In early May, The Court of Arbitration for Sport (CAS) ruled in favor of new regulations proposed by the International Association of Athletics Federations (IAAF). These rules would prevent female athletes who are 46 XY DSD (i.e. have an X and a Y chromosome and differences in sexual development) from competing as women if their testosterone levels do not fall within a certain range. As I explained last month, this ruling will likely affect the eligibility of South African runner Caster Semenya. Semenya, the reigning women’s 800-meter Olympic gold medalist, later appealed the CAS decision to the Swiss Federal Tribunal. In early June, that court instructed the IAAF to suspend its DSD regulations until the court reached a final decision. So Semenya is eligible to race, at least for the time being.

While there is a case for separating athletes on the basis of testosterone, reviews of IAAF research on testosterone and performance cast doubt on its conclusions. Furthermore, there is evidence that the IAAF regulations were inspired in part by criticisms about Caster Semenya’s physical appearance and an effort to target her in particular.

Fairness Among Female Athletes

At its best, the debate on Semenya’s eligibility hinges on questions of fairness. The IAAF claims Semenya’s continued participation is unfair to other competitors, who do not possess elevated testosterone levels. Semenya and her supporters claim it is unfair to exclude someone who has always identified and competed as a woman. Semenya did not choose the traits in question, and these characteristics only become apparent through a blood test.

Caster Semenya at the 2012 Olympics (theconversation.com)

It is clear that men and women have different physical capabilities. The men’s 800-meter world record of 1:40.91 is almost thirteen seconds faster than the women’s world record. It is almost fourteen seconds faster than Semenya’s personal best. In their athletic primes, I would expect Michael Jordan to beat Diana Taurasi in a game of one-on-one. I would expect Roger Federer to defeat Serena Williams in a singles tennis match. Whether testosterone alone provides a significant boost in athletic ability is a different question.

Divisions in Sports

I do not take issue with the IAAF or any other sports governing body dividing athletes by certain traits. Weight divisions have long been accepted in sports like boxing and weightlifting. In most cases, differences in sex serve to level the playing field among male and female athletes. Yet athletes with DSDs present an infrequent but difficult challenge to these divisions.

I do not want to speculate about what specific traits Caster Semenya does or does not possess. As I explained last month, it is logical that she is 46 XY DSD, since the proposed IAAF regulations will affect her. Instead, let us consider a hypothetical athlete with an X and a Y chromosome (typically associated with males), female genitalia and elevated testosterone. Just considering this athlete ought to make it clear why many have called for doing away with binary descriptions of gender and highlight the difficulties in ensuring fairness for all athletes.

The IAAF’s Policy on Testosterone and the Research

Based on its research, the IAAF has decided to distinguish competitors with DSD by using testosterone levels. The IAAF regulations in question pertain to athletes with a DSD who have blood testosterone levels of 5 nanomoles per liter (nmol/L) or higher. Athletes who meet these criteria must reduce their testosterone below 5 nmol/L in order to compete in 400-meter races, 400-meter hurdle races, 800-meter races, 1500-meter races, one-mile races and all other track events from 400 meters to one mile.

These regulations are based on research led by Dr. Stéphane Bermon, the head of the IAAF’s Medical and Science Department. Bermon was the lead author of a 2017 paper which found that women in the highest tertile of testosterone performed significantly better than women in the lowest tertile of testosterone in the 400 meters, 400-meter hurdles, 800 meters, hammer throw and pole vault.

Questionable Research?

Given Bermon’s findings, one solution to the challenge posed by DSD athletes is to separate competitive divisions by testosterone, not sex. Rather than having male and female divisions, the IAAF could use blood test results to divide athletes into three categories: high-testosterone (equivalent to males with average testosterone levels), moderate-testosterone (equivalent to females with DSDs who have higher-than-average testosterone) and low-testosterone (equivalent to females with average testosterone levels). This approach might gain traction as society becomes more comfortable with fluid boundaries between genders.

But is testosterone an appropriate metric to distinguish athletes? A 2019 paper published in The International Sports Law Journal raised serious doubts about Bermon’s research.

Despite claims by the IAAF, the data in Bermon’s 2017 paper was not peer-reviewed. In reviewing a subset of the original data from the 2011 and 2013 World Championships, authors Roger Pielke, Ross Tucker and Erik Boye found several errors in the data. In particular, more than one race time was listed for some athletes in the dataset. The same time was repeated more than once for some individual athletes, and there were some phantom times not associated with any athlete. Furthermore, Bermon’s paper included times for athletes who were disqualified for doping. In all, Pielke et al. found errors in 17.2% to 32.8% of all the times compared for four races in the original study (400 meters, 400-meter hurdles, 800 meters and 1500 meters).

The IAAF and Bermon published a follow-up to the original study in 2018, with some, but not all, of the original errors corrected. In comparing the two IAAF studies, Pielke et al. found that in three of the eleven running events studied, the performance difference between the highest and lowest testosterone tertiles decreased from the 2017 to the 2018 paper. That is, correcting some of the data lessened the effect of testosterone claimed by Bermon and the IAAF.

