Much has been made about transgender women (trans women) participating in sports - competitive and recreational. Unfortunately much of the panic is unjustified, and efforts such as those of the Alberta Government to ban trans women from sports is horribly misguided.
The expressed fear is that because a transgender woman is assumed to have male characteristics that would provide an "unfair advantage" in sports (or in some contexts, might actually present a danger to other athletes in the field.
In this essay, I will explore the research literature and its current limitations, as well as the policy objectives related to government involvement in sports and recreation. Spoiler: It's not simple, and anyone who tells you that based on one attribute or another that a ban is justified, is kidding themselves.
Examining The Literature
The literature around sex differences in sport breaks into two major categories. The first are attempts to understand the differences between male and female athletes in terms of performance. Broadly speaking, these studies only involve cisgender athletes. The second group of studies are those which attempt to understand where transgender athletes fall in terms of performance.
To be clear, as Sinclair (2025) points out, there are no viable "tests" that will unequivocally tell you if someone is male or female. The blunt reality is that human biology is complex enough that simply looking for a Y chromosome, or the presence of the SRY gene really doesn't provide an adequate answer. Such efforts are at best misguided, at worst malicious.
Sex Differences In Athletics
This is a broad class of studies, and largely are helpful in developing clearer understandings of why there are marked differences in athletic performance between male and female athletes. Studies such as Hunter and colleagues (2023) document the role of sex hormones in the development of individuals, and the impact on athletic performance in very broad terms. Of course, it's fairly obvious that sex differences that emerge in puberty are a significant determinate of key characteristics that influence athletic performance.
These studies are limited in their ability to encompass the characteristics of transgender athletes, who effectively experience at least two rounds of puberty in their lives. To this point in time, there are very few studies that engage with transgender athletes and attempt to highlight where they stand in terms of performance. That doesn't mean that these studies have nothing to say regarding where transgender athletes belong, but rather we need to be very cautious in applying those studies to transgender athletes because they have complex characteristics that need to be better understood.
Transgender Athletes
There are only a relative handful of studies that attempt to explore the performance of transgender athletes at all. This is not terribly surprising, as with a small population like the transgender community, it is very difficult to recruit enough participants into a study to get results that can be generalized at all. Second, any study in this field faces a myriad of potentially confounding factors - ranging from the age at which a participant began to medically transition, to their genetic predisposition to certain body development.
While studies like Hamilton and colleagues (2024) and Roberts, Smalley, and Ahrendt (2021) do engage with transgender participants, these studies are cross-sectional rather than longitudinal and therefore have significant limitations in how they can be interpreted. Findings of apparent advantage in one domain or another do not really tell us whether or not a given athlete has an "unfair advantage".
In fact, what these findings really reveal is the underlying complexity of the questions:
Although transgender women have comparable absolute V̇O2max values to cisgender women, when normalised for body weight, transgender women’s cardiovascular fitness is lower than CM and women. Therefore, this research shows the potential complexity of transgender athlete physiology and its effects on the laboratory measures of physical performance. (Hamilton, et al, 2024). emphasis added
Similarly, Oberlin (2023) notes the following in their conclusion:
While trans athletes competing in various sports and athletic events raises interesting considerations of how certain morphologic and physiologic factors affect performance, these questions are not exclusive to trans individuals. There are wide variations within cisgender populations, even when excluding individuals with differences in sexual development (121, 139). It is expected that about 2.3% of a normally distributed population is likely to fall above two standard deviations from a population mean. These exceptional individuals may be those who are gifted and excel at some sport or athletic performance (121, 135, 140). emphasis added
To get a sense of how complex this gets, in one study, transgender women were found to be about 10% faster than their cisgender female counterparts in running (Roberts, Smalley, & Ahrendt, 2021). "Ahah! There's a clear advantage" you might say ... but is it really? This is where statistics can actually be a problem. What we don't know is how the transgender athletes compared with their peers in a variety of dimensions. Were they 10% faster than their cisgender counterparts who were of a similar height, or length of stride? In a situation like this, one has to delve quite deep into the details to figure out exactly what's going on.
Oberlin (2023) observed that follow-up work done relative to the work by Roberts et al (2021) found that the apparent advantage that trans women had in running was not in fact statistically significant relative to cis women.
