I can’t stop thinking about Feagaiga Stowers. Or rather a picture of the 18-year-old Samoan, standing on the second step of a podium last week, looking stoic but sad. By any measure Stowers is a remarkable woman. As a child she was a victim of sexual violence, and sought refuge at a Victim Support Group where she began weightlifting and went from being “shy and hopeless” – her words – to a world junior and Commonwealth Games champion. Yet having been chosen to be the flag bearer at the Pacific Games, she missed out on two gold medals to a 41-year-old, Laurel Hubbard, who looks set to be one of the biggest stories of Tokyo 2020.

The reason? Hubbard is a transgender athlete, who as a male named Gavin did not make a ripple on the international stage until becoming a woman in her mid‑30s. Now, though, Hubbard is a realistic contender for an Olympic medal and creating a tsunami of protests from women who fear she has an unfair advantage because of the residual benefits of being a male. As the Australian weightlifter Deborah Acason put it: “I feel that if it’s not even, why are we doing the sport?” The Samoan prime minister has also weighed in.

This is a contentious and complicated issue. It cuts across sex and gender, fairness and inclusivity. There is also no solution that will satisfy those who insist women’s sport needs to be protected, and others who believe gender identification trumps everything. As one leading expert put it to me last week: “How can you be fair to everyone? It is almost impossible.” Anyone who enters the debate risks walking on a minefield.

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But when it comes to the science, a new academic paper in the BMJ Journal of Ethics argues that elite transgender women do maintain an advantage when they transition – and that the current International Olympic Committee policies create what they call an “intolerable unfairness”, because testosterone has much more of an advantage on nearly every sport as opposed to say, being tall, having a large wingspan, or coming from a richer country, which the scientists say is more of a “tolerable unfairness” as it only provides a benefit in some sports.

This debate involves numbers, and it can be easy to switch off. But bear in mind the following: women’s testosterone levels range from 0.52 to 2.42 nanomoles per litre, while men’s are 10.41 to 34.70nmol/L. Meanwhile the IOC guidelines for transgender athletes, published in 2015, require them to drop their levels to 10nmol/L for 12 months in order to compete as women – a figure much higher than normal.

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The academics point out that the IOC is making two fundamental assumptions. First, that testosterone is a massive factor in sport. Second, that trans women with levels under 10n/mol have mitigated the performance advantage of their former male physiology. On the first point the IOC is undoubtedly right. Women have 44% less upper body strength “providing men an advantage for sports like boxing, weightlifting and skiing”, say the academics, while muscle mass differences lead to “decreased trunk and lower body strength by 64% and 72% respectively in women”. Men also have, on average, larger hearts, greater lung capacity and stronger bones.

As the academics note: “These differences largely underwrite the significant differences in world record times and distances set by men and women.” That, of course, is why women’s sport is protected. If it wasn’t there would be no Serena Williams, no Dina Asher-Smith, no Megan Rapinoe as role models for millions: Novak Djokovic, Christian Coleman and Lionel Messi would smash them into dust every time.

So what happens when an elite transgender athlete lowers their testosterone to 10nmol/L? Here the academics argue the IOC is wrong, saying its rule does not “entirely mitigate the physiology of prior exposure to testosterone and other Y-chromosome genetic determinants.” For instance when men’s testosterone was reduced to 8.8nmol/L for 20 weeks in one study, they did not lose significant muscle mass or power.

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Given the IOC’s transgender rules clearly state that “the overriding sporting objective is and remains the guarantee of fair competition” most experts had expected a new policy reducing the level to 5nmol/L before Tokyo. My understanding, however, is that is no longer the case – and that the current limit will remain in place.

In its defence, the IOC says international sports federations are free to decide their own transgender policies. But sports are cautious about doing anything without the IOC’s lead. So what we get is essentially a game of hot potato, with both sides passing the issues to the other, only with the music never stopping.

How might the impasse be broken? The authors of the BMJ piece argue that it is time to end male and female sections and instead put athletes in categories based on factors such as their weight, VO2 max, physiology and so on – ensuring that sport is completely inclusive for trans athletes and women. I can’t see that working.

More likely is that testosterone levels for transgender women will eventually be based on their sport. So a weightlifter might have to lower their levels to 2.5nmol/L, while with track and field it might be double that. Either way, a guiding principle surely has to be that anyone who transitions does not leap from being bog-average to world beater in a year.

The other important point is that this debate must be had. No longer can men tell women, such as Martina Navratilova, that when they stick up for a separate women’s sport category that they are ignorant or prejudiced. Such comments carry a pungent whiff of misogyny from the bad old days – when women were told to know their place, and kept on the margins of sport. It’s not always trans athletes who are underdogs either. Just ask Feagaiga Stowers.