Issue: October 2018
October 18, 2018
12 min read

New international sports rules concerning women’s hormone levels raise competitive, ethical concerns

Issue: October 2018
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The international governing body for athletics will require women with certain rare forms of hyperandrogenism to lower their natural testosterone level for at least 6 months prior to competing in races ranging from 400 m to 1 mile, according to new eligibility regulations released by the organization in April.

The new International Association of Athletics Federations (IAAF) requirements, slated to go into effect in November, state that any woman who is androgen-sensitive with a circulating testosterone level of at least 5 nmol/L must reduce her testosterone to less than 5 nmol/L with the use of an estrogen-containing medication, typically, hormonal contraceptives, and maintain that level continuously for as long as she wishes to remain eligible to compete in international competitions in restricted events, including the 400-m hurdles, races of 400-m, 800-m, 1500-m and 1-mile, and combined events over the same distances.

Athletes who do not meet the new conditions will not be eligible to compete in the female classification in the restricted events. According to the IAAF, such athletes will instead be eligible to compete only in national competitions, nonrestricted events in the female classification in international competitions, athletic events in the male classification or in any applicable intersex classification that may be offered.

Women with androgen disorders who have testoerone levels beyond the range of PCOS may have an advantage in athletic competitions, according to Andrea Dunaif, MD. Source: Mount Sinai Health System. Printed with permission.

The new rules raise several ethical and endocrine-related questions, according to experts, and are likely to only raise the stakes in the debate surrounding gender identity in sports.

“It doesn’t sit well that someone who is not doping — who is otherwise healthy but has a higher than usual level of one single hormone — should have to change her body in order to compete,” Tamara Wexler, MD, PhD, a neuroendocrinologist, reproductive endocrinologist and clinical associate professor at NYU Langone Medical Center in New York, told Endocrine Today. “It strays uncomfortably close to a ‘brave new world’ situation in which people with natural gifts are asked to alter their bodies toward the mean. More importantly, there is a focus on a single hormonal level, of unclear significance based on existing evidence, among the multitude of differences that can affect athletic ability.”

Testosterone, particularly in very low ranges, can be difficult to measure reliably, said Wexler, who is an Endocrine Today Editorial Board Member. The assays were not designed to measure such levels, according to Wexler.


“There are also concerns regarding how to accurately measure levels of bioavailable testosterone,” she said. “It’s just not that easy to do reliably.

Tamara Wexler

“[However,] my primary concern is the methodology and strength of the research upon which such a widespread policy is being based. The methodology used allows for association, but no causality.” (Editor’s note: See Wexler’s commentary “Study used to justify international women’s track and field eligibility rule leaves questions” in the Endocrine Today September issue.)

David Handelsman

But research shows there are distinct differences in testosterone levels between males and females, and those differences result in a competitive advantage for men, according to David J. Handelsman, MBBS, PhD, FRACP, an endocrinologist, foundation professor and director of the ANZAC Research Institute in Sydney.

“Although activists may make flamboyant arguments, this is no more complicated than using something like an oral contraceptive,” Handelsman, whose research was referenced in the IAAF regulations, told Endocrine Today. “Segregated classifications in sport are widespread. There are age-group classifications. There are weight classifications. There are disability grade classifications. Athletes participating in a weight-classified sport must make weight. Lowering testosterone for the small number of women affected by these regulations is no different.”

Eligibility criteria

The new regulations replace the IAAF’s previous Hyperandrogenism Regulations, which set a testosterone threshold of 10 nmol/L, narrow their scope to certain track events and strengthen the restrictions applicable to women with disorders of sexual development (see sidebar). The regulations incorporate findings from several peer-reviewed studies assessing serum testosterone levels in women and men with and without disorders of sexual development, as well as peer-reviewed data from the IAAF World Championships in Athletics in Daegu (2011) and Moscow (2013).

“If you look at the normal testosterone range for females and for males, there is no overlap,” Stéphane Bermon, MD, PhD, director of health and science for the IAAF, told Endocrine Today. “And if there is an overlap, it is because there is a medical condition in the male, a medical condition in the female, or doping. If you want to guarantee a level playing field in female competition, with credibility, you have to make sure you do not have females who are not testosterone insensitive competing with females who have a testosterone level in the male range.

“There will always be criticisms because we previously drew the line at 10 nmol/L, but liquid chromatography-mass spectrometry results show that bringing the line to 5 nmol/L is reasonable,” Bermon said.


In explanatory notes accompanying the regulations, the IAAF noted that, absent a disorder of sexual development, a tumor or doping, no female would have serum testosterone level at or above 5 nmol/L; however, individuals with disorders of sexual development can have very high levels of natural testosterone, extending into and even beyond the normal male range.