Another review of Bermon’s work published in the British Journal of Sports Medicine in 2018 found that performing a test of significance on the published data did not indicate any advantage of high testosterone on performance. However, Bermon and the IAAF have not released the complete dataset from their research for scientific review.

Targeting Semenya

Let us set aside questions about the significance of the IAAF research. If we agree that males have a competitive advantage over females in many athletic competitions, then it makes sense to separate athletes by sex or by some factor (of which testosterone is one possibility) that is relevant to the performance differences observed between sexes.

The IAAF regulations for athletes with DSDs state, “No stigmatisation or improper discrimination on grounds of sex or gender identity will be tolerated. In particular (but without limitation), persecution or campaigns against athletes simply on the basis that their appearance does not conform to gender stereotypes are unacceptable.”

Yet the issue with Semenya stems in part from views about gender and how women should look. When Semenya won the 800 meters at the 2009 World Championships, Russia’s Mariya Savinova (who would later be stripped of her 2012 Olympic gold medal for doping, giving the title to Semenya) suggested Semenya was a man, saying, “Just look at her.” When Semenya won gold at the 2016 Olympics, fifth-place finisher Joanna Jozwik commented about Semenya and the other two medalists, Francine Niyonsaba of Burundi and Margaret Wambui of Kenya, “These colleagues have a very high testosterone level, similar to a male’s, which is why they look how they look and run like they run.”

Even Bermon has been unable to stick to the science. In 2012, he presented his research on testosterone at the International Convention on Science, Education and Medicine in Sport. During that presentation, he displayed images of bodybuilder Kenneth “Flex” Wheeler and Francisco Goya’s La Maja Desnuda to demonstrate what he considered “normal male and female.”

Flex Wheeler and La Maja Desnuda

Such criticisms follow a pattern of judging female athletes by their bodies. In 2014, a Russian tennis official referred to Serena and Venus Williams as “the Williams brothers.” Former tennis star Martina Navratilova was described as having manly arms” in a 2008 column. WNBA star Brittney Griner, who is 6’8″ and can dunk, also admitted to being called “a man.”

Contrary to its own regulations, there is evidence that the IAAF targeted Semenya specifically because of her appearance, highlighted by complaints from other competitors. As further evidence of this targeting, The Victory Press pointed out that the events covered by the IAAF regulations do not include the hammer throw and pole vault, despite the fact that the IAAF’s own research found that female athletes with higher testosterone had a competitive advantage in these two events. Instead, the regulations cover the 1500-meter and one-mile races, two events not addressed in Bermon’s 2017 paper, and events that would be logical races for Semenya to attempt if she chose not to fight the regulations on her preferred 800-meter race.

Fair Play or Social Norms?

Bermon’s words and similar descriptions of other female athletes follow a common theme. They suggest the case against Semenya is less about fairness than about perceptions of how women should look and behave. Similar motivations inflame the debate around transgender rights. If we cannot identify women by their appearances, an opponent of Semenya might argue, what is to stop women who are really more like men from taking advantage of the system? What is to stop transgender women (women who were assigned male sex at birth) from entering women’s bathrooms and preying on unsuspecting women?* What is to stop male athletes from posing as females to gain an unfair advantage?

However, both fears seem unfounded. There is no evidence of men posing as transgender women to invade women’s restrooms. In fact, transgender women are far more likely to be victims of violence, with twenty-eight transgender Americans murdered last year.

To me, the idea of rampant Juwanna Mann incidents in sports seems equally overblown. I grew up playing baseball in an environment where boys who lacked arm strength or proper throwing technique were told derisively that they threw “like a girl.” I played high school and college sports where the epithet “pussy” was used to describe a lack of competitive toughness. I find it hard to believe a male athlete conditioned under such rhetoric would dream of posing as a woman in order to gain a competitive advantage.

Female athletes should denounce the practice of judging competitors by their physical appearances.

Defending Their Own

It is clear that spectators, fellow athletes and track officials have long evaluated Semenya by her physical appearance. It may be the case that some aspect of her physiology confers an unfair advantage over her female competitors. However, any determination of such an advantage should be based upon independent, peer-reviewed studies. Furthermore, Bermon’s previous comments about archetypical bodies for each sex cast a shadow on his scientific conclusions. At the very least, the IAAF and other female athletes (not to mention all competitors, fans and officials) should denounce the practice of judging competitors by their physical appearances and follow through on those declarations. If speculations based on narrow-minded beliefs about what women should look like can lead to regulations to exclude targeted athletes, I would hope that Semenya’s fellow competitors would come to her defense. Were I competing against Semenya, I would worry that any variation in my appearance might provoke questions about my successes.

If independent, peer-reviewed scientific research clearly indicates that female athletes with certain levels of testosterone have a significant advantage, we can have a discussion about moving to testosterone-based divisions or some other measure to allow the fairest possible competition for all athletes. But no matter what the research shows, any decisions to exclude athletes on the basis of appearance-based speculations should be cast aside.

*-Caster Semenya is not transgender. But the backlash she faces often seems to have similar motivations to discrimination against transgender women.