Updated February 13, 2025 at 14:48 PM ET
President Trump wants to ban transgender athletes from competing in women's sports due to a supposed biological advantage.
But what does science say?
Dr. Bradley Anawalt, an endocrinologist and professor of medicine at the University of Washington, said there appears to be no competitive advantage between boys and girls before they undergo puberty around the ages of 11 or 12.
"So the whole conversation about the effects of hormone therapy for transgender athletes is irrelevant for anybody who hasn't gone through puberty," said Anawalt, who has advised a number of sports associations.
Earlier this month, Trump signed an executive order seeking to ban trans athletes from women's sports. It has now drawn a lawsuit from two transgender high school students in New Hampshire, who are asking a federal court to add the president to a lawsuit originally filed last year over their eligibility to play girls sports at school.
Anawalt told Morning Edition's Michel Martin that, in the overall debate about trans athletes in competitive sports, fairness and inclusivity are two virtues that may be at odds.
This interview has been edited for length and clarity.
Michel Martin: So what effect might gender affirming care have on a trans athlete and their abilities? Does it matter at what age they transition?
Dr. Bradley Anawalt: It really does. The best data is from military recruits, and there are a couple of recent studies, one published in 2020 and one in 2023. They looked at cis men, cis women, trans man and trans women. How many steps you can do in a minute, how many push ups you can do in a minute, and how fast you can run 1.5 miles. And what they found in that study was that trans women remained faster for up to two years after the initiation of gender affirming hormone therapy. At four years, trans women continued to do more sit ups and push ups.
Martin: So would it not be reasonable then for people to have these concerns, at least in certain sports?
Anawalt: It would be reasonable to have concerns about the possibility of competitive advantage for trans women. The difficulty of answering this question, based on the scientific evidence, is there is an enormous difference between military recruits compared to elite athletes that are doing four, six, eight or more hours a day of training.
Martin: You try to avoid terms like fair versus unfair in this conversation. Could you just say more about that?
Anawalt: It's not that I dislike using the term fair and the term unfair. It's that we have two virtues, two values that are in conflict with each other. One is whether or not it is fair for trans women to compete in sports as females.
And then there's inclusivity. One of the beauties of sport is let's let everybody play. We just need to acknowledge the other part of the equation, which is that there's always been inequities in sport. Somebody who's born taller than somebody who is shorter and plays basketball, we really don't have this conversation about the potential competitive advantage for people participating in ballet or theater. Peter Pan is almost always played by an adult woman because an adult can act with greater artistry and maturity based on age and experience.
Martin: Is there any way to disentangle questions of endocrinology? What the data tells us, what the science tells us from all the heat that has now surrounded this issue?
Anawalt: I can see the beginnings of the way to unspool the tension on this. We're trying to be fair and we're trying to be inclusive. And they're both very important. And at times, there may be conflict in those. And then we're going to have to have a measured, thoughtful approach to how we figure out a way to be as fair as possible, but also be inclusive as possible.
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