“Our evidence and data show that testosterone, either naturally produced or artificially inserted into the body, provides significant performance advantages in female athletes,” Sebastian Coe, president of the IAAF, said in a press release announcing the new regulations. “The revised rules are not about cheating ... they are about leveling the playing field to ensure fair and meaningful competition.”

The IAAF added that there is broad medical and scientific consensus that individuals who are androgen-sensitive with very high levels of natural testosterone “can increase their muscle mass and strength, as well as their levels of circulating hemoglobin.”

“This is a scientifically done regulation, and that should be commended,” Andrea Dunaif, MD, chief of the Hilda and J. Gabrilove division of endocrinology, diabetes and bone disease at the Icahn School of Medicine at Mount Sinai and an Endocrine Today Editorial Board Member, said in an interview. “We know that once testosterone levels start to get up toward the male range, it has effects on muscle mass and red blood cell count and the effect can enhance athletic performance. It’s a difficult, fraught area because people with these disorders don’t choose to have them, but it does give them an endogenous performance enhancement, and that is not fair to the athletes who don’t have the higher testosterone.”

The regulations do not apply to all female athletes with hyperandrogenism.

“These criteria allow for women with PCOS to be considered as they are,” Handelsman said. “Individuals who are excluded include individuals with [disorders of sexual development] with conditions like 5alpha-reductase type 2 deficiency, where, even though they have ambiguous genitalia, but a minority live as women, they have testes that make male levels of testosterone after puberty, they even produce sperm that can be used in IVF to produce paternity. It’s not even common sense that they should be considered as female, even though a minority of them are brought up as female.”

A ‘significant competitive advantage’

Stéphane Bermon

The new IAAF rules are based, in part, on a study published in the British Journal of Sports Medicine in 2017. Bermon and colleagues analyzed 2,127 best competition times from elite athletes taking part in track and field events the 2011 (Daegu, South Korea) and 2013 (Moscow) IAAF World Championships (1,332 female scores; 795 male scores) as well as blood samples collected during a non-fasting state. Researchers assessed serum testosterone and androstenedione, measured via liquid chromatography-mass spectrometry. Free testosterone was calculated using the Sodergard formula. Athletes were stratified by one of seven competition groups: throwing events, jumping events, sprinting events, combined events, middle distance running and race walking, and were also classified by tertiles according to free testosterone concentration.


Among the elite male athletes, researchers observed no differences in performance when comparing the lowest vs. highest free testosterone tertiles. However, when compared with the lowest free testosterone tertile, female athletes in the highest free testosterone tertile demonstrated better performances in the 400-m, 400-m hurdles and 800-m races, with calculated differences of 2.73%, 2.78% and 1.78%, respectively. Additionally, female hammer throwers and pole vaulters in the highest free testosterone tertile also had a performance advantage, with calculated differences of 4.53% and 2.94%, respectively, when compared against female athletes in the lowest tertile.

“We matched both endocrine results from blood tests from women in two consecutive world championships in 2011 and 2013 and the respective performances of the athletes,” Bermon said. “For most of the events, we found no correlation; however, for some of them, we found some positive correlation. Surprisingly, findings were mostly concentrated to the 400-m, 800-m and 1,000-m races. The higher the testosterone level, the better the performance achieved. When we decided to improve our regulations, we took these findings into account.”

But some have since called the data into question. In a letter submitted to the British Journal of Sports Medicine on Aug. 2, Roger Pielke Jr., PhD, professor and the director of the Sports Governance Center at the Center for Science and Technology Policy Research at the University of Colorado Boulder, and colleagues called for the Bermon study to be retracted, noting Pielke and colleagues’ inability to reproduce the findings based on performance data publicly available from the events analyzed.

The researchers recreated data for the 400-m, 400-m hurdles, 800-m and 1,500-m races and identified three types of errors, including duplicated athletes, duplicated times and “phantom times,” in which no athlete could be found with the reported time for an event.

“Problematic data make up between 17% and 33% of the values used in the analysis for these four events,” Pielke and colleagues wrote. “Given the pervasiveness of these errors, we consider it likely that similar problems might be found in the data for the other 17 women’s events and 22 men’s events, and perhaps as well in the anonymous medical data, which are the basis for the study’s main conclusions regarding the performance effects of elevated testosterone levels.”

The researchers also raised concerns about the measurement of free testosterone vs. total testosterone and the lack of adjustment for multiple comparisons, suggesting any observed differences could be attributed to chance.


“Taking this last criticism first, we note that we presented an exploratory study, without any attempt to claim confirmatory results,” Bermon and colleagues wrote in the response. “In fact, the exploratory evidence presented in the study is strong, and correction for multiplicity may be too conservative. But we agree that the results should be put into context. At the type 1 error level of .05, we could expect one of 20 hypotheses tested to be significant merely by chance, that is, P < .05. In this study, we have observed significant correlations at the .05 level in five events, out of 21 events in total. Therefore, it is very unlikely that all these findings are caused by chance.”

