title: Older type 2 diabetic males do not exhibit abnormal pulmonary oxygen uptake and muscle oxygen utilization dynamics during submaximal cycling exercise.
abstract: There are reports of abnormal pulmonary oxygen uptake (Vo(2)) and deoxygenated hemoglobin ([HHb]) kinetics in individuals with Type 2 diabetes (T2D) below 50 yr of age with disease durations of <5 yr. We examined the Vo(2) and muscle [HHb] kinetics in 12 older T2D patients with extended disease durations (age: 65 ± 5 years; disease duration 9.3 ± 3.8 years) and 12 healthy age-matched control participants (CON; age: 62 ± 6 years). Maximal oxygen uptake (Vo(2max)) was determined via a ramp incremental cycle test and Vo(2) and [HHb] kinetics were determined during subsequent submaximal step exercise. The Vo(2max) was significantly reduced (P < 0.05) in individuals with T2D compared with CON (1.98 ± 0.43 vs. 2.72 ± 0.40 l/min, respectively) but, surprisingly, Vo(2) kinetics was not different in T2D compared with CON (phase II time constant: 43 ± 17 vs. 41 ± 12 s, respectively). The Δ[HHb]/ΔVo(2) was significantly higher in T2D compared with CON (235 ± 99 vs. 135 ± 33 AU·l(-1)·min(-1); P < 0.05). Despite a lower Vo(2max), Vo(2) kinetics is not different in older T2D compared with healthy age-matched control participants. The elevated Δ[HHb]/ΔVo(2) in T2D individuals possibly indicates a compromised muscle blood flow that mandates a greater O(2) extraction during exercise. Longer disease duration may result in adaptations in the O(2) extraction capabilities of individuals with T2D, thereby mitigating the expected age-related slowing of Vo(2) kinetics.
authors.affiliation: School of Sport and Health Sciences, St. Luke's Campus, Univ. of Exeter, Devon, UK. d.p.wilkerson@ex.ac.uk
authors.forename: D P
authors.initials: DP
authors.lastname: Wilkerson
authors.forename: D C
authors.initials: DC
authors.lastname: Poole
authors.forename: A M
authors.initials: AM
authors.lastname: Jones
authors.forename: J
authors.initials: J
authors.lastname: Fulford
authors.forename: D M
authors.initials: DM
authors.lastname: Mawson
authors.forename: C I
authors.initials: CI
authors.lastname: Ball
authors.forename: A C
authors.initials: AC
authors.lastname: Shore
mesh_terms: D000222:Adaptation, Physiological; D000367:Age Factors; D000368:Aged; D001642:Bicycling; D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2 / Q000378:metabolism* / Q000503:physiopathology; D015444:Exercise; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism* / Q000503:physiopathology; D010101:Oxygen Consumption; D011659:Pulmonary Gas Exchange; D012039:Regional Blood Flow
chemical_list: D006454:Hemoglobins; C100003:deoxyhemoglobin