Advocates of women’s sports say that allowing athletes who were born male to compete as women puts biological females at a competitive disadvantage. Supporters of transgender inclusion in women’s sports admit that men have an athletic advantage over women but believe that those advantages can be mitigated by hormone therapy. Recently, NBC analyst Jo Yurcaba suggested that there is “very little scientific evidence that [the advantages conveyed by male puberty] carry over for trans women after transition.” Is this accurate?
False. Completely make believe.
Scientific studies consistently demonstrate that the 20-fold boost in testosterone brought on by male puberty creates a significant, and lasting, athletic advantage. Because most American boys begin puberty between ages 9 and 14, a significant male-female athletic differential is present by age 15.
Suppressing one’s testosterone after the advent of male puberty can reduce a person’s athletic capacity, but it is insufficient to close the male-female athletic gap. While testosterone is the most significant factor in the male-female athletic differential, it is not the only factor. There are, for example, over 3000 genes that contribute to muscle differences between human males and females, and genetic differences may create different muscle responses to training even between those men and women with equal concentrations of circulating testosterone.
Moreover, many of the changes brought about by the increase in testosterone during male puberty (such as changes to skeletal architecture) are permanent and unalterable. Testosterone suppression will not, for example, make a person shorter or reduce a person’s wingspan.
Studies indicate that a year of testosterone suppression does not reduce running speed to normal female levels. It is perhaps not surprising, then, that two years after undergoing hormone suppression treatment, college athlete CeCe (formerly Craig) Telfer ran the indoor 200-meter dash in 24.45 seconds—faster than Telfer’s 2017 pre-transition time of 24.64.
Nor can testosterone suppression reduce male strength to normal female levels. Indeed, studies show that testosterone suppression removes only about 5-10% of the male strength advantage, a difference that some athletes may be able to make up with rigorous athletic training.
An individual’s testosterone levels are not, therefore, precise predictors of athletic performance. And hormone therapy does not come close to leveling the proverbial playing field.
Learn more about the male-female athletic advantage in COMPETITION: Title IX, Male-Bodied Athletes, and the Threat to Women’s Sports.