title: Myosin heavy chain isoform distribution in single fibres of bodybuilders.
abstract: The purpose of this study was to investigate the long-term effects of high intensity resistance training on myosin heavy chain (MHC) isoform composition of single fibres. Muscle biopsies were obtained from the right vastus lateralis of eight bodybuilders (BB) and seven physical education students (PES). Histochemical analyses were used to determine the fibre type distribution and the fibre cross-sectional area. MHC isoform composition of single fibres was determined with protein electrophoresis. The percentage of fibres expressing MHC IIA and MHC I/IIA was larger in BB (P < 0.05), while MHC IIX was completely absent (P < 0.05). In contrast, myofibrilar ATPase histochemistry only revealed a significantly lower percentage of type IIX fibres in BB (P < 0.05). The muscle fibre profile in the vastus lateralis muscle of BB may represent an adaptation based on the mechanical and biochemical demands of the long-term resistance training.
authors.affiliation: Physical Education and Sports Science, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Kesidis
authors.forename: Thomas I
authors.initials: TI
authors.lastname: Metaxas
authors.forename: Ioannis S
authors.initials: IS
authors.lastname: Vrabas
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Stefanidis
authors.forename: Efstratios
authors.initials: E
authors.lastname: Vamvakoudis
authors.forename: Kosmas
authors.initials: K
authors.lastname: Christoulas
authors.forename: Athanasios
authors.initials: A
authors.lastname: Mandroukas
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Balasas
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Mandroukas
mesh_terms: D000251:Adenosine Triphosphatases / Q000032:analysis / Q000378:metabolism; D000328:Adult; D001835:Body Weight; D004032:Diet; D006651:Histocytochemistry; D006801:Humans; D007536:Isomerism; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000378:metabolism* / Q000648:ultrastructure; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism* / Q000648:ultrastructure; D018995:Myosin Heavy Chains / Q000737:chemistry / Q000378:metabolism*; D014891:Weight Lifting / Q000502:physiology*
chemical_list: D000251:Adenosine Triphosphatases; D018995:Myosin Heavy Chains