Trans Sports Dominate Culture Wars. But What Do Scientists Think?
The debate over trans athletes has reached a fever pitch. Riley Gaines, a former collegiate swimmer who tied for fifth place with a trans swimmer in 2022, has become a star in the world of conservative politics. Former NBA players Enes Kanter Freedom and Royce White recently announced their intentions to enter the WNBA draft and “expose” the league’s lack of policy for transgender players. And less than two months out from the November midterms, trans athletes are shaping up to be an issue on voters’ minds as they head to the polls.
All of this noise has created little room for thoughtful conversation. We wanted to change that.
In this episode of “UNCLOSETED with Spencer Macnaughton,” we sit down with three of the leading researchers and scientists in this field to get an evidence-based understanding of what we know—and don’t know—about the physiological differences between cis and trans women and girls in sports.
Watch the full interview above or read the transcript here:
Spencer Macnaughton: Hi everyone, welcome back to UNCLOSETED with me, Spencer Macnaughton. Today, we’ve assembled a panel of three scientists whose work looks at trans people in sports. First, Dr. DJ Oberlin is an assistant professor in the exercise science program at Lehman College, CUNY. Second, we have Dr. Gregory Brown, an exercise science professor at University of Nebraska, Kearney, and a fellow at the American College of Sports Medicine, who is the faculty adviser for his school’s Turning Point USA chapter. And finally, we have Dr. Joanna Harper, who holds a PhD in exercise science, published the first peer-reviewed study on trans athletes and has advised organizations such as the International Olympic Committee and World Athletics on trans issues. All, thank you so much for speaking with me and Uncloseted Media today.
DJ Oberlin: Thanks for having us.
Gregory Brown: Yeah, thank you very much.
SM: I’m excited to have folks here who have studied this topic and are informed, I believe, for the most part, through science and evidence. I wanna start though by saying we’re in a moment where the debate is so, so hot. I wanna get a sense of where you think we are with that debate and what does that do for folks who really wanna get out research and science behind this nuanced conversation?
Joanna Harper: Well, I can tell you from a very personal point of view, I was involved with a research study looking at fitness test results in trans adolescents. Last year, six United States senators spoke out against the study. The study was privately funded, but they put enough political pressure on our sponsor that they pulled the funding.
SM: And the sponsor was Nike, correct?
JH: Yeah, that kind of hit pretty hard at home for me. Lost the study, lost my job, lost the funding.
SM: And what do you attribute? Because presumably, that study was nonpartisan, right? What do you attribute the kibosh from those senators being?
JH: Well, the senators said things like the study was supporting radical trans ideology, which of course it wasn’t at all. We were looking at fitness test results, which should be a pretty nonpolitical thing.
SM: But why do you guys think this has taken such a center stage in the kind of narrative, in the media?
GB: If I may, one thing I think is that it is kind of an obvious challenge to what has been normal. We’ve had sex-segregated sports because the sex-based differences in sports performance are really blatantly obvious. And then to say, “But if a male identifies as a woman or a female identifies as a man, we should therefore accommodate them,” it becomes a flashpoint. How many thousands of years of sex-segregated sports or other things, and then challenging people’s common sense? So as you mentioned earlier, regardless of whether there’s good science or not, it makes good headlines.
DO: If I could also point out that it’s such a vanishingly small percent of the population. Using it as a wedge issue, you’re not alienating a large group of a voter base anywhere.
SM: And obviously, it’s tough to even start this conversation from an apolitical perspective, because for example, Greg, the things you just said about common sense, about identifying as a man, some folks would see that as, or the latter at least, as implicitly transphobic, suggesting that trans people don’t exist, or common sense as a dog whistle leveraged by the right wing. So it is tough to get into these conversations in a way that is completely apolitical. But let’s try!
GB: And I appreciate that because a lot of times what is said, for or against trans inclusion in sports, comes off and one side or the other claims it’s a dog whistle when it’s not intended to be. If you’re arguing over the words, it’s hard to get to the meat of the subject.
SM: Well, let’s table the words for a second, and let’s talk about the research and what we know. So, if we simply look at cis women and cis men and compare stats in most professional sporting environments, it does seem like there are differences. If you look at the, you know, fastest person in men’s sports, competing in a 100-meter dash, the fastest serve in tennis, the number of slam dunks in basketball, these kinds of things, like the statistics go on and on and on. Is that fair? Am I reading that correctly for the viewer who isn’t sure?
