Caster Semenya, the Olympic 800m champion, may be banned from competing at future Games unless she undergoes hormone replacement therapy (HRT) or even surgery in the wake of a landmark study into athletes with raised testosterone levels which has just been published.

The International Association of Athletics Federations, the world governing body, commissioned research which has produced the most conclusive evidence yet that female athletes with very high levels of naturally occurring testosterone receive significant performance-enhancing benefits in competition.

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It comes only weeks before the IAAF is set to challenge a ruling by the court of arbitration for sport which, since 2015, has prevented it from restricting permitted levels of testosterone among female competitors.

The new study will not stop Semenya and other hyperandrogenic athletes, such as the Indian sprinter Dutee Chand, from competing at the world championships in London in August but it could have a significant impact on the Cas hearing later this month.

It is bound to reopen the controversial and emotionally charged debate around the treatment of female athletes with hyperandrogenism, a medical condition characterised by excessive levels of male sex hormones such as testosterone.

Researchers measured blood testosterone levels in 1,332 female athletes competing across 21 track and field disciplines at the 2011 and 2013 world championships. Those with the highest levels of testosterone demonstrated significant advantages over those with the lowest levels – notably in the 400m (2.7% faster), the 400m hurdles (2.8% faster), the 800m (1.8% faster), the hammer throw (4.5% longer) and in the pole vault (2.9% higher).

Although these margins appear small, at the highest level a performance boost of a few percentage points might mean the difference between winning gold and missing out on a medal.

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Stéphane Bermon led the research from the Monaco Institute of Sports Medicine and Surgery, together with Dr Pierre-Yves Garnier, director of the IAAF health and science department. Bermon said: “This study brings new evidence [of] the performance-enhancing effects of androgens in elite female athletes. Although long suspected [to be the case], until now there was no proof.

“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 and 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.”

Among female athletes testosterone is the most widely abused performance-enhancing drug, Bermon said. Of the 116 female athletes serving a doping ban as of December 2016, 64 had tested positive for androgens.

Chand, a 100m and 200m sprinter, successfully challenged IAAF regulations restricting permitted testosterone levels in 2015. These regulations mandated that affected individuals had to receive hormone treatment to lower their testosterone levels artificially if they wanted to compete in the female category of competition. Cas ruled the IAAF regulations must be suspended until evidence of the impact of circulating androgens, like testosterone, on sporting performance could be produced.

This missing evidence prompted the current study, published in the British Journal of Sports Medicine.

Facebook Twitter Pinterest Indian athlete Dutee Chand. Photograph: Aijaz Rahi/AP

Testosterone has several potential performance-enhancing effects on the body, including boosting the oxygen-carrying capacity of the blood, building lean muscle mass and increasing mental drive and aggressiveness. The new study also found that female competitors with high levels of androgens benefit from improved visuospatial abilities.

Bermon believes the study’s findings have significant implications for future rulings on testosterone in elite women’s sport. “We believe that these results could help the CAS jury to better understand the relationship between androgen levels and athletic performance. Additionally, our work addresses the main CAS request: quantification of the advantage experienced by female athletes with very high level of circulating androgens when compared to athletes with normal level of androgens.”

The IAAF has commissioned a second piece of research and sources told the Guardian it would look at the effect naturally occurring testosterone has on 100m and 200m sprinters like Chand, as well as middle distance runners and throwers.