title: Cerebrovascular responses to submaximal exercise in women with COPD.
abstract: BACKGROUND
  COPD patients have decreased physical fitness, and have an increased risk of vascular disease. In the general population, fitness is positively associated with resting cerebral blood flow velocity, however, little is known about the cerebrovascular response during exercise particularly in COPD patients. We hypothesized that COPD patients would have lower cerebral blood flow during exercise secondary to decreased physical fitness and underlying vascular disease.
  
  
  METHODS
  Cardiopulmonary exercise testing was conducted in 11 women with GOLD stage I-II COPD, and 11 healthy controls to assess fitness. Cerebro- and cardio-vascular responses were compared between groups during two steady-state exercise tests (50% peak O2 consumption and 30 W). The main outcome variable was peak middle cerebral artery blood flow velocity (VP) during exercise using transcranial Doppler ultrasonography.
  
  
  RESULTS
  Physical fitness was decreased in COPD patients. VP was comparable between COPD and controls (25 ± 22% versus 15 ± 13%, respectively; P > 0.05) when exercising at the same relative intensity, despite patients having higher blood pressure and greater arterial desaturation. However, VP was elevated in COPD (31 ± 26% versus 13 ± 10%; P ≤ 0.05) when exercising at the same workload as controls.
  
  
  CONCLUSIONS
  Our results are contradictory to our a-priori hypothesis, suggesting that during matched intensity exercise, cerebral blood flow velocity is similar between COPD and controls. However, exercise at a modestly greater workload imposes a large physical demand to COPD patients, resulting in increased CBF compared to controls. Normal activities of daily living may therefore impose a large cerebrovascular demand in COPD patients, consequently reducing their cerebrovascular reserve capacity.
authors.forename: Sara E
authors.initials: SE
authors.lastname: Hartmann
authors.forename: Richard
authors.initials: R
authors.lastname: Leigh
authors.affiliation: Department of Physiology and Pharmacology, Faculty of Medicine, University of Calgary, Calgary, AB, Canada. poulin@ucalgary.ca.
authors.forename: Marc J
authors.initials: MJ
authors.lastname: Poulin
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D002560:Cerebrovascular Circulation / Q000502:physiology*; D005080:Exercise Test / Q000379:methods*; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006801:Humans; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D005082:Physical Exertion; D010809:Physical Fitness / Q000502:physiology*; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D012016:Reference Values; D012129:Respiratory Function Tests; D012720:Severity of Illness Index; D017585:Ultrasonography, Doppler, Transcranial