Circulating Testosterone as the Hormonal Basis of Sex Differences in Athletic Performance

Abstract

Elite athletic competitions have separate male and female events due to men's physical advantages in strength, speed, and endurance so that a protected female category with objective entry criteria is required. Prior to puberty, there is no sex difference in circulating testosterone concentrations or athletic performance, but from puberty onward a clear sex difference in athletic performance emerges as circulating testosterone concentrations rise in men because testes produce 30 times more testosterone than before puberty with circulating testosterone exceeding 15-fold that of women at any age. There is a wide sex difference in circulating testosterone concentrations and a reproducible dose-response relationship between circulating testosterone and muscle mass and strength as well as circulating hemoglobin in both men and women. These dichotomies largely account for the sex differences in muscle mass and strength and circulating hemoglobin levels that result in at least an 8% to 12% ergogenic advantage in men. Suppression of elevated circulating testosterone of hyperandrogenic athletes results in negative effects on performance, which are reversed when suppression ceases. Based on the nonoverlapping, bimodal distribution of circulating testosterone concentration (measured by liquid chromatography-mass spectrometry)-and making an allowance for women with mild hyperandrogenism, notably women with polycystic ovary syndrome (who are overrepresented in elite athletics)-the appropriate eligibility criterion for female athletic events should be a circulating testosterone of <5.0 nmol/L. This would include all women other than those with untreated hyperandrogenic disorders of sexual development and noncompliant male-to-female transgender as well as testosterone-treated female-to-male transgender or androgen dopers.

Large divergence in testosterone concentrations between men and women: Frame of reference for elite athletes in sex‐specific competition in sports, a narrative review

“…Also, recent studies of androgen levels in elite athletes have suggested that female athletes with high testosterone levels, free or total, may have a significant competitive advantage over those with low testosterone levels. 15,46 Further controlled studies in both males 47 and females 48 have shown significant increases in muscle mass and strength, and a clear dose-response effect with administration of increasing amounts of exogenous testosterone.…”

Detection of testosterone doping in female athletes

“…While serum T concentration is increased in women with polycystic ovary syndrome (PCOS), the reference range for serum T concentration (by LC-MS) is 0 to 3.4 nmol/L, much lower than these extreme elevations 15. Furthermore, the mildly increased serum T concentrations due to PCOS are usually stable 15,18. Hence the extreme but transient elevation of serum T concentration is not consistent with, and excludes, any known female reproductive pathology as its cause.There is no known pharmacological explanation for the extreme elevations of serum T in females other than exogenous administration of T or pro-androgens (DHEA, androstenedione) unlike men in whom serum T concentrations can be increased by administration of hCG, GnRH analogs, anti-estrogens, and aromatase inhibitors 19.…”

Transwomen in elite sport: scientific and ethical considerations

“…In the remainder of this paper, we ask whether 10 nmol/L is too high because the normal healthy female testosterone range is 0–1.7 nmol/L 19 ii …”

“…It is well recognised that testosterone contributes to physiological factors including body composition, skeletal structure, and the cardiovascular and respiratory systems across the life span, with significant influence during the pubertal period 19. These physiological factors underpin strength, speed and recovery21with all three elements required to be competitive in almost all sports.…”

“…Transwomen are allowed to compete with testosterone levels just under 10 nmol/L. This is more than five times the upper testosterone level (1.7 nmol/L) of healthy, premenopausal elite cis-women athletes 19. Given that testosterone (as well as other elements stemming from Y-chromosome-dependent male physiology) provides an all-purpose benefit in sport, suggests that transwomen have a performance advantage.…”