World athletics' governing body today introduced controversial new rules for female athletes who have high testosterone levels in a move seen as targeting South Africa's double Olympic 800 metres champion Caster Semenya.
The new rules will allow such athletes to compete only if they take medication to reduce naturally occurring levels of testosterone.
Semenya has long raised controversy because of her powerful physique and deep voice related to hyperandrogenism, the medical condition which causes a person to produce high levels of male sex hormones.
She replied to the new rules, which come into effect on November 1, 2018, by retweeting messages of support and the slogan: "How beautiful it is to stay silent when someone expects you to be enraged."
Dr Stephane Bermon, of the IAAF Medical and Science Department, said in a statement: "The latest research we have undertaken, and data we have compiled, show that there is a performance advantage in female athletes with DSD over the track distances covered by this rule."
IAAF President Sebastian Coe said: "The revised rules are not about cheating -- no athlete with a DSD has cheated -- they are about levelling the playing field to ensure fair and meaningful competition in the sport of athletics."