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.

Quadriceps and hamstrings muscle control in athletic males and females

“…21,22 Females have been found to have a higher proportion of slow fibers in their muscles in a number of studies using quadriceps muscle biopsies or EMG power spectrum analyses; however, this finding has not been uniform. [23][24][25] Staron and colleagues 25 reported that while no significant difference in the number of slow and fast fibers was observed between sexes, females had a larger area of their vastus lateralis muscles occupied by slow fibers, whereas males had a larger area occupied by fast fibers. Males have also consistently been found to have fibers with larger cross-sectional areas than females.…”

Age-related decline in muscle mass and muscle function in Flemish Caucasians: a 10-year follow-up

“…There is some evidence that the proportional area of type I fibers is significantly greater in women compared to men and that men have larger fibers across most of the fiber types (Simoneau and Bouchard 1989;Staron et al 2000;Hunter 2014). Moreover, a decline in fiber size, of type Data are beta-coefficients.…”

Fadiga muscular entre séries de exercícios isocinéticos em mulheres jovens

“…Dentre eles destacam-se a diferença no sistema músculo esquelético, a morfologia e distribuição das fibras musculares, a ativação neural, a concentração de hormônios (STARON et al, 2000;PINCIVERO et al, 2001;ESBJÖRNSSON-LILJEDAHL et al, 2002;HUNTER et al, 2004b;WÜST et al, 2008).…”

“…Staron et al (2000) ressaltaram não haver diferenças entre os gêneros na distribuição das fibras musculares na musculatura vasto lateral do quadríceps. Em seu estudo, Staron et al (2000) demonstraram haver uma diferença no percentual de área ocupada pelos tipos de fibras musculares em homens e mulheres.…”

“…Staron et al (2000) ressaltaram não haver diferenças entre os gêneros na distribuição das fibras musculares na musculatura vasto lateral do quadríceps. Em seu estudo, Staron et al (2000) demonstraram haver uma diferença no percentual de área ocupada pelos tipos de fibras musculares em homens e mulheres. As mulheres exibem uma maior área ocupada pelas fibras de vermelhas (tipo I) e os homens apresentam uma maior área ocupada pelas fibras brancas (fibras IIA) (ESBJÖRNSSON-LILJEDAHL et al, 1999;STARON et al, 2000).…”