Effect of age on the exercise response in normal postmenopausal women during estrogen replacement therapy

Postmenopausal estrogen replacement therapy (ERT) has been associated with a reduced risk of coronary artery disease (CAD). Whether this apparent card ioprotective effect is mediated by a:cardiovascular benefit during exercise , however, has not been clearly defined. To evaluate rest and exercise vari ables with and without ERT, a randomized crossover trial was conducted in 2 3 postmenopausal women, ranging in age from 44 to 75 years, mean age 57 +/- 8 years. The rest and exercise variables were compared on ERT and during a drug-free period. The baseline measure was compared to the effects after 4 weeks of ERT and after 4 drug-free weeks. Echocardiographic treadmill exer cise variables of heart rate (HR), blood pressure, rate-pressure product (R PP), and cardiac dimensions were determined at baseline and at the end of e ach treatment period. In response to ERT, there was a decrease in low-densi ty lipoprotein (LDL) cholesterol (drug-free: 142 +/- 40 mg/dl, ERT: 124 +/- 34 mg/dl) and an increase in high-density lipoprotein (HDL) cholesterol (d rug-free: 52 +/- 14 mg/dl, ERT: 62 +/- 15 mg/dl, both p < 0.01). At rest, t he study population had no overall significant change in HR, blood pressure , RPP, or left ventricular end-systolic and end-diastolic diameters when ER T was compared to the drug-free period. However, subjects with the fastest baseline resting HR had the greatest decrease in HR with ERT relative to th e drug-free period (p < 0.05). During exercise, ERT effected no change in p eak HR, blood pressure, or RPP, although end-systolic diameter decreased sl ightly (p < 0.05). With ERT, subject age correlated negatively with systoli c blood pressure (p < 0.05) and RPP (p < 0.01); both blood pressure and RPP decreased in older subjects. In conclusion, ERT has differential effects d ependent on baseline HR and age.