Double Olympic 800m champion Caster Semenya has lost her appeal to the Swiss Federal Tribunal, to set aside a 2019 Court of Arbitration (CAS) ruling that female athletes with a high natural level of testosterone must take medication to reduce it.
South Africa's Semenya approached the tribunal in May last year, after CAS - sport's highest court - ruled that World Athletics regulations were necessary for athletes with differences in sexual development (DSDs) to ensure fair competition in races ranging from 400m to a mile.
The tribunal found the requirement of subjecting certain female athletes to drug or surgical interventions as a precondition to compete does not amount to a violation of Swiss public policy, Semenya's lawyer says.
Testosterone increases muscle mass, strength and hemoglobin, which affects endurance. Some competitors claim women with higher levels of the hormone have an unfair advantage.
"I am very disappointed by this ruling, but refuse to let World Athletics drug me or stop me from being who I am," Semenya says.
"Excluding female athletes or endangering our health solely because of our natural abilities puts World Athletics on the wrong side of history.
"I will continue to fight for the human rights of female athletes, both on the track and off the track, until we can all run free the way we were born.
"I know what is right and will do all I can to protect basic human rights for young girls everywhere."
Semenya has already indicated she will focus on the shorter 200m sprint event, which falls outside of the regulations, at the Tokyo Olympic Games that were postponed to next year, due to the COVID-19 pandemic.