title: Vascular conductance and aerobic power in sedentary and active subjects and heart failure patients.
abstract: The relationship between peak aerobic power and a strain-gauge determination of local skeletal muscle vascular conductance 10-13 s after calf exercise to fatigue was examined in 21 middle-aged adults (age 38.1 +/- 2.5 yr): seven physically active men (A), seven sedentary men (S), and six men and one woman with compensated idiopathic heart failure (HF). The three subgroups were chosen as differing widely in peak O2 intake [48.2 +/- 1.2, 32.9 +/- 1.6, and 16.1 +/- 1.3 (SE) ml.kg-1 x min-1, respectively]. Calf vascular conductance showed a gradation with aerobic power: 64.8 +/- 3.8, 40.7 +/- 4.3, and 30.7 +/- 6.1 (SE) ml/min local flow per 10 liters of tissue per unit of blood pressure. There was a strong positive correlation between O2 intake and vascular conductance for the overall group (VO2 = 0.614 G + 3.5; r = 0.75, P < 0.001) and for the 14 normal subjects (VO2 = 0.377 G + 20.6; r = 0.74, P < 0.002). The mean conductance was smaller in HF (P < 0.001), with no significant slope in relation to O2 intake. There was no relationship between the resting cardiac ejection fraction [74.4 +/- 4.1% (SE) for A, 74.3 +/- 4.2% for S, and 25.8 +/- 5.2% for HF] and either peak aerobic power or calf vascular conductance. We conclude that peak aerobic power is strongly associated with local vascular conductance during peripherally limited exercise involving the calf muscles of one leg and that vascular conductance is particularly low in subjects with compensated idiopathic heart failure.
authors.affiliation: School of Physical and Health Education, University of Toronto, Ontario, Canada.
authors.forename: J L
authors.initials: JL
authors.lastname: Reading
authors.forename: J M
authors.initials: JM
authors.lastname: Goodman
authors.forename: M J
authors.initials: MJ
authors.lastname: Plyley
authors.forename: J S
authors.initials: JS
authors.lastname: Floras
authors.forename: P P
authors.initials: PP
authors.lastname: Liu
authors.forename: P R
authors.initials: PR
authors.lastname: McLaughlin
authors.forename: R J
authors.initials: RJ
authors.lastname: Shephard
mesh_terms: D000328:Adult; D000332:Aerobiosis; D001794:Blood Pressure / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology; D002303:Cardiac Output, Low / Q000503:physiopathology*; D005080:Exercise Test; D005221:Fatigue / Q000503:physiopathology; D005260:Female; D006801:Humans; D007773:Lactates / Q000097:blood; D019344:Lactic Acid; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000502:physiology*; D009132:Muscles / Q000098:blood supply / Q000000981:diagnostic imaging / Q000502:physiology; D010101:Oxygen Consumption / Q000502:physiology; D010477:Perfusion; D005082:Physical Exertion / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology*; D010991:Plethysmography; D011877:Radionuclide Imaging; D016277:Ventricular Function, Left / Q000502:physiology
chemical_list: D007773:Lactates; D019344:Lactic Acid