Myosin heavy chain isoform distribution in single fibres of bodybuilders.
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.
Kesidis
Nikolaos
N
Physical Education and Sports Science, Aristotle University of Thessaloniki, Thessaloniki, Greece.
Metaxas
Thomas I
TI
Vrabas
Ioannis S
IS
Stefanidis
Panagiotis
P
Vamvakoudis
Efstratios
E
Christoulas
Kosmas
K
Mandroukas
Athanasios
A
Balasas
Dimitrios
D
Mandroukas
Konstantinos
K
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*
D000251:Adenosine Triphosphatases; D018995:Myosin Heavy Chains