Currently, as The Guardian recently reported, “athletes who transition from male to female can compete in the women’s category without requiring surgery to remove their testes provided their total testosterone level in serum is kept below 10 nanomoles per litre for at least 12 months.”
Even among those who believe trans women athletes should be able to compete against cis women, this is controversial. After all, the “normal” testosterone range for a woman is 0.12 to 1.79 nmol/l and the average for a man is 7.7 to 29.4 nmol/l. In other words, the trans woman athlete would be eligible to contend if their T levels are on the lower side for a male—but still significantly higher than the average woman.
Although bone density changes in male-to-female trans people, other advantages don’t magically disappear. If one trains for years with male testosterone levels, it’s not as if all of that extra muscle mass withers away. Over the summer, The Journal of Medical Ethics concluded not only that the current IOC testosterone standard is unfair to biological women but also that “Science demonstrates that high testosterone and other male physiology provides a performance advantage in sport suggesting that trans women retain some of that advantage.”