Miroslav Imbrišević
Heythrop College, University of London
Sharron Davies, a former Olympic swimmer, recently said that transgender athletes competing in the female category have a competitive advantage because they were born male. Some in the transgender community condemned these comments as transphobic. Do transgender women athletes have an unfair competitive advantage when competing in female categories? The fear around discussing this topic probably explains why only retired British athletes supported Davies publicly, while currently active competitors remained silent. (Note that I will focus exclusively on transgender women here, ignoring the subject of intersex athletes.)
Female to male transgender athletes are free to compete without restrictions in the male category according to IOC rules. Nobody gets excited about this because there doesn’t appear to be an advantage for someone who was born with a female body and, after declaring a change of gender, wants to compete against males. They would actually be permitted to increase their testosterone levels. A bizarre case is that of high school student Mack Beggs, a transgender boy, who was forced to wrestle in the girls’ division in 2017 and 2018 because Texas required athletes to compete according the stated sex on their birth certificate. Questions of fairness were raised because Mack was transitioning and received low doses of testosterone. Now that he has entered college, the rules are different and he can wrestle for the men’s team.
Does the male physiology of transgender women affect the fairness of competition in female categories? When it comes to creating fair conditions of competition between transgender women and natal women, the IOC and the IAAF focus on testosterone levels. This is taken to be the marker for effective advantage in competition. But the prescribed testosterone levels disadvantage natal women. Alison Heather, professor of physiology at the University of Otago, criticised the IOC for allowing weightlifter Laurel Hubbard to compete in the female category. Previously Hubbard competed as a male. Heather stated that a natal woman is unlikely to reach the testosterone level of 10 nanomoles per litre (the maximum allowed under IOC rules). The average level for females is at 2.8 nmoles/L and the average for males is 23-25 nmoles/L. This means that Hubbard, and any other transgender woman, could compete with testosterone levels which are up to three times higher than their female competitors. Note that in 2018 the IAAF reduced the permitted levels to 5 nmoles/L.
Legacy effects
Apart from testosterone levels, there are other competitive advantages trans women may have over a female. We need to consider the ‘legacy effects’ of having been born with a male body (larger heart and lungs, higher bone density and the issue of muscle memory among others). John Brewer, professor of applied sport science at St Mary’s University, stated recently: “So, inevitably, when you go into high-performance sport, where the difference between success and failure is quite small, that ‘legacy physiology’ alongside the muscle growth testosterone creates will give, almost inevitably, transgender athletes/individuals a physiological and indeed a performance advantage.”
There is comparatively little research about the performance of transgender athletes. In one study by Gooren & Bunck from 2004 the subjects were not athletes. The study analysed the effects of androgen deprivation (19 M-F subjects) and androgen administration (17 F-M subjects) on muscle mass, haemoglobin (Hb) and insulin-like growth factor-1 (IGF-1).The authors conclude that F-M athletes would probably not have an unfair advantage. But the results for M-F subjects are not conclusive either way. One finding from the study needs highlighting (2004;425): “Androgen deprivation of M-F decreased muscle mass, increasing the overlap with untreated F-M, but mean muscle mass remained significantly higher in M-F than in [untreated] F-M.” I conclude that the significantly higher muscle mass would give transgender women athletes an advantage in certain disciplines.
Physical differences
The first study of trans women athletes is by Joanna Harper (2015). Harper, a trans woman and long-distance runner herself, studied 8 non-elite long-distance runners and found that their performance before hormone suppression more or less matched their performance after HRT, when using age as a measure. For many of the subjects there were long gaps in competing before and after testosterone suppression (the longest being 29 years). This required age grading (Grubb) as a method of comparing the performance of athletes.

Harper (2015) writes: “It should be noted that these results are only valid for distance running. Transgender women are taller and larger, on average, than 46,XX women (Gooren and Bunck, 2004, 425-429), and these differences probably would result in performance advantages in events in which height and strength are obvious precursors to success – events such as the shot put and the high jump. Conversely, transgender women will probably have a notable disadvantage in sports such as gymnastics, where greater size is an impediment to optimal performance.”
Harper (p. 7) admits: “It is significant to note that none of the eight subjects was a truly elite runner. An optimal study would use world-class runners and the results could be used to justify the presence of transgender women in events such as the Olympic Games.” And she concludes: “As such, the study cannot, unequivocally, state that it is fair to allow to transgender women to compete against 46,XX women in all sports, although the study does make a powerful statement in favour of such a position.”
