title: Effects of short-term training and detraining on VO2 kinetics: Faster VO2 kinetics response after one training session.
abstract: This study examined the time course of short-term training and detraining-induced changes in oxygen uptake ( V ˙ O 2 ) kinetics. Twelve men (24 ± 3 years) were assigned to either a 50% or a 70% of V ˙ O 2 m a x training intensity (n = 6 per group). V ˙ O 2 was measured breath-by-breath. Changes in deoxygenated-hemoglobin concentration (Δ[HHb]) were measured by near-infrared spectroscopy. Moderate-intensity exercise on-transient V ˙ O 2 and Δ[HHb] were modeled with a mono-exponential and normalized (0-100% of response) and the [ H H b ] / V ˙ O 2 ratio was calculated. Similar changes in time constant of V ˙ O 2 ( t V ˙ O 2 ) were observed in both groups. The combined group mean for t V ˙ O 2 decreased ∼14% (32.3 to 27.9 s, P < 0.05) after one training session with a further ∼11% decrease (27.9 to 24.8 s, P < 0.05) following two training sessions. The t V ˙ O 2 p remained unchanged throughout the remaining of training and detraining. A significant "overshoot" in the [ H H b ] / V ˙ O 2 ratio was decreased (albeit not significant) after one training session, and abolished (P < 0.05) after the second one, with no overshoot observed thereafter. Speeding of V ˙ O 2 kinetics was remarkably quick with no further changes being observed with continuous training or during detraining. Improve matching of local O2 delivery to O2 utilization is a mechanism proposed to influence this response.
authors.affiliation: Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.
authors.forename: J M
authors.initials: JM
authors.lastname: Murias
authors.affiliation: Canadian Centre for Activity and Aging, Ontario, London, Canada.|School of Kinesiology, University of Western Ontario, London, ON, Canada.
authors.forename: J A
authors.initials: JA
authors.lastname: Edwards
authors.affiliation: Canadian Centre for Activity and Aging, Ontario, London, Canada.|School of Kinesiology, University of Western Ontario, London, ON, Canada.
authors.forename: D H
authors.initials: DH
authors.lastname: Paterson
mesh_terms: D000328:Adult; D018493:Cardiovascular Deconditioning / Q000502:physiology; D005080:Exercise Test; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008297:Male; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption; D064797:Physical Conditioning, Human / Q000379:methods / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology*; D011659:Pulmonary Gas Exchange; D052097:Quadriceps Muscle / Q000378:metabolism; D055815:Young Adult
chemical_list: D006454:Hemoglobins; D010100:Oxygen
keywords: O2 extraction; Oxidative phosphorylation; moderate-intensity exercise; near-infrared spectroscopy