title: Cardiovascular adaptations to 10 days of cycle exercise.
abstract: We hypothesized that 10 days of training would enhance cardiac output (CO) and stroke volume (SV) during peak exercise and increase the inotropic response to beta-adrenergic stimulation. Ten subjects [age 26 +/- 2 (SE) yr] trained on a cycle ergometer for 10 days. At peak exercise, training increased O2 uptake, CO, and SV (P < 0.001). Left ventricular (LV) size and function at rest were assessed with two-dimensional echocardiography before (baseline) and after atropine injection (1.0 mg) and during four graded doses of dobutamine. LV end-diastolic diameter increased with training (P < 0.02), whereas LV wall thickness was unchanged. LV contractile performance was assessed by relating fractional shortening (FS) to the estimated end-systolic wall stress (sigmaES). Training increased the slope of the FS-sigmaES relationship (P < 0.05), indicating enhanced systolic function. The increase in slope correlated with increases in CO (r = -0.71, P < 0.05) and SV (r = -0.70, P < 0.05). The increase in blood volume also correlated with increases in CO (r = 0.80, P < 0.01) and SV (r = 0.85, P < 0.004). These data show that 10 days of training enhance the inotropic response to beta-adrenergic stimulation, associated with increases in CO and SV during peak exercise.
authors.affiliation: Section of Applied Physiology, Department of Internal Medicine, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
authors.forename: C M
authors.initials: CM
authors.lastname: Mier
authors.forename: M J
authors.initials: MJ
authors.lastname: Turner
authors.forename: A A
authors.initials: AA
authors.lastname: Ehsani
authors.forename: R J
authors.initials: RJ
authors.lastname: Spina
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D001642:Bicycling; D002302:Cardiac Output / Q000187:drug effects / Q000502:physiology; D002395:Catecholamines / Q000097:blood; D015444:Exercise / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D009200:Myocardial Contraction / Q000502:physiology; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology; D010809:Physical Fitness / Q000502:physiology*; D010953:Plasma Volume / Q000187:drug effects / Q000502:physiology; D013318:Stroke Volume / Q000187:drug effects / Q000502:physiology; D016277:Ventricular Function, Left / Q000187:drug effects / Q000502:physiology
chemical_list: D000318:Adrenergic beta-Agonists; D002395:Catecholamines