Lia Thomas: Trans swimmer didn’t have unfair advantage, data shows

On 17 March, Lia Thomas became the first openly transgender athlete to win America’s top trophy in university sports when she swam to victory in the women’s 500 yard (457 meter) freestyle race.

Ms Thomas, 22, won first place in the National Collegiate Athletic Association’s (NCAA) first division swimming championship, her final competition as a college athlete.

Amid her success, though, Ms Thomas has become a lightning rod in the debate about trans women in sport, as well as a target for much of the American right.

Her right to compete in women’s races, and sometimes her gender itself, has been attacked by sports stars, politicians, activists, her competitors, and even some of her teammates’ parents, as well as protesters at the NCAA championship last week, who argued that her time living as a man gives her an unfair advantage.

Florida’s Republican governor Ron DeSantis, who last year approved legislation banning trans women from high school and college women’s sports, even signed a proclamation on Tuesday declaring 500-yard runner-up Emma Weyant the “rightful winner”.

Yet in all this, there has been scant detail about how Ms Thomas’s performance actually compares to other women at her level. The Independent crunched the numbers – and found little evidence that she poses any threat to women’s sport.

How hormone therapy transforms trans athletes’ bodies

Ms Thomas began swimming at the age of five, and came out to her family in summer 2018. She began to use her new name Lia Catherine Thomas, on new year’s day in 2020.

“In a way, it was sort of a rebirth,” she told Sports Illustrated in an interview this year. “For the first time in my life, feeling fully connected to my name and who I am and living who I am.”

It was May 2019 when she began gender-affirming hormone replacement therapy (HRT), which involves taking supplements of estrogen or testosterone to bring a trans person’s hormones in line with that of a cisgender (or non-transgender) person. This is usually the first step in what’s known as “medical” transition, as opposed to social transition (such as changing how you dress).

Men and women typically have naturally different hormone balances, although there is much variation within each sex. As we grow, those hormones cause our bodies to develop in different ways, which is why male athletes tend to perform at higher levels than female athletes.

However, our bodies still retain the capacity to respond to new hormones in adulthood, and so HRT causes radical changes to a person’s secondary sex characteristics.

For trans women, that means growing breasts, thinning body hair, changes to…