The influence of sex on fiber-specific indices of oxidative capacity in human skeletal muscle

Bailleul, Celine, Hodson, Nathan ORCID: https://orcid.org/0000-0003-1330-4030, Abou Sawan, Sidney, Kumbhare, Dinesh ORCID: https://orcid.org/0000-0003-3889-7557, Moore, Daniel R. ORCID: https://orcid.org/0000-0001-5865-4398 and Gillen, Jenna B. ORCID: https://orcid.org/0000-0001-7974-5395 (2025) The influence of sex on fiber-specific indices of oxidative capacity in human skeletal muscle. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 329 (1). R70-R80. ISSN 1522-1490

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Abstract

Research suggests that skeletal muscle oxidative capacity in mixed-fiber muscle homogenates is greater in females than in males. In healthy, untrained individuals, we demonstrate by fiber-specific immunofluorescence that females have a greater proportionate area of type I muscle fibers but no difference in mitochondrial content or capillarization of type I or II fibers compared to males. These findings suggest that although females display a more oxidative fiber type composition, sex does not influence muscle fiber-specific oxidative capacity.