Jacobs 2012 Abstract Bioblast
|Jacobs R, Lundby C (2012) Mitochondria express enhanced quality as well as quantity in parallel with aerobic fitness across recreationally active individuals up to elite athletes. Mitochondr Physiol Network 17.12.|
Event: Bioblast 2012
Differences in skeletal muscle respiratory capacity parallel that of aerobic fitness. It is unknown whether mitochondrial content, alone, can fully account for these differences in skeletal muscle respiratory capacity. The aim of the present study was to examine quantitative and qualitative mitochondrial characteristics across four different groups (N = 6 each), separated by cardiorespiratory fitness. High-resolution respirometry was performed on muscle samples to compare respiratory capacity and efficiency in active (AT), well-trained (WT), highly-trained (HT), and elite (ET) individuals. Maximal exercise capacity (ml O2 min-1 kg-1) differed across all groups with mean ± SD values of 51 ± 4, 64 ± 5, 71 ± 2, and 77 ± 3, respectively. Mitochondrial content assessed by citrate synthase activity was higher in ET compared to AT and WT (29 ± 7 versus 19 ± 4 and 16 ± 4 nmol min-1 mg ww-1, respectively). When normalizing mitochondrial respiration to content, the respiratory capacities during maximal fatty acid oxidation (p = 0.003), maximal State 3 respiration (P = 0.021), and total electron transfer system capacity (P = 0.008) varied between groups. The coupling efficiency of β-oxidation, however, was not affected by level of fitness. These data demonstrate the quantitative and qualitative differences that exist in skeletal muscle mitochondrial respiratory capacity and efficiency across individuals that differ in aerobic capacity. Mitochondrial-specific respiration capacities during β-oxidation, maximal oxidative phosphorylation, and electron transport system capacity all improve in parallel with aerobic capacity, independent of mitochondrial content in human skeletal muscle.
- Schwerzmann K, Hoppeler H, Kayar SR, and Weibel ER (1989) Oxidative capacity of muscle and mitochondria: correlation of physiological, biochemical, and morphometric characteristics. Proc Natl Acad Sci U S A 86: 1583-1587. Open Access
- Befroy DE, Petersen KF, Dufour S, Mason GF, Rothman DL, and Shulman GI (2008) Increased substrate oxidation and mitochondrial uncoupling in skeletal muscle of endurance-trained individuals. Proc Natl Acad Sci U S A 105: 16701-16706. Open Access
- Jacobs RA, Rasmussen P, Siebenmann C, Díaz V, Pesta D, Gnaiger E, Nordsborg NB, Robach P, Lundby C (2011) Determinants of time trial performance and maximal incremental exercise in highly trained endurance athletes. J Appl Physiol 111: 1422–1430.
• Mitochondria, Exercise, Skeletal muscle, Fat oxidation MiPNetLab: CH Zurich Lundby C
Labels: MiParea: Respiration, mt-Biogenesis;mt-density, Exercise physiology;nutrition;life style Mammal;model: Human Tissue;cell: Skeletal muscle Preparation: Permeabilized cells Enzyme: TCA cycle and matrix dehydrogenases Regulation: Fatty acid Coupling state: LEAK, OXPHOS, ETS Substrate state: CI, CII, FAO, CIII, CIV, CI&II HRR: Oxygraph-2k
Zurich Center for Integrative Human Physiology (ZIHP), Zurich, Switzerland; Email: firstname.lastname@example.org;
Institute of Veterinary Physiology, Vetsuisse Faculty, University of Zurich, Switzerland;
Institute of Physiology, University of Zurich, Switzerland