South Africa’s Olympic athlete Caster Semenya on Wednesday said the decision by the Court of Arbitration to maintain IAAF rules forcing female athletes to regulate their testosterone levels will not hold her back.

“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,” she said in a statement released by her legal team.

Semenya, a double Olympic champion, was fighting measures imposed by the International Association of Athletics Federations (IAAF) that compel “hyperandrogenic” athletes – or those with “differences of sexual development” (DSD) – to lower their testosterone levels if they wish to compete as women.

A three-judge panel at the Court of Arbitration for Sport said even though the rules are “discriminatory...such discrimination is a necessary, reasonable and proportionate means of achieving the IAAF’s aim of preserving the integrity of female athletics in the Restricted Events.”

But the three judge-panel voiced “serious concerns” about the viability of rules moving forward.

The IAAF said it was “grateful” for the CAS ruling and that the rules – first adopted last year but suspended pending the legal battle – will come into affect on May 8.

“Sometimes it’s better to react with no reaction,” Semenya said on Twitter after the verdict was announced.