Feature articles

Regression, Not Progress: A Response to World Athletics’ Return to Sex Testing

April 3, 2025

Lindsay Parks Pieper¹, Jaime Schultz² & Jörg Krieger³
¹ University of Lynchburg; ² Pennsylvania State University;
³ Aarhus University & University of Inland Norway

World Athletics (WA) recently announced that it will reinstitute mandatory sex testing in women’s track and field. Specifically, the federation will require competitors to submit to a cheek swab or dry blood spot analysis for genetic testing to verify their sex. “Neither of these are invasive and they will be done to absolute medical standards,” explained WA President Sebastian Coe. “We will doggedly protect the female category and do whatever is necessary to do it.”

Although an official policy remains forthcoming, WA suggested it will use the presence of the SRY gene as a “highly accurate proxy for biological sex.” The SRY gene is typically located on the Y chromosome and can trigger the development of testes. The typical cisgender man’s sex chromosomes are XY; the typical cisgender woman’s sex chromosomes are XX, although many variations can occur, some of which lead to differences of sex development (DSD). WA’s test will likely be used to disqualify transgender women and women with DSDs, even though there is no definitive link between the SRY gene and athletic talent.

Coe might be convinced of the test’s utility, but he ignores a long, troubling history. Sex-testing policies have repeatedly proven flawed, reinforce negative gender norms, and cause irreparable harm to athletes. Over the last century, WA has tried to verify the sex of women athletes using physical exams, chromosome checks, DNA tests, and testosterone thresholds. Each version of sex testing ultimately collapsed under scientific and ethical scrutiny. But rather than learn from its past mistakes, WA’s new policy repeats them.

Like the tests, Coe’s assertion that women’s sport needs protection is not new. From the beginning, male sport leaders expressed suspicions about female athletes who ran too fast or jumped too far. Starting in the 1930s, WA (then the IAAF until a name change in 2019) required all women to produce physician-endorsed medical certificates affirming their sex. Concerned that some countries would submit fraudulent documentation, the WA enacted sport’s first on-site, compulsory tests in 1966. The invasive, humiliating tests took two forms: a “nude parade” for visual inspections and a gynecological exam.

The degrading examinations, coupled with contemporary scientific advancements, convinced the federation to turn to the Barr body test, which looked for the XX sex chromatin pair through a buccal smear (cheek swab). Medical practitioners immediately warned against this method. Even geneticist and anatomist Murray Barr, of the eponymous Barr body, requested sport officials stop using the technique. “Buccal smear testing in the area of athletics is totally inappropriate,” he wrote. “Its use in this way has been an embarrassment to me.”

The inaugural use of the Barr body test confirmed critics’ concerns when Ewa Kłobukowska, who had passed an earlier visual inspection, “failed” the mandatory check. The six men who investigated her case at the 1967 European Cup determined that the Polish sprinter had “one chromosome too many”– likely chromosomal mosaicism, a DSD where a person has both XX and XY chromosomes. WA barred her from sport, erased her records, and callously disclosed her previously unknown condition to the public. As Polish Olympic Committee President Włodzimierz Reczek admonished, the ordeal “fills one with indignation because it disaccords with elementary ethics.” Even so, the WA, the IOC, and other organizations quickly adopted the same test.

After Kłobukowska’s humiliation, officials pledged to keep the test results confidential, making it difficult to know how many women have been disqualified. IOC Medical Commission member Eduardo Hay reported that at least one to two women faced expulsion from almost every Olympic Games. Experts estimate the tests could have excluded one out of every four hundred women. Regardless of the exact number, what remains clear is that the Barr body test was “one of the most horrid misuses of a scientific method,” as geneticists censured in 1970.

In just one example of misuse, Spanish hurdler María José Martínez Patiño was determined to have XY chromosomes in 1985, causing what she described as “incredible shame and violation.” As she fought her disqualification, she learned she has androgen insensitivity syndrome (AIS), a DSD in which a person is resistant to androgens and develops as female. Like Patiño, most individuals with AIS are assigned female at birth and raised as women. In other words, a Y chromosome does not always signify maleness.

Outcry from the scientific community finally convinced WA to discontinue on-site sex testing in 1992. The IOC abandoned the Barr body test and instead looked for the SRY gene. At the time, geneticists warned that they had “serious reservations” about the test and that “sex/gender did not equate with the presence or absence of Y chromosomal material.” It is therefore confounding that the WA will return to this same test in 2025, precisely because it failed its original use.

At the 1992 Barcelona Games, twelve athletes exhibited the SRY gene. Upon further analysis, however, experts determined that one sample was a false positive, six samples identified the wrong gene, and five samples were from athletes with DSDs. Four years later, at the centennial Olympic Games in Atlanta, the tests inaccurately identified eight women, who were all eventually cleared to compete. The faulty tests and resultant harms caused to athletes finally pushed the IOC to terminate the practice in 1999. “It took a long battle to put an end to gender testing,” wrote WA Vice President Arne Ljungqvist in his autobiography.“Gender testing was a flagrant abuse, nothing else.”

Still, the battle wages on. For the next twenty-five years, the WA adopted a policy of “suspicion-based testing” by forcing women of “questionable sex” to submit to invasive, demeaning analyses and dangerous, unnecessary treatments to compete as women. Most recently, the WA measured women’s testosterone levels, which the World Medical Association has called “contrary to medical ethics.” Even the IOC has advised against policies that require “invasive physical examinations” and that athletes “undergo medically unnecessary procedures of treatment” for eligibility.

The WA’s return to genetic testing revives one of sport’s most damaging regulations. The SRY test erroneously assumes that a single gene can definitively identify sex. Yet, science has never supported that claim. Women with DSDs may carry the gene but develop as females, just as some men may lack it but develop as males.

Coe is wrong when he suggests that sex testing protects women’s sport. The reintroduction of these tests does not mark scientific progress, but institutional regression. Sex testing has not, and will not, preserve fairness. Instead, it has caused and will cause irreparable harm to countless women.