JH: Very substantial differences. Anyone who goes through a testosterone-fueled puberty, regardless of their gender identity or how they were identified at birth gain very substantial athletic advantages over anyone who doesn’t. That is simply not controversial among exercise scientists.
SM: But it gets more complicated with trans girls and women because you’re adding different things into the equation. There are things like puberty blockers. There are things like hormone replacement therapy. So what do we know again from the science about what happens when you add those things in?
JH: Well, Greg and I are probably gonna disagree on the interpretation of the data. There’s no doubt that when trans women go on hormone therapy, they block—or we block because I’m a trans woman myself—we block testosterone and add estrogen. And that makes very substantial differences in athletic performance, but it doesn’t turn trans women into cis women, and there are differences that remain.
GB: Thanks, Joanna, I appreciate that. You know, again, looking for where we do agree is, yes, there are very substantial differences. Just in the last few years, we’ve seen quite a bit of research that’s published showing those differences are present before puberty. So before puberty, boys run faster than girls, males run faster than females. And so then the question comes in with puberty blockers. Does that erase those differences? And honestly at this point in time, we cannot say, “Yes a 12-year-old trans girl would be able to compete equally with 12-year-old cis girls” because those data don’t exist, but we do know that the differences in athletic performance based on sex are present before puberty and they’re magnified by puberty.
SM: DJ and Joanna, I want you to respond to that. Do you agree with that?
JH: So, as Greg said, they’re magnified by puberty, but the differences before puberty are substantially smaller. And I think they’re small enough that some people could argue that they are more sociological than physiological.
SM: Like there’s data to suggest that boys get more encouragement to play in sports. Boys are told to play in sports more, these sorts of things. Is that what you’re suggesting?
JH: Yes. In truth, I think it’s probably a combination of physiology and sociology, but the differences are certainly much smaller before puberty than after.
SM: But you don’t reject that physiology could play into it to a certain extent before puberty.
JH: Not just could, probably does.
SM: Probably does. OK, DJ, get in here.
DO: Yes, everybody’s going to agree there’s sex differences that can be measured. With young boys and young girls, there are slight differences as my colleagues have said, but I kind of agree with Joanna that we don’t know to what extent it’s sociologically. So I was recently reviewing a paper looking at different predictors of performance in adolescence, and they show that the amount of time spent in little league sports and playing organized sports is so much greater among the young boys than it is the young girls, that then if you go to do a performance-based assessment of fitness, the boys are almost certainly going to perform better.
SM: So it sounds like it’s biology and sociology that are playing into it in most cases.
DO: Yeah, and I’m not sure that we can completely disentangle. There is a small, what they would call “mini puberty,” where endocrines fluctuate a little bit very, very early in life. But generally we don’t see these huge differences in hormone levels until puberty occurs. So it’s curious to try to think of what is the physiologic basis, whereas some of those sociologic things are already well documented.
SM: And I think there’s two conversations we can have here about rules and regulations. One at the very top professional level and then one at the recreational junior high level. Let’s start at the highest level of sports. So as of now in professional sports, there’s a great deal of variance as it relates to inclusion of trans women. But in March, the International Olympic Committee announced a policy that limits the female category in the Olympics to biological females using a mandatory one-time genetic test. That essentially, as far as I’m reading it, means trans women are not allowed to compete in the Olympics in women’s sports. Based on everything you guys know about the research and the science at this time, did the IOC make the right decision?
JH: I don’t think that this was the correct decision, but I will acknowledge that it’s a very difficult question at elite levels, and there’s no magic bullet. There’s no policy that is going to appease everyone or perhaps even the majority of people.
SM: If you were a policymaker, what would you have done?
JH: So, when I was part of the policy making group, we recommended that at high levels of sport, trans women should be required to reduce testosterone to female typical values and keep them.
SM: And DJ, Greg, do you agree with Joanna or do you think the IOC made the right decision?
GB: I think the IOC made the right decision. I do think that individuals who have an active SRY gene, they’re going to experience male development, they’re gonna experience male typical athletic advantages. And the research to date does not indicate that those advantages can be erased through gender-affirming hormone therapy.
SM: DJ?
