title: Impact of aerobic fitness on cerebral blood flow and cerebral vascular responsiveness to CO2in young and older men.
abstract: We sought to test the hypothesis that brain blood flow and cerebral vascular responsiveness to carbon dioxide (CVRCO2) are greater in aerobically trained young and old individuals compared to their untrained counterparts. In 11 young trained {[23 (20-26) years] [mean (95% confidence interval)]}, 10 young untrained [25 (22-28) years], 8 older trained [65 (61-69) years], and 9 older untrained [67 (64-71) years] healthy individuals, Doppler ultrasound of the internal carotid (ICA) and vertebral (VA) artery blood flow were determined, along with middle cerebral artery mean flow velocity (MCA Vmean). Bilateral ICA blood flow was higher in trained individuals when compared to untrained (≈31%, P < 0.05), but was not influenced by age. VA blood flow was not affected by age or cardiorespiratory fitness. MCA Vmeanwas reduced with age [59.5 (55.0-64.1) cm/s young vs 43.6 (38.4-48.9) cm/s old, P < 0.05] with no significant effect of training observed. MCA CVRCO2were not significantly affected by either age or training status, while ICA CVRCO2tended to be elevated in the old trained group. These findings indicate that endurance training enhances bilateral ICA but not VA blood flow in both young and older individuals.
authors.affiliation: School of Sport, Exercise & Rehabilitation Sciences, College of Life & Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK.
authors.forename: I D
authors.initials: ID
authors.lastname: Braz
authors.affiliation: Zurich Center for Integrative Human Physiology (ZIHP), Zurich, Switzerland.|Institute of Physiology, University of Zurich, Zurich, Switzerland.
authors.forename: D
authors.initials: D
authors.lastname: Flück
authors.affiliation: University of Birmingham Centre for Cardiovascular Sciences, City Hospital, Birmingham, UK.
authors.forename: G Y H
authors.initials: GYH
authors.lastname: Lip
authors.affiliation: Zurich Center for Integrative Human Physiology (ZIHP), Zurich, Switzerland.|Institute of Physiology, University of Zurich, Zurich, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Lundby
authors.affiliation: School of Sport, Exercise & Rehabilitation Sciences, College of Life & Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, UK.
authors.forename: J P
authors.identifier: http://orcid.org/0000-0001-7851-9222
authors.initials: JP
authors.lastname: Fisher
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001794:Blood Pressure; D002245:Carbon Dioxide / Q000502:physiology*; D000072599:Cardiorespiratory Fitness; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005080:Exercise Test; D006339:Heart Rate; D006801:Humans; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000502:physiology; D064797:Physical Conditioning, Human; D010807:Physical Endurance / Q000502:physiology*; D057185:Sedentary Behavior; D014711:Vertebral Artery / Q000502:physiology; D055815:Young Adult
chemical_list: D002245:Carbon Dioxide
keywords: Aging; cardio-respiratory fitness; cerebrovascular circulation