The follow-up study by Chiccarelli et al. noted that equivalence testing [the Two One-Sided Test (TOST)] should be used in addition to standard hypothesis testing to compare transgender individuals with their cisgender counterparts. The study also made comparisons of trans individuals' own pre-transition and post-transition performance as percentiles for men or women (129). Using these approaches, the researchers showed that trans women performance on the 1.5 mile run was not statistically different from cis women times following two years of gender affirming hormone therapy and remained equivalent to cis women out to year four (874 ± 133 s vs. 876 ± 111 s.) (129). Oberlin (2023) emphasis added
Similarly, in Hamilton and colleagues (2024), trans women are found to have a markedly higher grip strength than their cisgender peers. Yet, when you normalize the numbers for non-fat tissue, the result is that the transgender women had equivalent power, just more non-fat mass. Again, one is tempted to leap to the conclusion that this represents an "unfair advantage". Except we don't really know because the trans women athletes also experience significant disadvantages compared to their cisgender counterparts in areas like aerobic capacity (Hamilton, et al, 2024). It seems counter-intuitive - a trans woman would be expected to have larger lungs, but they have less aerobic efficiency.
The real takeaway here is the underlying problem of assuming that any one attribute makes an "athletic advantage" in any one sport, much less all sports. The body, is ultimately a complex set of systems which need to be reviewed.
Study Types and Limitations
The first and most fundamental limitation that all studies involving transgender people suffer from is simply small sample sizes. The transgender population is small, and finding willing participants within that population is difficult for a variety of reasons. Sample sizes of even 100 participants are often very difficult to reach. This ultimately means that from a statistical standpoint, generalizing the results is impractical.
To date, the handful of studies that do engage with transgender athletes in a meaningful way are mostly what are called cross-sectional study designs. A cross-sectional design is a "moment in time" study, where you take There are a bunch of reasons that cross-sectional designs are problematic though. For example, Hamilton and colleagues (2024) identify a range of issues that are limitations of their findings:
The limitations of this study primarily relate to its cross-sectional design, making it challenging to establish causation or examine if the performance of athletes changes as a result of undergoing GAHT. Longitudinal studies are needed to examine how GAHT, and other factors impact athletes’ physiology and performance over time. Additionally, the composition of the study cohort may not fully represent the diversity of athletes in elite sports from worldwide populations. Athletes from various sporting disciplines and performance levels were included, and the athlete training intensity was self-reported. Therefore, the results may suffer from selection and recall bias.43 The results may not apply to all levels or ages of athletes, specifically as this research did not include any adolescent athletes competing at the national or international level. The athletes participating in the present study represented a variety of different sports, and this would have undoubtedly impacted the results of the study as different sports stress different training and sports modalities. (Hamilton, et al., 2024)
While Roberts (2021) uses a larger sample, and does implement a longitudinal component, its results are still intrinsically difficult to generalize across sport as a whole. Does it indicate a meaningful advantage for trans women in running? Only sort of, as follow-up work done subsequently found (Oberlin, 2023).
Longitudinal studies are not going to be a global solution either. There are a plethora of confounding factors that need to be considered ranging from the characteristics of the athletes themselves to the nature of the sports they are engaged in. A person who is an outstanding runner isn't guaranteed to be outstanding in a sport such as gymnastics. Any elite level analysis of trans athlete participation in a sport needs to reasonably, and intelligently, evaluate these factors individually.
Considerations For Further Study
This is a very complex domain, involving both developing a working understanding of transgender athletes and their development, as well as establishing in sport which characteristics are central to that sport and performance in it.
Transgender Development
There is a huge amount we do not know or fully understand about how transgender people develop and the effects of the various medical interventions have on the body's systems. From a sports perspective, we have to ask pointy questions about many things:
- When did the person begin to medically transition? (age, state of pubertal development, etc)
- How long has the person been in medical transition? (esp. HRT)
- Long term effects of HRT? (We know that 1-2 years is when physical changes plateau, but we don't have a lot of good data on long term effects)
- Impact of different protocols for HRT
- The degree to which the body changes as a result of HRT
The last one is important because while there is a general finding that the skeletal features don't change significantly as a result of HRT, there are anecdotal reports from transgender women in particular of unexpected changes to height, shoe size, etc. which seem to correlate to age at which HRT was started.
Longitudinal and cross-sectional studies are needed, and these studies need to be conducted with respect to ongoing research into athletic performance. Further, such studies need to be conducted ethically, and respectfully. Transgender people should not be treated with either suspicion or as lab rats at this point.
Sports and Athlete Performance
This is another area where a whole lot of complex research is needed. We really have limited data on the "mechanics" of what aspects of the body play specific roles in a particular sport. We don't really understand much about it except in broad general terms. Longer limb length can be an advantage in some sports like swimming, but that isn't the only factor that leads towards success in the sport. There are other factors that matter significantly, including aerobic function, overall body shape (hydrodynamic efficiency), etc.
