Female runners with high testosterone must reduce those levels or will not be allowed in international races between 400m and the mile, according to an IAAF rule starting Nov. 1.
Olympic 800m champion Caster Semenya, who was gender tested in 2009, is expected to be affected, according to South Africa’s Olympic Committee.
“Our evidence and data show that testosterone, either naturally produced or artificially inserted into the body, provides significant performance advantages in female athletes,” IAAF president Seb Coe said in a press release. “The revised rules are not about cheating, no athlete with a DSD [difference of sexual development] has cheated, they are about leveling the playing field to ensure fair and meaningful competition.