Changes in stroke volume with beta-blockade before and after 10 days of exercise training in men and women.
We sought to determine whether 10 days of training would be a sufficient stimulus for cardiac adaptations that would allow a greater compensatory stroke volume during beta-blockade. We also sought to determine whether men and women had a similar cardiac reserve capacity for increasing stroke volume with beta-blockade during submaximal exercise. Eight men (age 29 +/- 2 yr, mean +/- SE) and eight women (25 +/- 2 yr) cycled at 65% of peak O2 consumption (unblocked) under placebo-control and beta-blockade (100 mg atenolol) conditions performed on separate days. These tests were repeated at the same power output after training (10 consecutive days, 1 h of cycling per day). Before training, beta-blockade significantly (P < 0.05) decreased heart rate (HR) and cardiac output and increased stroke volume in both men and women. After training, the increase in stroke volume and decrease in HR with beta-blockade was significantly less while cardiac output was reduced more. There were no gender differences in the effects of beta-blockade on HR, stroke volume, or cardiac output. These data indicate that, during exercise with beta-blockade, exercise training for 10 days does not enhance the compensatory increase in stroke volume and that men and women have a similar cardiac reserve capacity for increasing stroke volume.
Mier
C M
CM
Department of Kinesiology and Health Education, University of Texas at Austin 78712, USA. CMIER@BU4090.barry.edu
Domenick
M A
MA
Wilmore
J H
JH
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000328:Adult; D001262:Atenolol / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects / Q000502:physiology; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000187:drug effects; D010809:Physical Fitness / Q000502:physiology*; D012727:Sex Characteristics; D013318:Stroke Volume / Q000187:drug effects* / Q000502:physiology*
D000319:Adrenergic beta-Antagonists; D001262:Atenolol