CAPE TOWN -Olympic 800-metres champion Caster Semenya on Wednesday lost her appeal against rules that mean middle distance female athletes with high natural levels of testosterone must take medication to reduce it. The Court of Arbitration for Sport (CAS) ruled the regulations were necessary for athletes with differences in sexual development (DSDs) to ensure fair competition.

But it also voiced concern about how the new rules, which cover events ranging from 400-metres to a mile, would be implemented by the International Association of Athletics Federations (IAAF), the sport’s governing body. Testosterone increases muscle mass, strength and haemoglobin, which affects endurance. Some competitors have said women with higher levels of the hormone have an unfair advantage.

 “I know that the IAAF’s regulations have always targeted me specifically,” Semenya, 28, said in a statement released via her lawyers. “For a decade the IAAF has tried to slow me down, but this has actually made me stronger. The decision of the CAS will not hold me back. I will once again rise above and continue to inspire young women and athletes in South Africa and around the world.”