title: Impaired leg vasodilation during dynamic exercise in healthy older women.
abstract: The purpose of the present study was to test the hypothesis that leg blood flow responses during leg cycle ergometry are reduced with age in healthy non-estrogen-replaced women. Thirteen younger (20-27 yr) and thirteen older (61-71 yr) normotensive, non-endurance-trained women performed both graded and constant-load bouts of leg cycling at the same absolute exercise intensities. Leg blood flow (femoral vein thermodilution), mean arterial pressure (MAP; radial artery), mean femoral venous pressure, cardiac output (acetylene rebreathing), and blood O2 contents were measured. Leg blood flow responses at light workloads (20-40 W) were similar in younger and older women. However, at moderate workloads (50-60 W), leg blood flow responses were significantly attenuated in older women. MAP was 20-25 mmHg higher (P < 0.01) in the older women across all work intensities, and calculated leg vascular conductance (leg blood flow/estimated leg perfusion pressure) was lower (P < 0.05). Exercise-induced increases in leg arteriovenous O2 difference and O2 extraction were identical between groups (P > 0.6). Leg O2 uptake was tightly correlated with leg blood flow across all workloads in both subject groups (r2 = 0.80). These results suggest the ability of healthy older women to undergo limb vasodilation in response to submaximal exercise is impaired and that the legs are a potentially important contributor to the augmented systemic vascular resistance seen during dynamic exercise in older women.
authors.affiliation: Noll Physiological Research Center, The Pennsylvania State University, University Park 16802-6900, USA. dnp3@psu.edu
authors.forename: David N
authors.initials: DN
authors.lastname: Proctor
authors.forename: Dennis W
authors.initials: DW
authors.lastname: Koch
authors.forename: Sean C
authors.initials: SC
authors.lastname: Newcomer
authors.forename: Khoi U
authors.initials: KU
authors.lastname: Le
authors.forename: Urs A
authors.initials: UA
authors.lastname: Leuenberger
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D005080:Exercise Test; D005260:Female; D006801:Humans; D007866:Leg / Q000098:blood supply* / Q000502:physiology; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*; D012039:Regional Blood Flow / Q000502:physiology; D014664:Vasodilation / Q000502:physiology*