title: Elevated aerobic fitness sustained throughout the adult lifespan is associated with improved cerebral hemodynamics.
abstract: OBJECTIVE
  Age-related impairments in cerebral blood flow and cerebrovascular reactivity to carbon dioxide (CVRCO2) are established risk factors for stroke that respond favorably to aerobic training. The present study examined to what extent cerebral hemodynamics are improved when training is sustained throughout the adult lifespan.
  
  
  METHODS
  Eighty-one healthy males were prospectively assigned to 1 of 4 groups based on their age (young, ≤30 years versus old, ≥60 years) and lifetime physical activity levels (trained, ≥150 minutes recreational aerobic activity/week versus sedentary, no activity). Middle cerebral artery blood velocity (MCAv, transcranial Doppler ultrasound), mean arterial pressure (MAP, finger photoplethysmography), and end-tidal partial pressure of carbon dioxide (PETCO2, capnography) were recorded during normocapnia and 3 mins of iso-oxic hypercapnea (5% CO2). Cerebrovascular resistance/conductance indices (CVRi/CVCi) were calculated as MAP/MCAv and MCAv/MAP, respectively, and CVRCO2 as the percentage increase in MCAv from baseline per millimeter of mercury (mm Hg) increase in PETCO2. Maximal oxygen consumption ( O2MAX, online respiratory gas analysis) was determined during cycling ergometry.
  
  
  RESULTS
  By design, older participants were active for longer (49±5 versus 6±4 years, P<0.05). Physical activity attenuated the age-related declines in O2MAX, MCAv, CVCi, and CVRCO2 and increase in CVRi (P<0.05 versus sedentary). Linear relationships were observed between O2MAX and both MCAv and CVRCO2 (r=0.58-0.77, P<0.05).
  
  
  CONCLUSIONS
  These findings highlight the importance of maintaining aerobic fitness throughout the lifespan given its capacity to improve cerebral hemodynamics in later-life.
authors: From the Neurovascular Research Laboratory, University of South Wales, UK (D.M.B., C.J.M., J.V.B., D.H., K.J.N.); the Department of Biomedical Engineering, Toyo University, Kawagoe-Shi, Saitama, Japan (S.O.); and the School of Health and Exercise Sciences, University of British Columbia Okanagan, Kelowna, Canada (P.N.A.).
authors: Damian M
authors: DM
authors: Bailey
authors: Christopher J
authors: CJ
authors: Marley
authors: Julien V
authors: JV
authors: Brugniaux
authors: Danielle
authors: D
authors: Hodson
authors: Karl J
authors: KJ
authors: New
authors: Shigehiko
authors: S
authors: Ogoh
authors: Philip N
authors: PN
authors: Ainslie
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D015444:Exercise; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D020768:Middle Cerebral Artery / Q000502:physiology; D010101:Oxygen Consumption; D010809:Physical Fitness; D011446:Prospective Studies; D012307:Risk Factors
keywords: aerobic exercise; aging; cerebrovascular circulation; perfusion; stroke