Kathleen Couillard – The Rumor Detector – Agence Science-Presse
At the Paris Olympics, some female athletes were barred from track and field events because of their elevated testosterone levels. But it is difficult to determine what constitutes a normal testosterone level in women.
Facts to Retain
– Official standards have varied over time
– There are wide variations among men
– Studies trying to measure athletic performance have left a lot to be desired
Do Women Produce Testosterone?
The ovaries and the adrenal glands produce testosterone in women, according to the Harvard Medical School’s website. This hormone affects reproduction, and plays a role in ovary function. Testosterone impacts bone strength and sexual behavior. It also influences moods and behavior in general, noted British biologist Daniel Kelly of the University of Sheffield Hallam in 2019.
On the other hand, low testosterone levels among women can trigger health problems such as decreased libido, fragile bones, difficulty concentrating, and depression. Low quantities are also associated with increased risks of cardiac disease, diabetes and obesity among both women and men.
Varying Standards
In racing events like the marathon, the 1,000 m and the 100 m, men generally have better results than do women by a margin of 10% to 12%, according to recent research on the impact of gender on athletic performance. This gap has historically served as the reason that track and field competitions are divided into men’s and women’s events, the Court of Arbitration for Sport noted in a 2014 judgement on the eligibility of female athletes.
World Athletics, the international sports body responsible for governing national athletics federations, attributes this superiority to testosterone. That’s why they have set a maximum threshold for women participating in women’s events. In 2010, it was 10 nmol/L (nanomoles per litre); then it was lowered to 5 nmol/L in 2018. This limit for women applies only to certain events: the 400 m, 400 m hurdles, 800 m, 1,500 m, and the 1,000 m. And since 2023, regulations stipulate that women with “sexual development variations” have to have a testosterone level inferior to 2.5 nmol/L. This rule applies to all track and field events.
Do Men Show Great Variations?
In childhood, testosterone levels are the same for girls and boys. This was the 2018 finding of a team of researchers under the direction of Stéphane Bermon of the Health and Science Department of World Athletics. After puberty, the quantity among young women increases, hitting a peak between the ages of 20 and 25. Generally, it stays below 2 nmol/L. Men produce about 15 times more testosterone than do women, these researchers reported.
Nonetheless, the experts don’t agree on what constitutes normal testosterone levels among men and women. For example, in 2014, a team of researchers under the direction of Peter Sonsken, a professor at King’s College London, analyzed the endocrine profiles of 639 athletes (454 men and 239 women). They observed that the testosterone profiles of men and women could occasionally overlap. Indeed, 13.7% of the women studied had levels above 2.7 nmol/L, and 16.5% of men had levels below 8.4 nmol/L.
The results differed in a literature review by Stéphane Bermon and his team in 2018: the concentration of testosterone in men varied between 7.7 nmol/L and 29.4 nmol/L, whereas among women, it fluctuated between 0 and 1.7 nmol/L.
These differing conclusions can be explained in part by the fact that these teams of researchers did not agree on when the best time to measure testosterone levels was: at rest, or after competition? Nor did they agree on the technique to use: mass spectrometry, or immunoassay? Nor on what individuals to study: the general population, or elite athletes only?
Various Causes?
A woman might have an elevated level of testosterone because of a medical condition causing an excessive production of typically masculine hormones. That’s called hyperandrogenism, Salt Lake City doctors explained in 2019. The main cause is polycystic ovary syndrome.
More rarely, some women may experience sexual development variations. For example, some have two X chromosomes, but overproduce testosterone, according to a 2020 American report on female athletes with sexual development variations. That’s the case for women who suffer from congenital adrenal hyperplasia.
On the other hand, some women have an X chromosome and a Y chromosome (characteristic of males among mammals), but a genetic mutation affects the synthesis of testosterone, which affects the formation of genital organs during development in the uterus. Other women may have androgen insensitivity. That means that even if an elevated quantity of testosterone is produced, the body doesn’t react to it, in whole or in part. In both cases, these women have what appear to be female genital organs at birth, even though they have a Y chromosome.
Does Testosterone Affect Sports Performance?
The role of testosterone in athletic performance is not yet fully understood. It is well known that taking testosterone supplements improves sports results. But the results are far less clear for naturally produced testosterone, according to a 2024 article on the impacts of gender on performance. Elsewhere, in its 2014 judgement, the Court of Arbitration for Sport concluded that World Athletics didn’t have enough evidence to apply its own rules on the matter.
To answer this criticism, World Athletics based its position on a 2017 article by Stéphane Bermon and his team. In this study, female athletes with testosterone levels in the top third of testosterone production performed better than those in the bottom third in the following events: the 400 m, 400 m hurdles, 800 m, hammer throw, and pole vault. The gap in results varied from 1.78% (800 m) to 4.53% (hammer throw).
That study has come under a lot of criticism. First of all, Dalhousie University law professor Maria Dugas argues that there is an appearance of conflict of interest, since the study was carried out by researchers paid by World Athletics. Secondly, two independent teams of scientific researchers (Franklin, 2018 and Sonksen, 2018) noted several statistical issues. Since the raw data was not made available, it was impossible for anyone to reproduce the results.
In reaction, Stéphane Bermon and his team redid certain statistical analyses and published the results in 2018. The performance gap was re-evaluated to be between 2.1% to 2.29%. Nonetheless, in 2019, researchers with access to some of the data noted that between 17% and 32% of the numbers used contained errors. They demanded that the 2017 article be retracted.
According to the Court of Arbitration for Sport, an advantage of 1% to 3% is marginal, since several other factors affect athletic performance.
In 2024, American researchers interested on the impact of gender on athletic performance noted that several psychological factors influence how muscles react to physical activity. Moreover, sociocultural factors may limit the possibilities for training and competition, and could affect female performance. This partly explains why women’s performance has improved more rapidly than men’s over the past 100 years, as barriers to female participation in sports have diminished.
Verdict
Women also produce testosterone, but less than do men. Nonetheless, any advantage women may gain from higher than average testosterone levels has still not been proven.
This article is part of the Rumor Detector series: click here for other articles.
- On the Reflet de Société website, April 4th, 2025
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