Biological Sex Differences in Muscle Mass and Testosterone

Testosterone Level Differences

Biological males have approximately 10-fold higher circulating testosterone levels than females, which directly drives substantially greater muscle mass, strength, and power, particularly after puberty 1, 2
Circulating testosterone concentrations in women are roughly 10-fold lower than those in men, driving sex-based physiological differences in body composition and physical performance 1, 2

In healthy young and older men, testosterone increases muscle mass and strength in a dose-dependent fashion, with appreciable hypertrophic response occurring within the physiologic range of circulating testosterone levels 1, 3, 4
Transgender men receiving testosterone therapy demonstrate a 15% increase in quadriceps cross-sectional area and thigh muscle volume, with 6% increase in radiological density, along with improved performance on knee extensions and flexion 5
After 1 year of testosterone treatment, transgender men were able to equal or outperform cisgender men in numbers of pushups, situps, and run times 5

Respiratory muscle strength differences would be expected between healthy males and females given the overall muscle mass differences driven by testosterone 1, 6

High testosterone doses in women are inevitably associated with virilization, making it difficult to identify doses that yield muscle hypertrophy without masculinizing effects 1, 3, 4
Testosterone administration in men carries dose-dependent side effects including increased hemoglobin, decreased HDL cholesterol, and potential enhancement of prostate cancer growth 3, 4, 7
In female athletes, energy deficiency can disrupt normal hormonal function, potentially affecting testosterone levels and other endocrine markers 8