title: Muscle glycogen stores and fatigue.
abstract: Studies performed at the beginning of the last century revealed the importance of carbohydrate as a fuel during exercise, and the importance of muscle glycogen on performance has subsequently been confirmed in numerous studies. However, the link between glycogen depletion and impaired muscle function during fatigue is not well understood and a direct cause-and-effect relationship between glycogen and muscle function remains to be established. The use of electron microscopy has revealed that glycogen is not homogeneously distributed in skeletal muscle fibres, but rather localized in distinct pools. Furthermore, each glycogen granule has its own metabolic machinery with glycolytic enzymes and regulating proteins. One pool of such glycogenolytic complexes is localized within the myofibrils in close contact with key proteins involved in the excitation-contraction coupling and Ca2+ release from the sarcoplasmic reticulum (SR). We and others have provided experimental evidence in favour of a direct role of decreased glycogen, localized within the myofibrils, for the reduction in SR Ca2+ release during fatigue. This is consistent with compartmentalized energy turnover and distinctly localized glycogen pools being of key importance for SR Ca2+ release and thereby affecting muscle contractility and fatigability.
authors: N. Ørtenblad: Institute of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, DK-5230 Odense M, Denmark. nortenblad@health.sdu.dk.
authors: Niels
authors: N
authors: Ørtenblad
authors: Håkan
authors: H
authors: Westerblad
authors: Joachim
authors: J
authors: Nielsen
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism*; D006801:Humans; D018763:Muscle Fatigue; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology
chemical_list: D006003:Glycogen; D002118:Calcium
references: Am J Physiol Cell Physiol. 2002 Jun;282(6):C1306-12
references: 11997245
references: Acta Physiol Scand. 1988 May;133(1):97-100
references: 3227908
references: Acta Physiol (Oxf). 2010 Aug;199(4):489-98
references: 20353490
references: Acta Physiol Scand. 1967 Oct-Nov;71(2):129-39
references: 5584522
references: J Physiol. 2007 Apr 15;580(Pt. 2):617-28
references: 17272352
references: J Muscle Res Cell Motil. 1984 Jun;5(3):315-32
references: 6746892
references: Appl Physiol Nutr Metab. 2013 Feb;38(2):91-9
references: 23438218
references: Cell Tissue Res. 1985;242(1):229-32
references: 2994885
references: Mol Cell Biochem. 2004 Jan-Feb;256-257(1-2):5-12
references: 14977166
references: FEBS J. 2012 Oct;279(20):3952-64
references: 22913516
references: J Appl Physiol (1985). 2006 Sep;101(3):695-706
references: 16709650
references: J Biol Chem. 1990 Mar 25;265(9):5258-66
references: 2318892
references: J Appl Physiol. 1971 Sep;31(3):416-22
references: 5111860
references: J Physiol. 2011 Feb 1;589(Pt 3):711-25
references: 21135051
references: J Muscle Res Cell Motil. 1992 Aug;13(4):420-35
references: 1401038
references: Am J Physiol. 1987 Mar;252(3 Pt 1):C328-34
references: 3030131
references: J Physiol. 2011 Jun 1;589(Pt 11):2871-85
references: 21486810
references: Am J Physiol Regul Integr Comp Physiol. 2006 Oct;291(4):R1100-10
references: 16690765
references: Am J Physiol. 1997 Feb;272(2 Pt 1):C550-9
references: 9124298
references: J Cell Biol. 1972 Aug;54(2):206-24
references: 5040859
references: J Physiol. 1997 Jan 1;498 ( Pt 1):17-29
references: 9023765
references: Biochemistry. 1992 Jan 21;31(2):377-84
references: 1731894
references: J Physiol. 1995 Dec 1;489 ( Pt 2):349-62
references: 8847631
references: Acta Physiol Scand. 1989 Mar;135(3):381-91
references: 2467521
references: Clin Exp Pharmacol Physiol. 2005 Sep;32(9):749-56
references: 16173932
references: Am J Physiol. 1999 Jul;277(1):E176-86
references: 10409142
references: J Cell Biol. 1968 Jul;38(1):130-50
references: 5691969
references: Physiol Rev. 2008 Jan;88(1):287-332
references: 18195089
references: Front Neuroenergetics. 2012 Mar 02;4:3
references: 22403540
references: J Physiol. 1992;451:205-27
references: 1403811
references: Acta Physiol Scand. 1967 Oct-Nov;71(2):140-50
references: 5584523
references: J Physiol. 1999 Aug 15;519 Pt 1:177-87
references: 10432348
references: J Physiol. 2012 Mar 1;590(5):1069-76
references: 22199166
references: Amino Acids. 2011 May;40(5):1271-96
references: 21448658
references: J Appl Physiol (1985). 1995 Jan;78(1):288-92
references: 7713825
references: J Appl Physiol (1985). 2002 Nov;93(5):1598-607
references: 12381743
references: J Muscle Res Cell Motil. 2006;27(5-7):259-74
references: 16874453
references: Am J Physiol Cell Physiol. 2007 Sep;293(3):C967-77
references: 17553934
references: Am J Physiol Endocrinol Metab. 2010 Dec;299(6):E1053-60
references: 20858747
references: Pflugers Arch. 2001 Apr;442(1):101-6
references: 11374056
references: J Physiol. 2009 Jul 15;587(Pt 14):3679-90
references: 19470780
references: Am J Physiol. 1997 Jul;273(1 Pt 1):C172-8
references: 9252454
references: J Appl Physiol. 1972 Oct;33(4):421-5
references: 4263085
references: Histochemistry. 1982;76(4):425-38
references: 7166509
references: J Biol Chem. 2009 Feb 13;284(7):4047-51
references: 18927076
references: Acta Physiol Scand. 1998 Mar;162(3):261-6
references: 9578371
references: J Muscle Res Cell Motil. 2000;21(5):481-9
references: 11129439