From Fina’s Science Group.
The Science Group reported that biological sex is a key determinant of athletic performance, with males outperforming females in sports (including Aquatics sports) that are primarily determined by neuromuscular, cardiovascular, and respiratory function, and anthropometrics including body and limb size. The extent of the male/female performance gap varies by sport and competition, but the gap universally emerges starting from the onset of puberty. The group reported that there are sex-linked biological differences in Aquatics, especially among elite athletes, that are largely the result of the substantially higher levels of testosterone to which males are exposed from puberty onwards. Prior to puberty, testosterone levels are similar in females and males. During puberty, however, testes-derived testosterone concentrations increase 20-fold in males, while testosterone concentrations remain low in females so that post-pubescent males have circulating testosterone concentrations at least 15 times higher than post-pubescent females (15-20 nmol/L in adult males versus c.1 nmol/L in typical females of any age). High testosterone levels generate not only anatomical divergence in the reproductive system but also measurably different body types/compositions between sexes.
According to the Science Group, if gender-affirming male-to-female transition consistent with the medical standard of care is initiated after the onset of puberty, it will blunt some, but not all, of the effects of testosterone on body structure, muscle function, and other determinants of performance, but there will be persistent legacy effects that will give male-to-female transgender athletes (transgender women) a relative performance advantage over biological females. A biological female athlete cannot overcome that advantage through training or nutrition. Nor can they take additional testosterone to obtain the same advantage, because testosterone is a prohibited substance under the World Anti-Doping Code.
So..How is Tanner Stage 2 accurately determined if puberty in males can begin anywhere from 9-13 years old? If males from 9-11 years old show Tanner Stage 2 and are not accurately diagnosed as beginning puberty, then the “legacy effects...will give male-to-female transgender athletes (transgender women) a relative performance advantage over biological females...”