By Karolos Grohmann
TOKYO, July 29 (Reuters) - Male puberty is not the sole factor in ascertaining whether transgender athletes have an advantage over competitors, the International Olympic Committee's medical chief said on Thursday.
New Zealand's weightlifter Laurel Hubbard is set to become the first transgender athlete to compete at an Olympics when she starts in the heavyweight 87+kg category on Aug. 2 at the Tokyo Games. The 43-year-old's inclusion has been extremely divisive, with some questioning the fairness of transgender athletes competing against women.
Hubbard, who will be the oldest lifter at the Games, had competed in men's weightlifting competitions before transitioning in 2013.
Scientists have pointed to the biological advantages of those who have gone through puberty as males, such as bone and muscle density and some athletes have publicly opposed her Olympic participation.
Supporters of transgender inclusion argue the process of transition decreases that advantage considerably.
"Laurel Hubbard is a woman competing under rules of her federation," IOC medical director Richard Budgett told a news conference on Thursday.
"When it comes to advantages and disadvantages there is more to learn, there is always more science."
"There are a lot of aspects of physiology and anatomy and the mental side that contribute to an elite performance and it is very difficult to say 'yes she has an advantage because she went through male puberty', when there are so many other factors to take into account. It is not simple."
The IOC had cleared the way in 2015 for transgender athletes to compete at the Games as women, provided their testosterone levels are below 10 nanomoles per litre for at least 12 months before their first competition.
There is now an ongoing IOC-led review of all the scientific data to determine a new framework that would allow international federations to take decisions for their sport individually, according to the IOC.
"There is a lot of disagreement across the whole world of sport and beyond on this issue of eligibility," Budgett said.
Australia's weightlifting federation had tried to block Hubbard from competing in the women's event at the 2018 Commonwealth Games but has been supportive of her selection for Tokyo.
"Everyone agrees transgender women are women but it is a matter of eligibility for sport and particular events. It really has to be very sports-specific." (Reporting by Karolos Grohmann Editing by Shri Navaratnam)
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