title: Fiber type composition of the vastus lateralis muscle of young men and women.
abstract: This study presents data collected over the past 10 years on the muscle fiber type composition of the vastus lateralis muscle of young men and women. Biopsies were taken from the vastus lateralis muscle of 55 women (21.2+/-2.2 yr) and 95 men (21.5+/-2.4 yr) who had volunteered to participate in various research projects. Six fiber types (I, IC, IIC, IIA, IIAB, and IIB) were classified using mATPase histochemistry, and cross-sectional area was measured for the major fiber types (I, IIA, and IIB). Myosin heavy chain (MHC) content was determined electrophoretically on all of the samples from the men and on 26 samples from the women. With the exception of fiber Type IC, no significant differences were found between men and women for muscle fiber type distribution. The vastus lateralis muscle of both the men and women contained approximately 41% I, 1% IC, 1% IIC, 31% IIA, 6% IIAB, and 20% IIB. However, the cross-sectional area of all three major fiber types was larger for the men compared to the women. In addition, the Type IIA fibers were the largest for the men, whereas the Type I fibers tended to be the largest for the women. Therefore, gender differences were found with regard to the area occupied by each specific fiber type: IIA>I>IIB for the men and I>IIA>IIB for the women. These data establish normative values for the mATPase-based fiber type distribution and sizes in untrained young men and women.
authors.affiliation: Department of Biomedical Sciences, College of Osteopathic Medicine, Ohio University, Athens, Ohio 45701, USA. staron@ohiou.edu
authors.forename: R S
authors.initials: RS
authors.lastname: Staron
authors.forename: F C
authors.initials: FC
authors.lastname: Hagerman
authors.forename: R S
authors.initials: RS
authors.lastname: Hikida
authors.forename: T F
authors.initials: TF
authors.lastname: Murray
authors.forename: D P
authors.initials: DP
authors.lastname: Hostler
authors.forename: M T
authors.initials: MT
authors.lastname: Crill
authors.forename: K E
authors.initials: KE
authors.lastname: Ragg
authors.forename: K
authors.initials: K
authors.lastname: Toma
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000328:Adult; D000886:Anthropometry; D001707:Biopsy, Needle; D001823:Body Composition; D005260:Female; D006801:Humans; D008297:Male; D018656:Muscle Fibers, Fast-Twitch / Q000166:cytology* / Q000201:enzymology; D018657:Muscle Fibers, Slow-Twitch / Q000166:cytology* / Q000201:enzymology; D018482:Muscle, Skeletal / Q000166:cytology* / Q000201:enzymology; D018995:Myosin Heavy Chains / Q000032:analysis / Q000378:metabolism; D012016:Reference Values; D012737:Sex Factors
chemical_list: D000251:Adenosine Triphosphatases; D018995:Myosin Heavy Chains