DO: I don’t know how I would have regulated it. I know previously they were doing it by sports, which I’m sure you guys have seen Emma Hilton’s paper where she shows the proportion of advantage from males with testosterone varies by what kind of competition you’re doing. And so having different categories for men and women certainly makes sense in some cases? But not in all cases.
SM: Joanna, you mentioned nanomoles per liter of testosterone could be a variable that should be considered. And if trans women can get the levels low enough, right? They should be able to compete in the Olympics, for example. But I think we spoke a few years ago on the phone and you mentioned there are other factors like heart size, lung size [and] wingspan. So what makes you say testosterone is the measurements in your opinion that can get us to equitability?
JH: Well, not necessarily equitability, but I think that if trans women and women with XY DSDs reduce testosterone to female typical values, that in most sports, the mitigation of the advantage of going through a testosterone fueled puberty is sufficient to make the advantages small enough that trans women and cis women can engage one another in meaningful competition. Not necessarily exactly equal, but I think the differences can be small enough that we have meaningful competition between those two groups.
DO: I think that’s sort of the important contention, though. That was something I raised in my review paper, which is, can we ever have equity between any two athletes? As soon as you have two people, there are certain advantages and disadvantages, whether they’re cis or trans, and so is being transgender so dramatically different than having a huge height advantage, having an overly muscular frame or something else, that we have to outright ban them?
SM: And I guess some people might push back on that and say, OK, for trans women who have had no gender-affirming care at all, but who still identify as trans, like there obviously would be no differences between cis men and cis women in that case, right? So should there just be one league for everyone, right? A genderless league? And then I think people would say, if you line up the stats, you would have all people assigned male at birth in the top 1,000 of that sport. So, is that not kind of countering the point you just made there to a certain extent?
DO: It is, but I’m saying that nobody’s arguing to make sports more equitable so that I can compete even though I would be blown away by any trained athlete. Nobody says, “Why do we let all these tall people play basketball? Let the short people also play basketball.”
SM: And Greg, what do you think?
GB: I disagree that the data show that the differences between trans women and cis women become close enough because what we have is an incomplete understanding. We have lots and lots of information on the differences between males and females in body height, in muscle mass, in lung capacity, in heart size, in bone mineral density. All these factors that give male advantage. And gender-affirming hormone therapy doesn’t erase all of those. Trans women are still five inches taller than cis women. Trans women still have more lean body mass than cis women. And lean body mass is really the engine that drives athletic performance. And so to then ignore that in favor of, well, we don’t know, is not necessarily making an evidence-based decision. I think to state that reducing testosterone eliminates male advantage is an extraordinary claim that is not supported by extraordinary evidence.
JH: And neither DJ nor I have said it eliminates; we’ve used words like mitigating or bringing it to the ballpark. So there are people who do say that, but nobody in this panel.
DO: That’s why we’re trying to do the research to see.
SM: Yeah, and it sounds like a lot is just unconfirmed, there’s no magic bullet answer. Would everyone agree with that? Maybe Greg would not agree with it.
DO: I certainly agree with that.
JH: I also think that, but I think Greg thinks we found the magic bullet.
GB: As a scientist, I’m open to if new evidence comes through, showing more convincingly that we could erase male advantages, I’m open to those possibilities. But it needs a lot more data and information. Or, again, bring them close enough. We don’t let a wrestler who’s two pounds overweight go into a lighter weight category because they’re close enough, they have to make that weight category. And so I think the same goes with the sex-based categories.
SM: But if you’re somebody who wants to treat all humans with dignity and respect, trans girls and women, is there not an argument that, OK, we’ve mitigated a lot through these factors and now let’s let people play. We have so much research to know how playing in sports is healthy. It’s important. How playing among your peers is critical. And obviously as it relates to gender dysphoria, being able to play on teams that match your gender identity is crucial for the mental health of many trans people. And in certain cases, many would argue it’s lifesaving. Can we not add that in as kind of a really important and meaningful part of this equation?
JH: Of course, it’s part of the equation. It’s one of the things that most distresses me about the bans. The reality is that no one has the right to compete in the Olympics. And if the IOC makes rules for female eligibility, that’s their prerogative to do so. But what happens is this idea that trans women shouldn’t be allowed to compete as the people that we are trickles down and many states, many countries, don’t let trans girls play sports. Again we’re not talking about olympic competition, we’re talking about playing sports. Being part of a team competing, participating with your peers. And if trans girls are not allowed to participate in sports, it is extraordinarily detrimental for their lives.
