title: Training-induced acceleration of O(2) uptake on-kinetics precedes muscle mitochondrial biogenesis in humans.
abstract: The effects of 5 weeks of moderate-intensity endurance training on pulmonary oxygen uptake kinetics (V(O(2)) on-kinetics) were studied in 15 healthy men (mean ± SD: age 22.7 ± 1.8 years, body weight 76.4 ± 8.9 kg and maximal V(O(2)) 46.0 ± 3.7 ml kg(-1) min(-1)). Training caused a significant acceleration (P = 0.003) of V(O(2)) on-kinetics during moderate-intensity cycling (time constant of the 'primary' component 30.0 ± 6.6 versus 22.8 ± 5.6 s before and after training, respectively) and a significant decrease (P = 0.04) in the amplitude of the primary component (837 ± 351 versus 801 ± 330 ml min(-1)). No changes in myosin heavy chain distribution, muscle fibre capillarization, level of peroxisome proliferator-activated receptor γ coactivator 1α and other markers of mitochondrial biogenesis (mitochondrial DNA copy number, cytochrome c and cytochrome oxidase subunit I contents) in the vastus lateralis were found after training. A significant downregulation in the content of the sarcoplasmic reticulum ATPase 2 (SERCA2; P = 0.03) and a tendency towards a decrease in SERCA1 (P = 0.055) was found after training. The decrease in SERCA1 was positively correlated (P = 0.05) with the training-induced decrease in the gain of the V(O(2)) on-kinetics (ΔV(O(2)) at steady state/Δpower output). In the early stage of training, the acceleration in V(O(2)) on-kinetics during moderate-intensity cycling can occur without enhanced mitochondrial biogenesis or changes in muscle myosin heavy chain distribution and in muscle fibre capillarization. The training-induced decrease of the O(2) cost of cycling could be caused by the downregulation of SERCA pumps.
authors.affiliation: Department of Physiology and Biochemistry, Faculty of Rehabilitation, University School of Physical Education, Kraków, Poland. jerzy.zoladz@awf.krakow.pl
authors.forename: Jerzy A
authors.initials: JA
authors.lastname: Zoladz
authors.forename: Bruno
authors.initials: B
authors.lastname: Grassi
authors.forename: Joanna
authors.initials: J
authors.lastname: Majerczak
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Szkutnik
authors.forename: Michał
authors.initials: M
authors.lastname: Korostyński
authors.forename: Janusz
authors.initials: J
authors.lastname: Karasiński
authors.forename: Wincenty
authors.initials: W
authors.lastname: Kilarski
authors.forename: Bernard
authors.initials: B
authors.lastname: Korzeniewski
mesh_terms: D000054:Acceleration; D000328:Adult; D003576:Electron Transport Complex IV / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D006801:Humans; D007700:Kinetics; D008297:Male; D008931:Mitochondria, Muscle / Q000378:metabolism*; D063269:Mitochondrial Turnover / Q000502:physiology; D018482:Muscle, Skeletal / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D055815:Young Adult
chemical_list: D003576:Electron Transport Complex IV; D010100:Oxygen