Elite swim coach Mark Bone has applauded his sport's stance on limiting transgender athletes competing against women.
World swimming body FINA has banned any transgender from women's competition, if they have experienced any stage of male puberty, and will consider creating a separate category, so they can compete amongst themselves.
Supported by 71 percent of member nations, including New Zealand, the ruling has divided public opinion, but sparked similar response from other sports struggling with the issue.
Bone has told AM the decision makes sense to anyone in the sport.
"To be fair, I was really delighted with FINA," he said. "Many times, they've made bad decisions, as I think a lot of world governing bodies have made bad decisions over the years, but this is a good decision.
"They've listened to science and they've backed it up with science. They've had a group of sports medicine and science, physiologists, biomechanists and also litigation - they've had the legal perspective.
"It's a great decision, when you look at fairness and fairness to women, in particular."
Bone - who has overseen NZ Olympic and Commonwealth Games swim teams, and worked with Olympic triathlon medallists Hamish Carter and Bevan Docherty - insists anyone born as a male will have inherent benefits that won't diminish through lowering of testosterone levels.
"You can lower testosterone, but it doesn't change the basic structure of what is a biological male at birth," he said. "That is great bone density, great limb length, bigger heart, bigger lungs... testosterone lowering is not going to affect that."
The issue has come to head in swimming, with the emergence of American collegiate champion Lia Thomas, who began her career on the Pennsylvannia University men's team, before transitioning to a woman.
In March, she made history as the first openly transgender athlete to capture a division I national collegiate title, when she won the women's 500 yard freestyle.
"You have to look at that, as a pure female, is that being fair to the female athletes?" added Bone.
"You've got to look at a biological female coming through the ranks and their own development. They want to be protected from that, so it's all about fairness and equality for them as well."
Bone isn't aware of any transgender swimmers in New Zealand, but hopes clearcut guidelines and a specialised category may encourage them to emerge.
"There does need to be a new category," he said. "You need to be able to have full inclusion, because the IOC [Olympics] is all about full inclusion.
"But the reality is this, if you had Michael Phelps or Usain Bolt suddenly become transgender, and raced in female events, what sort of records would be broken? You'd have an outcry."