Getty Images

Lia Thomas, a transgender swimmer for the University of Pennsylvania, made history on Thursday. Thomas won the women's Division I national championship in the 500-yard freestyle, becoming the first known transgender athlete to win a Division I title.

Thomas finished in a blistering four minutes and 33.24 seconds good for 1.75 seconds ahead of Virginia's Emma Weyant, who came in second and just nine seconds behind Katie Ledecky's record of 4:24.06.

According to ESPN, there were not many cheers of support for Thomas during introductions before the race. The swimmer successfully tuned everyone out, though.

"It means the world to be here ... I try to ignore it as much as I can," Thomas said after race, ESPN reported. "I try to focus on my swimming, what I need to do to get ready for my races. And just try to block out everything else

Thomas did not participate in the postrace news conference required by the NCAA. As ESPN noted, more than 20 people representing Save Women's Sports and Young Women for America stood outside of where Thomas was competing to protest the swimmer competing in the women's category.

A third group, Concerned Women for America, on Thursday announced that they are filing a Title IX complaint against Penn for "violating Title IX by allowing Thomas to compete on the women's team," according to ESPN.

"The future of women's sports is at risk and the equal rights of female athletes are being infringed," CWA president and CEO Penny Nance said. "We filed a formal civil rights complaint against UPenn in response to this injustice."

The win is Thomas' first national championship, but it adds to four Ivy League championships.