Lia Thomas has made a splash in US collegiate women's swimming with her dominant performances for the University of Pennsylvania. But just a few years ago, she competed on the men's team. The 22-year-old's runaway success in the pool this season has reignited debate about inclusivity in sports and the competition requirements for transgender athletes. Thomas' case has already prompted the National Collegiate Athletic Association (NCAA) to amend its policies, and USA Swimming, which governs the sport at the elite level, is considering changes as well.
The debate has been complicated by an avalanche of right-wing outrage.
"Did you see the swimmer that's breaking records, like by 30 seconds?" former president Donald Trump said at a political rally in Arizona this month.
"We will ban men from participating in women's sports," he said, without naming Thomas, who joined UPenn's women's swim team in September 2021.
'Overperforming' or simply better?
In one of only a few interviews given since the controversy ignited, Thomas said she realized she was transgender in the summer of 2018, but initially still wanted to compete on the men's team because of the uncertainty that awaited her with her transition.
"I didn't know what I would be able to do or (if I would) be able to keep swimming," she told SwimSwam magazine's podcast.
"That caused a lot of distress to me. I was struggling. (...) I wasn't able to focus on swimming or school or friendships as much as I wanted to."
Thomas said she began her transition in May 2019 with hormone replacement therapy -- a combination of estrogen and testosterone suppressants.
In her first season on the women's swim team, she is putting her opponents on notice.
In early December at a meet in Ohio, she notched the best times of the year in the 200m and 500m freestyle. Last weekend at a meet against Harvard, she won the 100m and 200m freestyle.
The NCAA already required transgender women to take testosterone suppressants for a year before becoming eligible to compete on women's teams, which Thomas did.
But now, transgender women are expected to be asked to meet certain testosterone thresholds set for each sport.
At issue is how testosterone, which helps young men develop muscle mass through puberty, affects athletic performance. Some say because Thomas went through puberty before transitioning, her muscular build gives her an unfair advantage.
"Lia is overperforming in women's events," the Women's Sports Policy Working Group -- an advocacy organization made up of former elite athletes and sports administrators -- said in a letter to the NCAA.
The group said while all transgender women including Thomas should be allowed to compete head-to-head in women's events, they should demonstrate that they have "rolled back the sport advantages that result from male puberty."
The group -- which counts US Olympic gold medal swimmers Nancy Hogshead-Makar and Donna De Varona as members -- cited a preliminary study showing that Thomas's results are "too close to her pre-transition bests in men's events."
Discrimination
But Thomas's backers say such analysis is not scientifically sound and only serves to perpetuate discrimination suffered by transgender athletes.
"Thomas is simply an athlete who loves her sport, trains hard, and followed all requirements to participate in swimming; Still, she has been the focus of violent and abusive rhetoric," advocacy group Athlete Ally said after the NCAA rule changes.
Several conservative-led US states, including Texas and Florida, have adopted laws barring transgender girls from competing in high school sports.
Weightlifter Laurel Hubbard made Olympic history at the Tokyo Games last year as the first transgender woman to compete, but the debate over inclusion rages on.
In November, the International Olympic Committee sent the ball back into the courts of each sport's governing body, saying there was "no scientific consensus on how testosterone affects performance across all sports."
And now the NCAA is planning to adopt a similar approach.
World Athletics updated their rules on transgender athletes in 2019, which is why transgender hurdler CeCe Telfer was deemed ineligible last year to vie for a spot on the US Olympic team for Tokyo.
For its part, the University of Pennsylvania has voiced support for Thomas, in the run-up to the NCAA championships in March.
If Thomas qualifies, she could find herself competing against Izzi Henig, a transgender man who swims for Yale but decided not to begin hormone replacement therapy in order to remain on the women's team.
Earlier this month, in a head-to-head battle, Henig defeated Thomas.