title: Reduced exercise arteriovenous O2 difference in Type 2 diabetes.
abstract: Maximal O(2) consumption (Vo(2 max)) is lower in individuals with Type 2 diabetes than in sedentary nondiabetic individuals. This study aimed to determine whether the lower Vo(2 max) in diabetic patients was due to a reduction in maximal cardiac output (Q(max)) and/or peripheral O(2) extraction. After 11 Type 2 diabetic patients and 12 nondiabetic subjects, matched for age and body composition, who had not exercised for 2 yr, performed a bicycle ergometer exercise test to determine Vo(2 max), submaximal cardiac output, Q(max), and arterial-mixed venous O(2) (a-v O(2)) difference were assessed. Maximal workload, Vo(2 max), and maximal a-v O(2) difference were lower in Type 2 diabetic patients (P < 0.05). Q(max) was low in both groups but not significantly different: 11.2 and 10.0 l/min for controls and diabetic patients, respectively (P > 0.05). Submaximal O(2) uptake and heart rate were lower at several workloads in diabetic patients; respiratory exchange ratio was similar between groups at all workloads. Vo(2 max) was linearly correlated with a-v O(2) difference, but not Q(max) in diabetic patients. These data suggest that a reduction in maximal a-v O(2) difference contributes to a decreased Vo(2 max) in Type 2 diabetic patients.
authors.affiliation: Departments of Sport and Exercise Science and Cardiovascular Research, School of Medicine, University of Auckland, Auckland, New Zealand. j.baldi@auckland.ac.nz
authors.forename: James C
authors.initials: JC
authors.lastname: Baldi
authors.forename: James L
authors.initials: JL
authors.lastname: Aoina
authors.forename: Helen C
authors.initials: HC
authors.lastname: Oxenham
authors.forename: Warwick
authors.initials: W
authors.lastname: Bagg
authors.forename: Robert N
authors.initials: RN
authors.lastname: Doughty
mesh_terms: D000328:Adult; D015308:Anaerobic Threshold / Q000502:physiology; D002245:Carbon Dioxide; D002302:Cardiac Output / Q000502:physiology; D003924:Diabetes Mellitus, Type 2 / Q000097:blood*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption / Q000502:physiology; D011659:Pulmonary Gas Exchange / Q000502:physiology
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen