With an atypical biological make-up, rivals question the right of Caster Semenya to race in women's events © Reuters

On Saturday night Caster Semenya will race in the final of the women’s 800 metres at the Olympic stadium in Rio de Janeiro. The South African is favourite to win gold.

A Semenya victory would be celebrated by her supporters as the culmination of years of hard work. But it would be denounced by detractors as one the most notorious in the history of the games.

Semenya is an “intersex” athlete, a woman born with higher amounts of testosterone and with a biological make-up that does not conform to typical classifications of male or female. Rival athletes argue she has an unfair advantage and question her right to race.

Meanwhile, the runner has been subjected to degrading gender tests and humiliating media speculation. As a result, Semenya has become the unwitting face of a debate over notions of gender in the 21st century.

While these arguments swirl, Semenya is focused on one thing: winning her first Olympic title. “Times don’t matter but medals matter,” she told reporters this week. “I just want to run my own race and so far it’s been very good.”

On Wednesday she easily won her semi-final in a time of 1:58:15 but declined to take questions afterwards.

A gold would be the climax of a difficult career. In 2011 the International Association of Athletics Federations (IAAF) responded to her emergence as one of the world’s best 800m runners by implementing a “hyperandrogenism” policy — asking athletes such as Semenya to take drugs to lessen their testosterone levels to limit their perceived advantage.

It was a jarring position to take. While suspicions rage over athletes surreptitiously taking performance-enhancing substances, Semenya and other intersex sportspeople were being forced to take drugs that limit their natural condition. The South African’s form slipped following the introduction of the rules, a drop in performance seen by opponents as vindication of the IAAF’s regulations.

Last year the policy was suspended by the Court of Arbitration for Sport, the global arbiter in sporting disputes, finding it was unclear whether intersex athletes have a significant biological advantage. Ever since, Semenya’s fast times have returned. She has run about a second faster than rivals this season.

Speaking to the Financial Times in Rio, Sebastian Coe, IAAF president, said it planned to provide the court with new evidence that would allow it to reinstate the policy.

“Where to the best of our ability that we can, we have to create . . . a level playing field,” he said, but added. “Let me make one other point really clear: she is absolutely entitled to be here. We should not be in the business of demonising athletes. [Semenya] is a daughter, she is a sister.

“We have a moral, but also a contractual, obligation to do this sensitively.”

The IAAF’s hyperandrogenism policy was triggered by Semenya’s emergence at the world junior championships in 2009, where she blasted past the pack to win the title. Some athletes complained about her appearance, believing she looked too masculine to be a woman.

When Semenya beat Russia’s Mariya Savinova in the world championships later that year, the beaten runner was asked about the South African’s gender. “Just look at her,” she was reported to have said.

After the victory Semenya was given a gender test, and the leaked results created a media firestorm. South African authorities were furious at their athlete’s treatment, filing a human rights complaint with the UN saying she was the victim of sexism and racism by the IAAF. Semenya released a statement in 2010 saying she had been “subjected to unwarranted and invasive scrutiny of the most intimate and private details of my being”.

In 2011 the IAAF ended so-called sex tests, instead opting for a test for hyperandrogenism. Intersex women who had a testosterone level “within the male range” were to be stopped from competing, unless they took measures such as taking drugs that suppress the naturally occurring hormone.

After the hyperandrogenism policy was implemented, Savinova beat Semenya to the 800m gold at the London 2012 Olympics. This year the World Anti-Doping Agency recommended a lifetime ban for the Russian in relation to revelations about the country’s state-sponsored doping regime.

Last year Dutee Chand, an Indian sprinter also caught by the regulation, challenged the IAAF policy. Lawyers for each of the parties produced contrasting medical advice on the effect of testosterone in intersex athletes.

The CAS ruled that the science was unclear on intersex runners, finding that their advantage was not in an order of magnitude above other benefits, from being born with “fast-twitch muscle fibres” that aid explosive sprinting to better access to specialised training.

The court gave the IAAF a deadline of July 2017 to return with more scientific research or the policy will become void. In Rio, Chand became the first Indian woman to compete in the Olympic 100m in 36 years.

“We felt that for good scientific reasons that [testosterone] was a contributory factor,” said Lord Coe. “CAS saw otherwise. We accepted that adjudication. But it is very clear that we were effectively asked to do homework, go away and revisit this. That is exactly what we’re doing.”

The International Olympic Committee, the governing body for the games, also accepted the decision but asked the IAAF and others to continue research.

Dr Richard Budgett, IOC medical and scientific director, said: “Whether there is a cut-off in the continuum between someone living as a male or female, and whether it is appropriate to use such a cut-off as an eligibility criteria for sport — that is a question for which we don’t have the answer yet.”

That question will be debated long after Semenya’s final on Saturday.

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