metoprolol CR/ZOK on the response to exercise in healthy women aged 50 to 70 years.

12 healthy women with a mean age of 60 years (range 50-70 years) were treated with 50 mg atenolol or 100 mg metoprolol CR/ZOK or placebo for 1 week in a double-blind, randomized, cross-over study. Laboratory measurements of the cardiovascular responses to exercise were made 2-4 hours after and again 24 hours after the last tablet. Blood pressure and heart rate at rest were reduced equally by the two beta-adrenoceptor antagonists. The reductions in blood pressure and heart rate during graded exercise and then during prolonged steady treadmill exercise 3-4 hours after the tablet were greater for atenolol than metoprolol CR/ZOK. The reductions in cardiac output showed a similar pattern. Lactate concentrations and ratings of perceived exertion tended to be highest on metoprolol CR/ZOK, but these differences were inconsistent. We conclude that despite the changes in the cardiovascular system in these 50-70 year-old women, exercise tolerance was not greatly affected by beta-adrenoceptor blockade.