title: Discrepancy between cardiac and physical functional reserves in stroke.
abstract: OBJECTIVE
  Understanding the physiological limitations to exercise after stroke will assist the development of targeted therapies to improve everyday function. This study defines (1) whether exercise capacity is limited by the cardiovascular system (oxygen supply) or skeletal muscles (oxygen utilization); and (2) cardiac function and pumping capability in people with stroke.
  
  
  METHODS
  Twenty-eight male participants with mild ischemic stroke (70 ± 6 years of age, 18 ± 20 months poststroke) and 25 male, age-matched healthy control subjects performed a graded cardiopulmonary exercise test with gas exchange and noninvasive hemodynamic measurements. Maximal oxygen extraction was calculated as the ratio between peak oxygen consumption and peak cardiac output. Cardiac function and pumping capability were assessed by peak exercise cardiac power output (expressed in watts) and cardiac output.
  
  
  RESULTS
  Peak oxygen consumption (18.4 ± 4.6 versus 26.8 ± 5.5 mL/kg/min, P<0.01) and arterial-venous O(2) difference (9.3 ± 2.5 versus 12.6 ± 1.9 mlO(2)/100 mL of blood, P<0.01) were both reduced in stroke participants compared with healthy control subjects. In contrast, peak exercise cardiac power output (4.79 ± 0.79 versus 4.51 ± 0.96 W, P=0.49), cardiac output (16.4 ± 3.1 versus 17.1±2.5 L/min, P=0.41), and the pressure-generating capacity of the heart (127±11 versus 125 ± 14 mm Hg, P=0.97) were similar between stroke participants and healthy control subjects.
  
  
  CONCLUSIONS
  The ability of skeletal muscles to extract oxygen is diminished after stroke. However, cardiac function and pumping capability are maintained. Appropriate therapies targeting muscle oxygen uptake such as exercise rehabilitation may improve exercise capacity after stroke.
authors.affiliation: Newcastle University, Newcastle upon Tyne, NE2 4HH, UK. d.jakovljevic@ncl.ac.uk
authors.forename: Djordje G
authors.initials: DG
authors.lastname: Jakovljevic
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Moore
authors.forename: Lip-Bun
authors.initials: LB
authors.lastname: Tan
authors.forename: Lynn
authors.initials: L
authors.lastname: Rochester
authors.forename: Gary A
authors.initials: GA
authors.lastname: Ford
authors.forename: Michael I
authors.initials: MI
authors.lastname: Trenell
mesh_terms: D000368:Aged; D002302:Cardiac Output / Q000502:physiology; D016022:Case-Control Studies; D015444:Exercise / Q000502:physiology*; D005081:Exercise Therapy; D006321:Heart / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D010101:Oxygen Consumption / Q000502:physiology; D020521:Stroke / Q000378:metabolism* / Q000503:physiopathology*; D000071939:Stroke Rehabilitation
chemical_list: D010100:Oxygen