title: Similar pattern of change in V̇o2kinetics, vascular function, and tissue oxygen provision following an endurance training stimulus in older and young adults.
abstract: The purpose of this study was to examine the time course of changes in the oxygen uptake (V̇o2) kinetics response subsequent to short-term exercise training (i.e., 24, 48, 72, and 120 h posttraining) and examine the relationship with the time course of changes in microvascular [deoxygenated hemoglobin concentration ([HHb])-to-V̇o2ratio ([HHb])/V̇o2)] and macrovascular [flow-mediated dilation (FMD)] O2delivery to the active tissues/limbs. Seven healthy older [OA; 74 ± 6 (SD) yr] and young men (YA; 25 ± 3 yr) completed three endurance cycling exercise training sessions at 70% V̇o2peakModerate-intensity exercise on-transient V̇o2(measured breath by breath) and [HHb] (measured by near-infrared spectroscopy) were modeled with a monoexponential and normalized (0-100% of response), and the [HHb])/V̇o2was calculated. Ultrasound-derived FMD of the popliteal artery was assessed after 5 min of cuff occlusion. %FMD was calculated as the greatest percent change in diameter from baseline. Time constant of V̇o2(τV̇o2) was significantly reduced in both OA (~18%) and YA (~23%) at 24 h (P< 0.001) posttraining and remained decreased at 48 h before returning toward pretraining (PRE) values. Both groups showed a significant decrease in the [HHb])/V̇o2at 24, 48, and 72 h (P= 0.001, 0.01, and 0.03, respectively) posttraining before returning toward PRE values at 120 h. %FMD followed a similar time course to that of changes in the [HHb])/V̇o2, being significantly greater in both OA (by ~64%) and YA (by ~26%) at 24 h (P< 0.001), remaining increased at 48 and 72 h (P= 0.02 and 0.03, respectively), and returning toward PRE values at 120 h. These data suggest the rate of adjustment of V̇o2may be constrained by O2availability in the active tissues.
authors.affiliation: Canadian Centre for Activity and Aging, London, Ontario, Canada.|School of Kinesiology, The University of Western Ontario, London, Ontario, Canada; and.
authors.forename: Kaitlin M
authors.initials: KM
authors.lastname: McLay
authors.affiliation: School of Kinesiology, The University of Western Ontario, London, Ontario, Canada; and jmmurias@ucalgary.ca.|Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Juan M
authors.initials: JM
authors.lastname: Murias
authors.affiliation: Canadian Centre for Activity and Aging, London, Ontario, Canada.|School of Kinesiology, The University of Western Ontario, London, Ontario, Canada; and.
authors.forename: Donald H
authors.initials: DH
authors.lastname: Paterson
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D000072696:High-Intensity Interval Training / Q000379:methods; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism; D010101:Oxygen Consumption / Q000502:physiology*; D064797:Physical Conditioning, Human / Q000379:methods; D010807:Physical Endurance / Q000502:physiology*
chemical_list: D010100:Oxygen
keywords: O2 extraction; V̇o2 kinetics; flow-mediated dilation; near-infrared spectroscopy; short-term exercise training