What is fairness? In sport, everything. From childhood, we come to see the head start in the playground race, the shove in the goalmouth, a rogue thumb on the egg (and spoon) as unjust, and quickly, loudly, “Oi!” object. The same sense of probity works its way up into professional sport. Sandpapering a cricket ball: not fair. Boxing with loaded gloves: not fair. Intentional misrepresentation in Paralympic classification: not fair. Colluding with betting syndicates to fix a result: not fair. Doping in sport: not fair. We classify our sports in order to pitch like against like and to keep people safe. Heavyweight boxers never fight flyweights. From puberty, the sexes compete separately in most sports most of the time. These are long accepted norms. Or were. Laurel Hubbard, 43, is poised to become the first transgender Olympian after being picked for New Zealand’s weightlifting team. Bubbling up to be one of Tokyo’s big stories, this fixes the spotlight on to whether trans women have an unfair advantage over biological women, and pits those sometimes friends, sometimes foes, inclusion and fairness. By conflating gender and sex, I would argue we fudge the very reason we have sex categories in sport: the male performance advantage. Without a separate category for females, there would be no women in Olympic finals. Even in the 100m, one of the events with the smallest performance gap, approximately 10,000 men worldwide have personal bests faster than the current Olympic female champion, Elaine Thompson-Herah (10.70sec). And it’s not just track and field. While the smallest attainment gap between the sexes comes in running, rowing and swimming events (11-13%), this moves up to 16%-22% in track cycling, and between 29% and 34% when it comes to bowling cricket balls and weightlifting. The difference in punch power between men and women is a whopping 162%. Not, then, to be sniffed at. But the International Olympic Committee tweaked its guidelines in 2015 to allow athletes such as Hubbard to compete in the women’s category, provided their total testosterone level in serum is kept below 10 nanomoles per litre for at least 12 months. Transgender men face no restrictions in the male category for obvious reasons. Increasingly, however, research is showing that these testosterone guidelines do not guarantee the “fair competition” the IOC was hoping for. Ross Tucker, a sports scientist and expert on testosterone advantage in sport, succinctly sums it up: “Lowering of testosterone is almost completely ineffective in taking away the biological differences between males and females.” There is just no proof that reducing testosterone takes away the advantage of muscle mass, strength, lean body mass, muscle size or bone density. Despite this new evidence from Drs Emma Hilton and Tommy Lundberg, the IOC has put off any further decisions making until after Tokyo and left it up to individual sports federations to decide their own transgender policies. Some have been bold, others have written their policies alongside trans lobby groups without consulting women’s organisations or sports scientists. Those questioning the narrative are accused of transphobia – as Martina Navratilova and Nicola Adams have discovered. The most common argument used in favour of inclusion is that sport is all about natural advantage and that being a trans woman is just another factor to add to the list alongside Michael Phelps’s size 14 feet and double-jointed ankles. The problem with this argument is that we don’t compete according to foot-size, but we do protect the integrity of women’s sport because the advantage gained from male puberty is so comprehensive in terms of speed, power, strength and so much else. Phelps’s feet gave him an advantage as a swimmer; male puberty gave him a much bigger advantage across the board. At the Beijing Olympics, he won the 200m freestyle in 1.42.96, breaking the world record. Federica Pellegrini broke the women’s world record at the same distance, finishing in 1.54.82 – a time that wouldn’t have got her into the men’s semi-finals. It wasn’t internalised misogyny slowing her down. Serena Williams told David Letterman that were she to play Andy Murray, “I would lose, 6-0, 6-0, in … maybe 10 minutes”. Male puberty and androgens give an advantage in a different stratosphere. Some claim that this debate is irrelevant as trans women aren’t winning everything, which is true. The simple explanation is that the athletes who have transitioned haven’t generally been good enough. As Tucker says, the best female cyclist will beat 99% of men, but the best men are 10-15% better. And anyway, regardless of whether trans women win or not – whether Hubbard wins or not – it is legitimate to question the rules that allow them in the competition, given the retained advantage. Given the safety issues in combat, collision and some team sports. Given the hidden exclusions, those women and girls who decide that a sport now isn’t for them. And the not so hidden ones: Kuinini “Nini” Manumua, the 21-year-old Tongan who would have gone to her first Olympics if Hubbard hadn’t been selected. The American cyclist Veronica Ivy (previously known as Rachel McKinnon) says hang the heartache, trans women are women and should simply be able to self-identify themselves into the women’s category at every level. This argument has got some traction. In which case, why bother having sex categories for sport at all? Just put everyone in together and watch biological males win the lot. I’d argue the opposite. The science is young. Stop. Breathe. Trans women should be able to live their sporting lives to the fullest so if research can find a way for them to participate in female sports without advantage, brilliant. Until then, remove the idea of gender altogether and revert to sex-based categories – a female category and an open category that can cater for trans men who have taken testosterone, trans women and men. But above all, there needs to be a realisation that you can’t always have it all. Just as women and trans men can’t dominate in men’s sports; and men can’t enter women’s sport; trans women shouldn’t be able to push open a door that was locked for a reason. It isn’t fair.