Now transgender athletes look set to compete at the Olympic Games for the first time without first having to undergo gender reassignment surgery.
Medical chiefs at the International Olympic Committee
(IOC) have recommended the change which could mean transgender athletes would be more readily able to take part in this summer's Olympics in Rio de Janeiro
as well as other international events.
Transgender athletes have been allowed to compete at the Games since 2004 but only after surgery, having undergone a minimum of two years hormone therapy and being legally recognized as their changed gender.
Headed by Professor Ugur Erdener, the IOC medical hearing's findings
said that, "it is necessary to ensure in so far as possible that trans athletes are not excluded from the opportunity to participate in sporting competition," while still ensuring "the guarantee of fair competition."
The hearing concluded that insisting on surgery "may be inconsistent with developing legislation and notions of human rights."
As a result, it is proposed that athletes "who transition from female to male are eligible to compete in the male category without restriction."
The new IOC guidelines -- published by the organization as a pdf
-- provide guidance to international sports federations, but as yet are not rules or regulations.
The revised thinking stems from an IOC meeting in November on "Sex Reassignment and Hyperandrogenism," and were first picked up on by journalist Cyd Zeigler and published by Outsports.com
in recent days.
The IOC was not immediately available for comment when contacted by CNN.
Athletes, though, who transition from male to female must declare their gender identity as female and show that their testosterone seem level is below 10 nanomols per liter for at least 12 months before competing, that the testosterone level must remain below this while competing and that athletes may need to undergo testing to prove this.
Among those at the IOC hearing were Dr Richard Budgett -- the organization's medical director -- who said he hoped the recommendation would lead other sports to make it legally binding.
Budgett was reported as saying by The Associated Press
: "This is a scientific consensus paper not a rule or regulation. It is the advice of the medical and scientific commission and what we consider the best advice.
"I don't think many federations have rules on defining eligibility of transgender individuals. This should give them the confidence and stimulus to put these rules in place."
The new guidelines potentially pave the way for transgender athletes like Chris Mosier
The American had qualified for the World Duathlon Championships but his place -- under current guidelines -- was still in doubt.
"I think we did it! I think it is official," he said on Twitter
in response to the news.