Lausanne - Female transgender athletes must lower their testosterone levels by half under new regulations introduced by the IAAF, bringing the rules into line with those for hyperandrogenous competitors such as Caster Semenya.
Under the new eligibility rules announced this week, transgender athletes are no longer required to be recognised by law in their new gender but only need to provide a "signed declaration" that they identify as female.
The International Association of Athletics Federations (IAAF) Council, which met in Doha, approved rules that require the concentration of testosterone in a female transgender athlete to be less than five nanomoles per litre continuously for a period of at least 12 months prior to being declared eligible.
The previous limit was 10 nanomoles.
Athletes must maintain their testosterone levels below the five-nanomole limit to keep their eligibility to compete in the female category.
"Under the new regulations a transgender female athlete is no longer required to be recognised by law in her new gender but should provide a signed declaration that her gender identity is female," an IAAF statement said.
"She must demonstrate to the satisfaction of the expert panel that the concentration of testosterone in her serum has been less than 5nmol/L continuously for a period of at least 12 months prior to being declared eligible, and must keep her serum testosterone concentration below that level to maintain her eligibility to compete in the female category."
Similar rules apply to athletes with differences of sexual development (DSD), or hyperandrogenism, such as Semenya, South Africa's double Olympic 800 metres champion who is currently ineligible to compete and was ruled out of this year's world championships.
Semenya is taking legal action to try to reverse the current IAAF ruling.