DO: I’d also kind of add to that just because, Greg, you had brought up needing evidence, and I agree. But it seems like we’ve got things backwards where we ban until proven otherwise, and we’re calling them guilty until innocent. Why not let people play and then once they’ve dominated everything, you’ll say, oh, wow, I can’t believe that every leading player in every sport is trans. I guess they do have an advantage.
GB: So, DJ, I think we’re looking at that differently. I’m saying, why are we changing, in essence, the status quo without evidence? We know these sex-based differences exist, and so why are trying to say those sex-base differences then don’t exist in certain circumstances until we have convincing evidence? And sometimes the compassion in this case is also being compassionate for the female athletes, the girls and the women, cis girls, cis women, and letting them have fair, safe competition without the inclusion of male athletic advantage.
SM: And Greg, I want to ask, the elephant in the room is, as I said in the intros, you serve as a faculty adviser to your school’s chapter of Turning Point USA. That’s an organization that has pushed the idea that trans people are, quote, “coming for your kids.” It consistently misgenders trans people. Charlie Kirk, the late person who led Turning Point USA was virulently transphobic in many instances. So I want to give you the opportunity to, you know, say how can we, as an audience, feel confident in your position and that it’s one rooted in science rather than animus.
GB: I appreciate you bringing that up. I really do. As the adviser for Turning Point USA, basically my job is to make sure that paperwork is getting filed between the students and the university. I haven’t signed any kind of pledge of allegiance to Turning Point USA. I honestly haven’t sat down and looked at a lot of their materials to know what the Turning Point USA positions are. I had a student that asked me to be the adviser, and so I’ve been the adviser.
SM: But if you’re signing up to be an adviser of a group and you’re somebody who looks into the participation of people in sports in this way, isn’t it on you to research a group and see if there’s a massive ideological bent on the existence of a population?
GB: You know, and you bring up a good question. I appreciate you challenging me on this. I have never, to my knowledge, expressed animus towards transgender individuals. I believe that transgender individuals, they’re our fellow human beings. And when you look at the papers that I have written, they are very solidly based on the science and do acknowledge, for instance, on the research I’ve done on pre-puberty children, acknowledging that yes, there may be social factors involved. So I think I’ve been very unbiased and straightforward in my scientific assessment on this.
SM: Fair, and just speaking as a cisgender person here, if I compare it, if I see somebody’s researching conversion therapy, let’s say all day, and then the faculty adviser for an anti-gay group on campus, I would feel very, very reticent to believe your research at that point is not fueled with bias and with animus toward the group that you’re looking at, but people can feel confident that your research is solid and isn’t fueled by any ideology of the groups that you are affiliated with. Even if it’s as simple as being the faculty adviser?
GB: I think so. I believe so.
JH: And if I may say something on Greg’s point…
SM: Yeah, no, I’d love to and I don’t, again, it needs to be said just because people are gonna see that intro and have thoughts to be honest, yeah.
JH: So, Greg saw what Uncloseted Media was, and he came on here and he—
SM: So did Pete Hegseth’s pastor who said he wants to execute gay people. Go ahead, sorry.
JH: So I think somebody who was truly transphobic probably wouldn’t have joined this panel.
SM: Back to the science, the IOC has made their decision. I know Greg, where you stand now on this, but DJ, Joanna, obviously what’s happening with the WNBA. We see these former NBA players making a spectacle saying, “I wanna join, I want to be a part of this.” You know, it’s shock jock and I hope everyone here can agree useless and frankly kind of gross. Joanna, what would you do if you were consulting the WNBA?
JH: So the WNBA says that only women are allowed to play in the WNBA, but they haven’t gone any further than that. And so there’s some ambiguity there. And even if they said, for anyone whose sex at birth was male, we will need to look closer to see whether you qualify. And I think that would be a lot better than just saying only women are allowed to play in the WNBA. And so if I were advising them, which I’m not, that’s what I would say to them. And so I think they’ve left themselves a little bit open to this. Despite that, no trans woman has played in the league as far as we know. And so it’s certainly not that this inclusive policy has led to trans women taking over the league, but I think they could be a little more specific with their eligibility requirements.
SM: DJ, any thoughts?