Document Type
Journal Article
Publication Title
Clinical Anatomy
PubMed ID
37424380
Publisher
Wiley
School
School of Medical and Health Sciences
RAS ID
62027
Funders
Open access publishing facilitated by Edith Cowan University, as part of the Wiley - Edith Cowan University agreement via the Council of Australian University Librarians.
Abstract
Biopsies have been acquired from living men and women to determine proportions of Type I (slow-twitch) and II (fast-twitch) skeletal muscle fibers since the 1970s. Sex differences have been assumed but the literature has not been submitted to meta-analysis. Here, the aim was to generate effect sizes of sex differences in muscle fiber cross-sectional areas, distribution percentages, and area percentages. Data from 2875 men and 2452 women, who participated in 110 studies, were analyzed. Myofibrillar adenosine triphosphatase histochemistry was used in 71.8% of studies to classify fibers as Type I, II, IIA, and/or IIX; immunohistochemistry, immunofluorescence, or sodium dodecyl sulfate-polyacrylamide gel electrophoresis were used in 35.4% of studies to similarly classify myosin heavy chain (MHC) isoform content. Most studies involved biopsies from vastus lateralis (79.1%) in healthy individuals (92.7%) between 18 and 59 years old (80.9%). Men exhibited greater cross-sectional areas for all fiber types (g = 0.40–1.68); greater distribution percentages for Type II, MHC II, IIA, IIX fibers (g = 0.26–0.34); greater area percentages for Type II, IIA, MHC IIA, IIX fibers (g = 0.39–0.93); greater Type II/I and Type IIA/I fiber area ratios (g = 0.63, 0.94). Women exhibited greater Type I and MHC I distribution percentages (g = −0.13, −0.44); greater Type I and MHC I area percentages (g = −0.53, −0.69); greater Type I/II fiber area ratios (g = −1.24). These data, which represent the largest repository of comparative muscle fiber type data from living men and women, can inform discussions about biological sex and its impact on pathologies and sports performance (e.g., explaining sex differences in muscle strength and muscle endurance).
DOI
10.1002/ca.24091
Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.
Comments
Nuzzo, J. L. (2023). Sex differences in skeletal muscle fiber types: A meta-analysis. Clinical Anatomy, 37(1), 81-91. https://doi.org/10.1002/ca.24091