(CNN)Burundian runner Francine Niyonsaba, who has an intersex condition, broke a world record on Tuesday.
The 28-year-old set a new 2,000m record at a Continental Tour Gold meeting in Zagreb, Croatia, breaking the previous record by more than two seconds. Niyonsaba finished with a time of 5:21.26, surpassing Genzebe Dibaba's 2017 record.
Niyonsaba, a 2016 Rio Olympic Games silver medalist in the 800m, is one of the athletes banned by World Athletics from competing in women's races from 400m to one mile in distance because of what they consider to be her body's elevated levels of naturally occurring testosterone, her sensitivity to the hormone, and her unwillingness to submit to medical interventions to alter those characteristics.
Niyonsaba has hyperandrogenism, a condition characterized by the natural production of more testosterone than women without the condition.
In order to compete, those athletes must lower their testosterone levels with medication or surgery, which World Athletics says is intended to "ensure fair competition."
In 2019, the Court of Arbitration for Sport (CAS) upheld World Athletics' DSD rules when they were challenged by South African runner Caster Semenya. She lost a subsequent appeal and in February took her case to the European Court of Human Rights. That case is still pending.
Niyonsaba said in 2019 that requiring medical interventions of certain women in order to compete was a form of "discrimination."
"It doesn't make sense. For sure, I didn't choose to be born like this. I love running, and I will not stop running."
Niyonsaba has had an excellent 2021 so far, winning the 5,000m Wanda Diamond League title, as well as finishing fifth in the 10,000m at the 2020 Tokyo Olympics.
And in the 2,000m event -- a distance not run at the Olympics or the World Championships -- in Zagreb, continued her excellent form, dominating the race.
Finishing four seconds ahead of second-placed Freweyni Hailu with a final lap of 63 seconds, Niyonsaba became the new world record holder in the distance.
"I am feeling seriously wonderful. I didn't realize I could run a world record, but it was my first time here. I came here to do what I have to do," she said afterwards
"I did it. It's wonderful and it's fabulous. The pacing was really perfect. I want to thank all the people who came to cheer us."