IOC released new rules for transgender athletes at the LA28 Olympic Games (Photo by Kevin Mazur/Getty Images for LA28)
Kevin Mazur/Getty Images for LA28
The rules for who qualifies to compete as a female athlete in the Olympics have changed—again. But this time, the International Olympic Committee (IOC) is replacing years of shifting, sport-by-sport standards with a single test. As a result, all transgender women will be banned from competing in female events at LA28.
The SRY Gene Test
The IOC announced the new policy today, and it will apply to athletes in the LA28 Olympic Games. “Eligibility for the female category is to be determined in the first instance by SRY gene screening to detect the absence or presence of the SRY gene,” the IOC reported. An athlete will only need to complete one test to determine lifetime eligibility.
SRY (short for Sex-determining Region Y) is a gene found on the Y chromosome that plays a key role in biological sex development and triggers the formation of testes. The testes then produce hormones, like testosterone, that guide the body to develop male biological characteristics. If the SRY gene is absent, as in most biological females with XX chromosomes, the body typically develops ovaries and female biological characteristics.
The cheek swab or blood test that the IOC will require for female athletes will determine the presence or absence of SRY. Only those without the SRY gene will be able to compete as women in Olympic events.
The new rule doesn’t just eliminate transgender women from eligibility, but also women with certain conditions known as differences in sexual development. Some of these individuals who were identified as female at birth may still carry the SRY gene. While they may have been raised as girls and identify as female, they likely have high testosterone levels. The presence of the SRY gene means they would not be eligible to compete in the Olympic female categories under the new rules.
The new rule only applies to athletes who want to compete in Olympic events.
Exceptions To The New Rule
There are a few exceptions to this policy. Although rare, some individuals with the SRY gene have conditions, such as Complete Androgen Insensitivity Syndrome (CAIS), in which their bodies do not respond to testosterone and therefore do not gain its performance advantages. In these cases, athletes may still be eligible to compete in female Olympic events.
The Male Advantage In Sports
The IOC says that biological males have an advantage in sport, and so the new rule was needed to protect competition in the female division. They claim there is a 10-12% male performance advantage in most running and swimming events, and a more than 20% performance advantage in most throwing and jumping events. And they claim the male advantage can be greater than 100% in events that involve explosive power, like in collision, lifting and punching sports.
The IOC attributes this advantage to men’s greater testosterone. They explain that men experience three significant testosterone peaks: in utero, in infancy and beginning in puberty through adulthood. This gives biological males “larger and stronger skeletal muscle and bone, larger and stronger hearts, larger lung size, more red blood cells, and lower body fat than females,” the IOC explains in their report. This gives men a large advantage in sports, especially those that rely on strength, power or endurance.
How We Got Here: The Changing Rules Of Eligibility
Eligibility rules for female athletes in past Olympics were convoluted and varied from sport to sport and even from event to event within sports. Here’s how we got to the current rule.
In 2015, the IOC allowed transgender women to compete in female events if their testosterone levels remained below 10 nanomoles per liter for at least 12 months prior to competition. In 2019, World Athletics tightened that standard, lowering the limit to 5 nanomoles per liter. Most cisgender female athletes have testosterone levels significantly lower than that threshold, between 0.12 and 1.79 nanomoles per liter.
At this time, some elite athletes were taking birth control pills to lower their testosterone levels so they could compete in female events. Caster Semenya, an elite runner with high testosterone, challenged World Athletics’ testosterone rules in court, saying she tried taking birth control pills to control her testosterone but felt they made her more injury-prone. The court ruled against her in 2019.
In the 2021 Olympics, Laurel Hubbard, a transgender weightlifter from New Zealand, was permitted to compete as a female because her testosterone levels met the requirements. Hubbard became the first transgender athlete to compete at the games.
In addition to the rules impacting transgender athletes, World Athletics ruled that women who were assigned female at birth but had naturally high testosterone also needed to meet the five nanomoles per liter testosterone requirement in order to compete as women in the 400, 800, and one-mile women’s races. In 2021, two runners were banned from the 400-meter race due to naturally high testosterone levels but were allowed to compete in the 200-meter event. In other words, the pair qualified as female for shorter distances but not for distances between 400 meters and a mile.
After the Tokyo Olympics, in November 2021, the International Olympic Committee instituted yet another set of guidelines for transgender athletes, which gave each sport’s international federation the final call on who could compete in female categories.
Many sports, including track and field, weightlifting, swimming and cycling, instituted new rules that barred transgender women who went through puberty as males.
Other sports required female athletes to maintain testosterone levels below a specific threshold to compete in the female divisions, but the threshold varied from sport to sport. In tennis, transgender women were required to have less than five nanomoles per liter for at least the previous 12 months. For archery and the triathlon, the cutoff was 2.5 nanomoles per liter for 24 months. Still, other sports, like World Rugby and the World Boxing Council, banned transgender women completely.
Now, the IOC is shifting away from this patchwork of policies toward a single standard. The new rule released today applies to all female athletes in all Olympic sports. The IOC says it surveyed and interviewed athletes from around the world, and “the athlete consultation revealed a strong consensus that fairness and safety in the female category requires clear, science-based eligibility rules.”
Support For Female Transgender Athletes Has Waned
The new rule comes at time when support for transgender athletes is waning. A 2025 Gallup poll found that just 24% of Americans support allowing athletes to compete on teams that align with their gender identity. When Gallup first asked this question in 2021, support stood at 34%, 10% higher than the most recent poll. These polls measured attitudes toward athletes in general, and not Olympians. Despite waning support for transgender athletes, the topic remains controversial.
More Clarity, But Not Consensus
After years of inconsistent rules regarding who qualifies as a female athlete, the IOC has drawn a much clearer boundary. Whether that clarity leads to consensus or simply to a new phase of controversy remains to be seen.