In a statement, the IAAF said it will not be seeking a retraction of the 2017 study.

“In the second paper published in British Journal of Sports Medicine in 2018, we took into account most of the criticisms, and the conclusions remain the same,” Bermon said in an interview. “But, this is not the only paper the regulations are based on. We also have observational studies and other research showing athletes with 46,XY disorders of sexual development have a testosterone level in the male range and have an overt advantage in some of these races.”

Wexler, who also raised issues with the data, noted that analyzing testosterone levels across tertiles is not specific enough for comparing performances advantages.

“The suggestion of correlation is often used as justification for a study that would more carefully look at whether or not a relationship exists, but not as the basis for a policy decision or changing medical guidelines,” Wexler said.

Testosterone ranges

In a literature review published in August, Richard V. Clark, MD, PhD, FACP, a member of the board of directors for the U.S. Anti-Doping Agency, and colleagues compared testosterone levels associated with disorders of sexual development with reference to average testosterone levels in healthy men and women. The researchers noted that ranges of testosterone for genetic males with 5ARD2 and complete or partial androgen insensitivity syndrome are mostly within the normal male range and “well beyond the range for normal females,” whereas the range of testosterone levels in women with PCOS extends beyond the normal female range, but not into the normal male range.

“The weighted average lower limit of testosterone level in healthy males is 8.8 nmol/L, roughly four- to fivefold higher than the average upper limit of testosterone level in healthy females, 2 nmol/L,” the researchers wrote. “There is no continuum of testosterone levels from normal females to normal males.”

Lisa Campo-Engelstein

As children, genetic males with 5ARD2 and partial androgen insensitivity syndrome, in particular, may be raised either as boys or girls, depending on whether the female or male phenotype predominates, the researchers wrote. That choice has come into question in elite sports, the researchers noted, and recent cases have been highlighted in which genetic males with a 46,XY disorder of sexual development competed as females in women’s events. These competitors, they wrote, have been challenged as having a competitive advantage due to elevated testosterone levels in the normal male range.

“In sport, you have a classification of male and female events, and that’s because males, on average, are stronger, taller and tend to have greater endurance,” Handelsman said. “So, there is a protected category of female competition, and that needs an objective definition. That can’t be done based on gender, which is a subjective definition. It has to be based on the binary of sex, and despite claims to the contrary that sex isn’t binary, it is overwhelmingly binary in nature and in biology, with rare, rare exceptions.”

Ethical concerns

Lisa Campo-Engelstein, PhD, an associate professor at the Alden March Bioethics Institute at Albany Medical College, New York, who specializes in reproductive ethics, said the new regulations ask a thorny question: Who counts as a woman?

“We often resort to a form of genetic essentialism — that what your genes say is what you really are,” Campo-Engelstein told Endocrine Today. “Which is why I find it so interesting that this group claims they are in no way questioning women’s gender identity. Well, that is exactly what they are questioning. They are clearly saying that, if you are a woman with a disorder of sexual development, you are not the ‘right’ kind of woman, and we must modify you so that you can fit into what we consider a ‘real’ woman.’”

Campo-Engelstein called the stated options for ineligible women “humiliating.”

“They can either participate with this intervention, which feels a little coercive, or participate in the men’s events,” Campo-Engelstein said. “For someone who identifies as a woman, that is not a great option. Or, they can compete in intersex competition, which is a false option.”

Dunaif, who called the regulations “exceptionally selective,” said the science demonstrates there is a physical advantage with levels of testosterone beyond the range of women with androgen disorders like PCOS.

“Obviously, this is a difficult situation,” Dunaif said. “But I think you have to see if from a perspective of fairness to the competitors who don’t have elevated testosterone. It’s a unique situation. The counter-argument is there are all sorts of genetic variations. There are people who have myostatin-related muscle hypertrophy. Should these ‘freaks of nature’ not be allowed to compete?

“It is certainly an interesting, ethical medical debate,” Dunaif said. “It has a lot of implications in sports.”

The regulations, Wexler said, are troubling in part due to the focus on only women’s bodies.

“While wanting to ensure fairness is understandable, I find the focus on women’s hormones and physiology when a woman is better at something to be troubling,” Wexler said. The IAAF states that the organization is currently reviewing and updating regulations regarding transgender athletes who have undergone gender reassignment to participate in women’s competitions. – by Regina Schaffer


Disclosures: Bermon reports he is the director of health and science for the IAAF. Campo- Engelstein, Dunaif, Handelsman and Wexler report no relevant financial disclosures.

Click here to read the POINTCOUNTER, "Should men with symptoms of low testosterone — but without hypogonadism — be prescribed testosterone therapy?"