Harper (p. 7) also comments on the extra muscle mass, noted by Gooren & Buck (2004): “This extra muscle mass might cause increased speed when compared to cisgender women, and hence faster times and higher AGs at shorter distances. Increased muscle mass and heavier bones are not conducive to long distance running, and would actually be a disadvantage when running distances of a half marathon and higher, causing slower times and lower AGs.”
Oddly, Harper notes that the following trans women athletes were not particularly successful in their disciplines: Renée Richards (tennis); Lana Lawless (golf); Natalie Van Gogh, Michelle Dumaresq, and Kristin Worley (cycling); Fallon Fox (martial arts). But when you look at the stats of these athletes Harper’s assessment appears to understate their successes.
In 2016 Harper et al.present a study of 6 elite transgender women athletes, and come to similar conclusions. The subjects were one sprinter, one rower, one cyclist, and three distance runners. The largest time lapse between measured performances was 18 years. Even with age-grading I am concerned about these long time lapses between measurements. After all, we want to know how elite athletes perform immediately after they transition in their prime (once they are eligible for competition). Furthermore, Harper’s data sets in both studies are – understandably – small.
Another study from 2015 examined the preservation of volumetric bone density and geometry in 49 trans women (male-to-female) before and after 1 and 2 years of cross-sex hormonal therapy (CSH). The authors concluded that “their skeletal status is well preserved during CSH treatment, despite of substantial muscle loss.”
The latest study (2018) assesses muscle strength after hormone treatment. The authors conclude: “1 year of cross-sex hormone treatment results in increased muscle strength in transmen. However, transwomen maintain their strength levels throughout the treatment period. We conclude that the altered sex hormone pattern induced by gender-affirming treatment differentially affect muscle strength in transmen vs. transwomen.”
Safety issues
My discussion so far suggests that transgender women may well have an advantage when competing against natal women, but this may differ according to discipline. It follows that raising the issue or questioning the fairness of such competitions is not transphobic per se.
There is also the issue of safety of the competitors to be considered, particularly in martial arts, but presumably also in contact sports like Roller Derby. A transgender woman competing in martial arts or boxing events is likely to inflict more damage than a natal woman because of their physiological legacy.
If we look at the difference between male and female world records we notice a 10-11% performance gap in the running disciplines – in favour of the male athletes. In other disciplines the difference in performance is even greater: High Jump (17%), Long Jump (19%), Triple Jump (18%), Pole Vault (21%). Andrew Langford, from Sheffield Hallam University, explains that “within male competition, the world’s best performances by different individuals often fall within 1 percent of each other, sometimes even within 0.1 percent. The same is true of female competition.” Testosterone suppression in transgender women athletes aims to bring their levels down, but it doesn’t mitigate for the effects of their male physiology.
When it comes to high school athletics, 17 states in the US only require self-ID in order to compete as a female athlete.As long as governing bodies focus on testosterone levels as the only relevant performance advantage, transgender athletes (who fall within the permitted testosterone levels) have a right to compete, and claims of cheating are misguided. After all, they are abiding by the rules. When it comes to high school athletics, 17 states in the US only require self-ID in order to compete as a female athlete. In these competitions neither the testosterone levels nor the legacy physiology of transgender athletes matter. This of course disadvantages young female athletes.
We need to ask: is a competitive advantage also an unfair advantage? There is rarely perfect equality between the competitors within the sex categories ‘male’ and ‘female’. The swimmer Michael Phelps has a long and powerful torso that is wholly disproportionate to his height, as well as disproportionally short legs, and he produces less than half of lactic acid than his competitors, etc. There is always some form of inequality in competition that is based on natural ‘endowments’ – and this is something we have always accepted.
Trans athletes/activists point to these variations in competitive advantage within sex categories and argue that, even if there were an advantage by male to female (M-F) trans athletes, in spite of the required testosterone suppression, then we should simply accommodate these athletes, just as we accept Phelps’ advantages. The problem with this claim is that traditionally we don’t categorise swimmers by height, arm length or feet size; within some disciplines we categorise by weight (boxing, martial arts, weight lifting). But in general, we class competitors by sex (sailing and equestrianism are exceptions – here physical power is not central). The logic of the above defence is faulty: we cannot view the competitive advantages of trans women athletes as merely variations within a sex category. If we did so we would admit an athlete with the biological advantages of one sex to compete in another sex category. We are not simply adding another variation within a sex category, we are effectively admitting a person, who benefits from having been born male-bodied, to compete in the female category.
