Lia Thomas , a transgender college athlete, is dominating US women's swimming.- New USA Swimming regulations, however, could make it more difficult for her to eventually turn pro.
The United States' governing body for competitive swimming has updated its policy on the eligibility of transgender athletes in elite events.
The changes come in the aftermath of collegiate swimmer Lia Thomas, who is transgender, breaking a number of US women's swimming records.
USA Swimming said on Tuesday that transgender athletes who have undergone or are undergoing a male-to-female transition must now remain below a testosterone threshold of five nanometers per liter for 36 months before competitions.
Previously, transgender women were allowed to compete in women's events if they had undergone a year of hormone-suppression therapy.
A three-person medical panel will also now be used to determine whether "prior physical development of the athlete as a male" gives transgender swimmers an unfair advantage.
USA Swimming said in a statement that the new policy, which is effective immediately, "acknowledges a competitive difference in the male and female categories and the disadvantages this presents in elite head-to-head competition."
It added that the policy aims to "mitigate the advantages associated with male puberty and physiology."
The organization cited data showing that the top-ranked female athlete would on average have ranked 536th in short course male events during 2021, and 326th in events longer than 50 meters.
"USA Swimming has and will continue to champion gender equity and the inclusivity of all cisgender and transgender women and their rights to participate in sport, while also fervently supporting competitive equity at elite levels of competition," it said.
The new regulations don't mention Lia Thomas by name, but their introduction comes as she makes headlines across the world for her record-breaking performances.
Thomas, 22, competed for the men's swimming team at the University of Pennsylvania for three years before switching to compete for the women's team in 2020 after transitioning.
She has since broken a number of national women's swimming records in the US, including the 200 meter and 500 meter freestyle records at the Zippy Invitational Event in Akron, Ohio in December.
In the 500 meter freestyle at the event in Akron, Thomas finished 14 seconds faster than the second placed swimmer.
It remains unclear how the new policy will affect Thomas if she moves into the world of professional swimming as expected, however for now, she is expected to be permitted to keep competing.
USA Swimming states the policy applies only to members of USA Swimming and specific contests that are considered "elite" events. Collegiate conference or national championships, however, are not listed as "elite" events by the organization.
"At the non-elite level, an inclusive process has been established by which an athlete can elect to change their competition category in order for them to experience the sport of swimming in a manner that is consistent with their gender identity and expression," said USA Swimming.
Thomas is scheduled to compete in the NCAA championship in Atlanta in March. USA Swimming told Sportsmail that the decision as to whether Thomas can compete in the event is a decision for the NCAA.
On Tuesday, Thomas' teammates at the University of Pennsylvania released a statement supporting her.
"As members of the Penn Women's Swimming and Diving team and teammates of Lia Thomas, we want to express our full support for Lia in her transition," the team members said a letter shared with ESPN.
Referring to a recent Fox News interview with an anonymous team member who said they disagreed with Thomas' inclusion on the women's team, the statement continued: "We value her as a person, teammate, and friend. The sentiments put forward by an anonymous member of our team are not representative of the feelings, values, and opinions of the entire Penn team, composed of 39 women with diverse backgrounds."
The statement was not signed, but a Penn spokesperson told ESPN said that it represented "several" members of the team.