Modern scientists debate whether or not women with high testosterone levels should be excluded from female sports competitions. Source: Wikimedia Commons, Credit: Erik van Leeuwen
In a recent case at the “Supreme Court of Sport” in Switzerland, female Indian sprinter Dutee Chand challenged a policy that prevents women with naturally high testosterone levels from competing against other female athletes. The policy, enacted by the International Association of Athletics Federations (IAAF), prohibits women whose testosterone levels exceed 10 nanomoles per liter of blood from female sports competitions (1). According to the IAFF, testosterone acts as a natural performance enhancer, so women with high testosterone levels have unfair advantages over other women. Other sports policy-makers like the International Olympic Committee (IOC) have also turned to testosterone as the most reliable differentiator between male and female athletes. To support this decision, policy-makers cite scientific studies that demonstrate that on average men’s testosterone levels are about 10 times those of women and that the highest levels seen in women are still significantly less than the lowest levels seen in healthy men (1).
In their article Debating a testosterone “sex-gap” published in the online magazine Science, anthropologist Katrina Karkaziz and sociomedical scientist Rebecca Jordan-Young question the validity of testosterone as the primary differentiator between male and female athletes. To craft their argument, Karkazis and Jordan-Young examine the contradictory results of two studies: the GH-2000 study, conducted by the IOC and World Anti-Doping Agency on 446 men and 234 women across 15 highly varied Olympic events in 2000, and the Daegu study, conducted by IAAF researchers on 849 elite women athletes in track and field from the 2011 Daegu World Championships (1). The results from the GH-2000 study showed that 13.7% of female athletes had testosterone levels above the typical female range, and 4.7% were within the typical male range. The study also showed that 16.5% of male athletes had testosterone levels below the typical male range, with 1.8% falling in the female range (1). By contrast, the results of the 2011 Daegu study showed that only 1.5% of female athletes had testosterone levels above the typical female range, directly contradicting the GH-2000 study (1).
Karkazis and Jordan-Young claim that the main reason these studies arrived at starkly different conclusions is that the GH-2000 study included “intersex” women, while the Daegu study omitted them. Put simply, “intersex” women have some biological characteristics that could be classified as male and some characteristics that could be classified as female. According to Karkazis and Jordan-Young, the Daegu study omitted them because Daegu researchers deemed “intersex” women as having hormonal disorders that made them unfit to be included in reference ranges for female athletes. Claiming that the GH-2000 results are more convincing, the two authors argue that “intersex” women are not “unhealthy” and therefore should be included in measuring normal testosterone levels for female athletes. The authors maintain that if the Daegu study had included “intersex” women, both it and the GH-2000 study would have concluded that there is in fact an overlap in average testosterone ranges between male and female athletes. Thus, the authors conclude that testosterone blood level is a poor criterion for prohibiting female athletes from competition, claiming that women “who were raised as girls and classify themselves as female should not be excluded” (1).
While the authors believe that women should be able to participate based on how they identify themselves, some scientists are concerned that female athletes could take advantage of the subjective power to choose whether they are eligible or not. Other critics of the authors’ article claim that the GH-2000 study is severely flawed because it did not account for participants who were doping with testosterone, which would explain some of the abnormally high testosterone levels (2). One notable critic, Dr. Eric Vilian, a professor of human genetics at the University of California, Los Angeles and an adviser to the IOC for eligibility in sports, claims that “it does not matter whether there is some overlap [of T between men and women] or no overlap at all . . . What matters is, what is the best marker [to set men and women apart]” (2). Scientists like Dr. Vilian will continue to conduct studies on testosterone levels in both male and female athletes to resolve this issue in the most equitable way possible.
References:
- Karkazis, K. & Jordan-Young, R. (2015, May 22). Debating a testosterone “sex gap.” Retrieved May 21, 2015, from http://www.sciencemag.org/content/348/6237/858.full
- Geggel, Laura. (2015, May 21). Testosterone Rules for Women Athletes Are Unfair, Researchers Argue. Retrieved May 24, 2015, from http://www.livescience.com/50938-female-athletes-testosterone-olympics.html