title: Exercise training induces similar elevations in the activity of oxoglutarate dehydrogenase and peak oxygen uptake in the human quadriceps muscle.
abstract: During exercise involving a small muscle mass, peak oxygen uptake is thought to be limited by peripheral factors, such as the degree of oxygen extraction from the blood and/or mitochondrial oxidative capacity. Previously, the maximal activity of the Krebs cycle enzyme oxoglutarate dehydrogenase has been shown to provide a quantitative measure of maximal oxidative metabolism, but it is not known whether the increase in this activity after a period of training reflects the elevation in peak oxygen consumption. Fourteen subjects performed one-legged knee extension exercise for 5-7 weeks, while the other leg remained untrained. Thereafter, the peak oxygen uptake by the quadriceps muscle was determined for both legs, and muscle biopsies were taken for assays of maximal enzyme activities (at 25°C). The peak oxygen uptake was 26% higher in the trained than in the untrained muscle (395 vs. 315 ml min(-1) kg(-1), respectively; P<0.01). The maximal activities of the Krebs cycle enzymes in the trained and untrained muscle were as follows: citrate synthase, 22.4 vs. 18.2 μmol min(-1) g(-1) (23%, P<0.05); oxoglutarate dehydrogenase, 1.88 vs. 1.54 μmol min(-1) g(-1) (22%, P<0.05); and succinate dehydrogenase, 3.88 vs. 3.28 μmol min(-1) g(-1) (18%, P<0.05). The difference between the trained and untrained muscles with respect to peak oxygen uptake (80 ml min(-1) kg(-1)) corresponded to a flux through the Krebs cycle of 1.05 μmol min(-1) g(-1), and the corresponding difference in oxoglutarate dehydrogenase activity (at 38°C) was 0.83 μmol min(-1) g(-1). These parallel increases suggest that there is no excess mitochondrial capacity during maximal exercise with a small muscle mass.
authors: The Swedish School of Sport and Health Sciences, Stockholm, Sweden. eva.blomstrand@gih.se
authors: Eva
authors: E
authors: Blomstrand
authors: Peter
authors: P
authors: Krustrup
authors: Hans
authors: H
authors: Søndergaard
authors: Göran
authors: G
authors: Rådegran
authors: José A L
authors: JA
authors: Calbet
authors: Bengt
authors: B
authors: Saltin
references: Acta Physiol Scand. 1999 Aug;166(4):309-18
references: 10468668
references: J Histochem Cytochem. 1969 Jun;17(6):431-2
references: 4241223
references: Biochem J. 1976 Mar 15;154(3):689-700
references: 8036
references: J Physiol. 1997 Jun 1;501 ( Pt 2):455-60
references: 9192316
references: Am J Physiol Endocrinol Metab. 2001 Jun;280(6):E956-64
references: 11350777
references: Acta Physiol Scand. 1977 Jan;99(1):91-7
references: 190867
references: J Exp Biol. 1985 Mar;115:319-31
references: 4031773
references: J Physiol. 2004 Aug 15;559(Pt 1):335-45
references: 15235098
references: J Appl Physiol (1985). 2000 Sep;89(3):1033-8
references: 10956347
references: Am J Physiol. 1992 Oct;263(4 Pt 2):R891-9
references: 1415803
references: Biochem J. 1977 May 15;164(2):349-55
references: 880242
references: Med Sci Sports Exerc. 1996 Oct;28(10):1327-30
references: 8897392
references: Physiol Rev. 1996 Apr;76(2):371-423
references: 8618961
references: J Appl Physiol (1985). 1985 Aug;59(2):320-7
references: 4030584
references: J Exp Biol. 1985 Mar;115:345-54
references: 4031774
references: J Appl Physiol (1985). 2004 Nov;97(5):1796-802
references: 15208296
references: J Physiol. 2008 Jan 1;586(1):151-60
references: 17991697
references: Histochem Cell Biol. 1997 Feb;107(2):169-74
references: 9062802
references: Biochem Biophys Res Commun. 1970 Sep 30;40(6):1368-73
references: 4327015
references: Pflugers Arch. 2004 Oct;449(1):56-65
references: 15290298
references: J Physiol. 2005 Jul 1;566(Pt 1):273-85
references: 15860533
references: J Physiol. 2000 Apr 15;524 Pt 2:603-15
references: 10766936
references: J Appl Physiol (1985). 1999 Dec;87(6):2375-80
references: 10601192
references: Biosci Rep. 1983 Dec;3(12):1149-53
references: 6230115
references: J Physiol. 1985 Sep;366:233-49
references: 4057091
references: J Appl Physiol (1985). 2006 Feb;100(2):744-5
references: 16421282
references: J Physiol. 2006 Sep 15;575(Pt 3):901-11
references: 16825308
references: Med Sci Sports Exerc. 2009 Dec;41(12):2136-44
references: 19915506
references: J Histochem Cytochem. 1970 Sep;18(9):670-2
references: 4249441
references: Biochem J. 1981 Dec 15;200(3):701-3
references: 7342978
references: Am J Physiol Endocrinol Metab. 2001 Feb;280(2):E301-7
references: 11158934
references: Med Sci Sports Exerc. 2000 Jan;32(1):85-8
references: 10647533
references: J Physiol. 1969 Oct;204(2):63P-66P
references: 5824654
references: J Physiol. 1986 Dec;381:111-8
references: 2957491
references: J Physiol. 2004 Jul 1;558(Pt 1):319-31
references: 15121799
references: Acta Physiol Scand Suppl. 1956;37(126):1-79
references: 13339458
references: J Appl Physiol (1985). 1999 Mar;86(3):1048-53
references: 10066722
references: Eur J Appl Physiol Occup Physiol. 1987;56(5):516-21
references: 3653091
references: J Appl Physiol (1985). 2006 Feb;100(2):745-7; discussion 747-8
references: 16468127