At this point in time, most sports simply lack the kind of detailed analysis and understanding to establish what traits play key roles. Even if we manage to have that kind of data, every so often an outlier case is going to emerge that shows up the underlying assumptions.
Sports and Policy
I previously wrote in some detail about the policy issues involved here. I don't think anything has occurred since then that substantially changes the issues and analysis in that piece.
The goals of public policy in sport are broadly about encouraging lifelong activity, for obvious health reasons and for socialization. Excluding transgender athletes seems to run contrary to both major aims of public sports policy. In what way does a trans woman participating in league softball (or any other sport) violate the stated aims of sport policy?
Many of the proponents of banning trans women from sport would have you believe that it is grossly unfair to have trans women competing alongside cisgender women. If it's truly "unfair" because of supposed advantages the trans woman athlete possesses, why have the people making that claim been singularly unable to demonstrate in any sport context an unfair advantage? I see lots of handwringing over "possible" advantage, yet what evidence does exist is at best tenuous in demonstrating that such advantages are real, or sustained?
A valid question does exist as to at what level of sport are we talking about things becoming "elite", and a more individual assessment becomes necessary? By assessment, I'm not talking about nonsense testing like "does this person have a Y chromosome, or the presence of an SRY gene, or whatever other methods have been proposed, but rather a thorough work-up of the candidate athlete, ranging from medical status to overall athletic performance in their chosen sport.
Websites That Track Transgender Wins
To be clear, I am well aware of a number of websites out there that record every time a trans athlete was placed in a top position at a competition. The problem with those sites is that they are little more than a record that a trans person periodically manages to win. One site in particular is problematic because they put in multiple entries for one win on the basis that "if the trans person placed 1st, then they 'stole' medals from 3 other athletes". A good day at one event (or even at multiple events) does not an advantage make.
These sites typically conflate multiple levels of sport, ranging from community level sport to elite level competition. I consider this to be a major problem with this data because there's a considerable distance between community sport and elite level sport. The goals are often dramatically different from a policy perspective.
Further, these sites do not provide us with any context about a given competition. They simply take the position that any time a transgender woman wins in competition, that it is "unfair".
Consider the following factors though:
- How many participants were in the event?
- What level of sport was this event?
- How many events take place worldwide each day?
- How many athletic events take place within a given country?
These are but a few questions that need to be answered before these websites can be taken even remotely seriously.
Discussion
Trans women have been participating in sports for a long time - and to my knowledge, none have ever even come close to "dominating" in their sport. Sure, a trans woman might win an event from time to time, but that's a far cry from demonstrating an overpowering advantage. The scientific evidence of "possible advantages" is at best limited, and does not generalize well.
While the governing bodies for sports have the difficult task of setting out the rules for their particular sports, including eligibility, the last few years has been filled with a series of whiplash-inducing changes in policy. Those changes in policy have largely been reactions to misinformation and public outcry based on that misinformation. There is a desperate need for clear, well-designed policy here.
The small numbers of transgender people on the whole mean that very few will be active in sport at any given time. It seems more than a bit of a reach to claim that transgender athletes are magically going to critically damage sport or present an "unfair" competition. Given the small numbers involved, a case-by-case approach to evaluating athletes is appropriate. Even there, I worry about this turning into a "body policing" exercise, like that which Caster Semenya has been subjected to.
I have to express my concern that the handwringing over "protecting women and girls sport" is really little more than a repackaging of 19th century misogyny where women were heavily restricted from sport "because they might hurt themselves" (and some of those justifications were just wacky). Supposing unfairness without evidence is pretty much the same thing.
When it comes to non-elite level sport, blanket bans such as that being implemented in Alberta and several US states are at best wrong-headed as they impose a collective punishment on transgender people (banning them from participation) based not on evidence, but on supposition. Kanwar (2025) points out that there are far more serious issues in women's sport than a handful of transgender women. I find it appalling that the Alberta government has chosen to continue to demonize a small group of people for political gain.
References
Fairness and Safety in Sports Act. Alberta. Retrieved from: https://docs.assembly.ab.ca/LADDAR_files/docs/bills/bill/legislature_31/session_1/20230530_bill-029.pdf
Hamilton B, Brown A, Montagner-Moraes S, et al (2024). Strength, power and aerobic capacity of transgender athletes: a cross-sectional study. British Journal of Sports Medicine 2024;58:586-597. Retrieved from: https://bjsm.bmj.com/content/58/11/586
Human Rights Watch (July 15, 2025). Global: Caster Semenya’s Court Victory a Win for All Athletes. Retrieved from: https://www.hrw.org/news/2025/07/15/global-caster-semenyas-court-victory-a-win-for-all-athletes
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