Caster Semenya has lost a landmark case against athletics’ governing body meaning it will be allowed to restrict testosterone levels in female runners.
The Court of Arbitration for Sport (Cas) rejected the South African’s challenge against the IAAF’s new rules.
But Cas said it had “serious concerns as to the future practical application” of the new rules.
Semenya, 28, had said the regulations were “unfair” and that she wanted to “run naturally, the way I was born”.
Now she – and other athletes with differences of sexual development (DSD) – must either take medication in order to compete in events from 400m to the mile, or change events.
Cas found that the rules for athletes with DSD were discriminatory – but that the discrimination was “necessary, reasonable and proportionate” to protect “the integrity of female athletics”.
Cas has asked the IAAF to consider delaying the application of the rules to the 1500m and one-mile events until more evidence is available.
The new rules come into effect on 8 May.
The ruling means athletes who want to compete at September’s World Championships in Doha will have to start taking the medication within one week.