Olympic champion Caster Semenya and others with hyperandrogenism could be forced in to hormone therapy if they want to compete in future Games. A study found that females with high testosterone levels have an advantage.
In findings that are sure to re-ignite the debate on the sporting participation of athletes whose gender has been questioned, the study, commissioned by atheltics' governing body the IAAF, found that the condition offers a "significant competitive advantage."
Hyperandrogenism causes high natural levels of the male hormone, testosterone, in women.
The IAAF will use the study in its appeal to the Court of Arbitration for Sport (CAS), which suspended an IAAF rule that enforced a limit on female athletes' naturally occurring testosterone levels. Despite this, South African middle distance runner Semenya and Indian sprinter Dutee Chand, who also has hyperandrogenism, are likely to be able to compete in year's world championships, where Semenya is expected to win her third 800m title to add to her Olympics golds from 2012 and 2016.
The study, funded by IAAF and the World Anti-Doping Agency, was published in the British Journal of Sports Medicine. It took into account more than 2,100 androgen samples from athletes who took part in the 2011 and 2013 world championships.
It found females with higher testosterone levels received a competitive advantage of 1.8 percent to 4.5 percent over female athletes with lower testosterone levels in 400 and 800-meter races, hammer throw and pole vault.
"If, as the study shows, in certain events female athletes with higher testosterone levels can have a competitive advantage of between 1.8 to 4.5 percent over female athletes with lower testosterone levels, imagine the magnitude of the advantage for female athletes with testosterone levels in the normal male range," said one of the study's authors, Stephane Bermon.
Among female athletes testosterone is the most widely abused performance-enhancing drug, Bermon added. Should the appeal to CAS be successful, it's likely that those in Semenya's position would have to bring testosterone levels down before competing in the Olympics.