title: Mice with elevated muscle glycogen stores do not have improved exercise performance.
abstract: Skeletal muscle glycogen is considered to be an important source of energy for contraction and increasing the level of the glucose polymer is generally thought to improve exercise performance in humans. A genetically modified mouse model (GSL30), which overaccumulates glycogen due to overexpression of a hyperactive form of glycogen synthase, was used to examine whether increasing the level of the polysaccharide enhances the ability of mice to run on a treadmill. The skeletal muscle of the GSL30 mice had large deposits of glycogen. There were no significant increases in the work performed by GSL30 mice as compared to their respective wild type littermates when exercised to exhaustion. The amount of muscle glycogen utilized by GSL30 mice, however, was greater, while the amount of liver glycogen consumed during exhaustive exercise was less than wild type animals. This result suggests that increased muscle glycogen stores do not necessarily improve exercise performance in mice.
authors.affiliation: Department of Biochemistry and Molecular Biology and Center for Diabetes Research, Indiana University School of Medicine, Indianapolis, IN 46202-5122, USA.
authors.forename: Bartholomew A
authors.initials: BA
authors.lastname: Pederson
authors.forename: Carlie R
authors.initials: CR
authors.lastname: Cope
authors.forename: Jose M
authors.initials: JM
authors.lastname: Irimia
authors.forename: Jill M
authors.initials: JM
authors.lastname: Schroeder
authors.forename: Beth L
authors.initials: BL
authors.lastname: Thurberg
authors.forename: Anna A
authors.initials: AA
authors.lastname: Depaoli-Roach
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Roach
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D005080:Exercise Test; D006003:Glycogen / Q000378:metabolism*; D006006:Glycogen Synthase / Q000235:genetics / Q000378:metabolism; D019344:Lactic Acid / Q000097:blood; D008099:Liver / Q000378:metabolism; D051379:Mice; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism* / Q000502:physiology; D010805:Physical Conditioning, Animal / Q000502:physiology*
chemical_list: D001786:Blood Glucose; D019344:Lactic Acid; D006003:Glycogen; D006006:Glycogen Synthase