title: A short period of high-intensity interval training improves skeletal muscle mitochondrial function and pulmonary oxygen uptake kinetics.
abstract: The aim of the present study was to examine whether improvements in pulmonary oxygen uptake (V̇o2) kinetics following a short period of high-intensity training (HIT) would be associated with improved skeletal muscle mitochondrial function. Ten untrained male volunteers (age 26 ± 2 yr; mean ± SD) performed six HIT sessions (8-12 × 60 s at incremental test peak power; 271 ± 52 W) over a 2-wk period. Before and after the HIT period, V̇o2 kinetics was modeled during moderate-intensity cycling (110 ± 19 W). Mitochondrial function was assessed with high-resolution respirometry (HRR), and maximal activities of oxidative enzymes citrate synthase (CS) and cytochrome c oxidase (COX) were accordingly determined. In response to HIT, V̇o2 kinetics became faster (τ: 20.4 ± 4.4 vs. 28.9 ± 6.1 s; P < 0.01) and fatty acid oxidation (ETFP) and leak respiration (LN) both became elevated (P < 0.05). Activity of CS and COX did not increase in response to training. Both before and after the HIT period, fast V̇o2 kinetics (low τ values) was associated with large values for ETFP, electron transport system capacity (ETS), and electron flow specific to complex II (CIIP) (P < 0.05). Collectively, these findings support that selected measures of mitochondrial function obtained with HRR are important for fast V̇o2 kinetics and better markers than maximal oxidative enzyme activity in describing the speed of the V̇o2 response during moderate-intensity exercise.
authors: Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark; Team Danmark (Danish Elite Sport Organization), Copenhagen, Denmark;
authors: Peter M
authors: PM
authors: Christensen
authors: Health and Physical Education, School of Teaching and Learning, Western Carolina University, Cullowhee, North Carolina; Department of Physical Therapy, Western Carolina University, Cullowhee, North Carolina; and.
authors: Robert A
authors: RA
authors: Jacobs
authors: Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark;
authors: Thomas
authors: T
authors: Bonne
authors: Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland.
authors: Daniela
authors: D
authors: Flück
authors: Department of Nutrition, Exercise and Sports, Section of Integrated Physiology, University of Copenhagen, Copenhagen, Denmark;
authors: Jens
authors: J
authors: Bangsbo
authors: Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland carsten.lundby@access.uzh.ch.
authors: Carsten
authors: C
authors: Lundby
mesh_terms: D000328:Adult; D002950:Citrate (si)-Synthase / Q000378:metabolism; D042963:Electron Transport Complex II / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D000072696:High-Intensity Interval Training / Q000379:methods; D006801:Humans; D007700:Kinetics; D008168:Lung / Q000378:metabolism / Q000502:physiology*; D008297:Male; D008928:Mitochondria / Q000378:metabolism / Q000502:physiology*; D018482:Muscle, Skeletal / Q000378:metabolism / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*
chemical_list: D042963:Electron Transport Complex II; D003576:Electron Transport Complex IV; D002950:Citrate (si)-Synthase; D010100:Oxygen
keywords: OXPHOS; cycling economy; enzyme activity; high-intensity training; oxygen uptake