New York (AFP) – A transgender American swimmer's controversial career hung in the balance Wednesday after USA Swimming announced new rules, including testosterone limits, that could impact her ability to race competitively.

Lia Thomas has dominated US collegiate women's swimming as a student athlete at the University of Pennsylvania where, just a few years ago, she competed on the men's team.

Now, amid an uproar fueled by those who say Thomas has an unfair advantage, USA Swimming unveiled guidelines that do not mention the 22-year-old by name but will impact her future in the sport — although exactly how remains unclear.

The policy said that because swimming is “an important vehicle for positive physical and mental health,” it remains committed to “greater inclusivity” at the non-elite levels of the sport.

But critics said the new policy from the governing body for competitive swimming in the United States might achieve just the opposite.

USA Swimming said it had created a new set of guidelines for transgender athlete participation in elite competition that “relies on science and medical evidence-based methods to provide a level-playing field for elite cisgender women, and to mitigate the advantages associated with male puberty and physiology.”

It said that a three-member panel comprised of medical experts and a veteran athlete was being established to implement the new policy and to rule on specific cases.

A key criterion that the panel will look for is that “from a medical perspective, the prior physical development of the athlete as a male, as mitigated by any medical intervention, does not give the athlete a competitive advantage over the athlete's cisgender female competitors.”

In addition, a swimmer is ineligible “unless the athlete demonstrates that the concentration of testosterone in the athlete's serum has been less than 5 nmol/L (as measured by liquid chromatography coupled with mass spectrometry) continuously for a period of at least 36 months before the date of application.”

Doctors measure testosterone in nanomoles per liter (nmol/L). According to New York's Mount Sinai hospital, the healthy range of testosterone in a woman is 0.5 to 2.4 nmol/L.

Thomas followed National Collegiate Athletic Association (NCAA) rules, undergoing a year-long testosterone suppression treatment. 

But some organizations, such as the Women's Sports Policy Working Group, have deemed these rules insufficient, especially in cases where an athlete has begun her transition after puberty.

Athlete Ally, an activist organization that combats homophobia and transphobia in sport, swiftly responded that the new USA Swimming policy appears to be targeting Thomas.

“These sweeping new restrictions appear to be a direct retaliation against Lia Thomas, a talented, hard-working athlete who has followed all guidelines, is supported by her team, and trains diligently,” said Anne Lieberman, the group's director of policy and programs.

‘Full support'

The NCAA, which governs US college sports, said in January it would enforce rules set forth by USA Swimming, which has the authority to bar swimmers from competitions.

A swim meet for the Ivy League — a grouping of top private northeastern US universities — is scheduled for February, and the NCAA National Championships are in March.

“Penn Athletics has been informed of the new USA Swimming transgender participation policy,” the university's sports department said in a statement. 

“We continue to work with the NCAA regarding Lia Thomas' participation in the 2022 NCAA Swimming and Diving Championship.”

Thomas said she began her transition in May 2019 with hormone replacement therapy — a combination of estrogen and testosterone suppressants.

In early December at a meet in Ohio, she notched the best times of the year at the university level in the 200m and 500m freestyle.

Her performances have renewed a long-running debate about the fairness of a transgender woman competing against those who were born biologically female.

Members of the Penn swimming team and diving team issued a statement supporting their transgender teammate.

“We want to express our full support for Lia in her transition,” they said in the statement released late Tuesday, apparently after one teammate spoke out about Thomas.

“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.”