New research has been published in the British Journal of Sports Medicine

A landmark study has shown the most conclusive evidence yet that female athletes with high levels of naturally occurring testosterone receive significant performance-enhancing benefits.

The study, which was commissioned by the International Association of Athletics Federations (IAAF), measured blood testosterone levels in female athletes in 21 events at the 2011 and 2013 World Championships.

“Among other things, the study found that in certain events female athletes with high testosterone levels benefit from a 1.8% to 4.5% competitive advantage over female athletes with lower testosterone levels,” read an IAAF release in part.

The IAAF’s hyperandrogenism regulations will remain unchanged for next month’s IAAF World Championships but the news comes a few weeks before the world governing body is set to challenge a ruling by the Court of Arbitration for Sport (CAS) which, since 2015, has prevented it from restricting permitted levels of testosterone among female competitors.

Dr Stéphane Bermon, who has been a member of the IAAF and IOC working groups on hyperandrogenic female athletes and transgender athletes, jointly headed the study with Dr Pierre-Yves Garnier, director of the IAAF health and science department.

Dr Bermon said: “Our starting position is to defend, protect and promote fair female competition. If, as the study shows, in certain events female athletes with higher testosterone levels can have a competitive advantage of between 1.8-4.5% over female athletes with lower testosterone levels, imagine the magnitude of the advantage for female athletes with testosterone levels in the normal male range.

“This study is one part of the evidence the IAAF will be submitting to CAS regarding the degree of performance advantage that hyperandrogenic female athletes enjoy over female athletes with normal testosterone levels. We continue to gather more data and research on our journey to providing a fair and level playing field for females in our sport.”

Female athletes with hyperandrogenism – a medical condition characterised by excessive levels of male sex hormones such as testosterone – has been one of the most controversial and emotive topics in athletics in recent years.