Olympic champion Caster Semenya has lodged a legal appeal against new rules restricting testosterone levels in female athletes.

The 800-metre runner filed her case in Switzerland’s Federal Supreme Court, publicly declaring “I am a woman and I am a world-class athlete”.

“The IAAF (International Association of Athletics Federations) will not drug me or stop me from being who I am.”

The testosterone regulations which came into effect on May 8 require middle-distance female runners with a high natural level of testosterone to medically lower them to be eligible to compete in events ranging from 400 meters to the mile.

A week earlier, on May 1, the Court of Arbitration for Sport (CAS) rejected the 28-year-old South African’s challenge against the IAAF’s new regulations.

It ultimately ruled them necessary for athletes with differences in sexual development (DSDs) to ensure fair competition. 

Champion 800m runner Caster Semenya is determined to compete with her naturally high levels of testosterone. Photo: AAP

Ms Semenya will ask the Swiss Federal Supreme Court to set aside CAS’s decision in its entirety, which it said did not consider medical protocols and uncertain health consequences of taking testosterone-reducing medication.

Under the new regulations, female athletes with high natural levels of testosterone wishing to compete in events from 400m to a mile must medically limit that level to under five nmol/L, double the normal female range of below two nmol/L.

Ms Semenya has repeatedly stated she will not take medication to comply with the regulations, which came into effect on May 8, but she has also vowed to continue to compete in the 800m.

Testosterone is a hormone that increases muscle mass, strength and hemoglobin – which affects endurance.

Ms Semenya won her last competitive 800m race at a Diamond League meeting in Doha on May 3 and has pledged to return to Qatar to defend her world title in September, but the regulations will not allow her to compete unless she takes medication.

Ms Semenya, who also races 5,000 metres, could continue to compete in longer distances not affected by the rule change but she has vowed to continue her fight to stay competing in the 800 metres, which she recently said was her calling.

-with AAP