Not every right is a human right
If the differences between men and women in elite performance were marginal (say 1% or less, as they presently are within many disciplines), then we could give up the division of competition by sex categories; everyone could compete in one category, including transgender women. But as long as we have significant differences in performance between natal men and women (10% or more), this solution would be unfair to natal women – they would never make it to the podium. It still makes sense to make a distinction between male and female competitors for most disciplines. Whether in elite competition, in college or in high school, transgender women athletes may well have a competitive advantage, which might also be an unfair advantage, depending on the discipline and on the level of prescribed mitigation.
The sports philosopher John W. Devine argues that we need to tailor the eligibility criteria to specific disciplines: “While testosterone level may be one important determinant of performance in strength-based events (FN), it may be relatively unimportant in events that place less emphasis on strength and perhaps more on flexibility or stamina. Consequently, different criteria may be applicable to ensuring fair competition between trans and cis women in different sports.” Scientists call for more research in this area, so that we get a better idea about legacy physiology and competitive advantage.
Does our aspiration for inclusivity in sport override concerns about having an unfair advantage? Only if we value the good of inclusivity higher than the good of fair competition. Philosopher and cyclist Rachel McKinnon dismisses the unfair advantage issue: “Focusing on performance advantage is largely irrelevant because this is a rights issue. We shouldn’t be worried about trans people taking over the Olympics. We should be worried about their fairness and human rights instead.”

It is noticeable that there is an inflationary use of the term ‘human right’ in public discourse today. Not every right is a ‘human’ right. For a goat shepherd in the Dolomites a right (or lack of a right) to physical activity may be redundant – she gets plenty of that. But a right not to be enslaved is a human right; it is universal and based on human dignity. And this human right (not being violated) will be important and valuable to the goat shepherd.
UNESCO (2015;1.1) declared: “Every human being has a fundamental right to physical education, physical activity and sport without discrimination on the basis of ethnicity, gender, sexual orientation, language, religion, political or other opinion, national or social origin, property or any other basis.” The adjective “fundamental” strikes me as hyperbolic – think of our goat shepherd. Note also that trans athletes are not barred from competing any more. However, biological males don’t have an unqualified right to compete in another gender. At present the IOC and IAAF require some form of mitigation for presumed competitive advantages (via testosterone suppression). McKinnon appears to demand an unqualified right to compete in whichever category the trans athlete desires. But absolute rights are rare. The right not to be tortured or enslaved are prime examples – and these are “human” rights.
UNESCO declared that we have a “fundamental” right (rather than a “human” right) to physical activity without being discriminated on the basis of irrelevant criteria – e.g. hair colour or skin colour. Previously women were excluded from track and field events at the Olympics – this was unjust, because being female is not a relevant criterion for exclusion from sporting events. However, it is just to discriminate on the basis of relevant criteria (e.g. testosterone levels); and this is what sports governing bodies are doing.
Do transgender athletes have an unqualified right to compete in the (sex) category that conforms to their gender identity as claimed by McKinnon? Perhaps, but first we would have to dismantle the difference between biological sex (material reality) and gender (socially determined/psychological reality). And some trans women subscribe to both propositions: that their gender is ‘woman’, and their sex is ‘female’. If the latter were true, then trans women could freely compete in the female categories – and testosterone suppression would not be necessary. But this is the point Sharron Davies tried to make: in sport we cannot ignore that there is a difference between biological sex and gender, and if we do, we lose fairness in competition.
The law, and legal fiction
For various reasons the law sometimes relies on legal fictions. In company law, for example, we treat a corporation (in some respects) as if it were a natural person. Transgender legislation in the UK has also created a legal fiction to help people suffering from gender dysphoria, so that their lives may go better. The UK Gender Recognition Act 2004 states: “Where a full gender recognition certificate is issued to a person, the person’s gender becomes for all purposes the acquired gender (so that, if the acquired gender is the male gender, the person’s sex becomes that of a man and, if it is the female gender, the person’s sex becomes that of a woman).” The claim that a transgender woman’s (biological) sex is female is such a legal fiction.
Unfortunately, this can have detrimental consequences for natal women, which has been recognised in later legislation. Trans women can be excluded from female-only spaces. Here is an example from the Explanatory Notes to the UK Equality Act 2010 (p. 157): “A group counselling session is provided for female victims of sexual assault. The organisers do not allow transsexual people to attend as they judge that the clients who attend the group session are unlikely to do so if a male-to-female transsexual person was also there. This would be lawful.”
This example illustrates that there can be good reasons to exclude transgender women from female-only spaces. In sports, permitting unqualified eligibility for transgender women in female events would result in trans athletes dominating sports and displacing natal women from podium places. The experience of being pushed aside by male(-bodied) persons is all too common for natal women – this is why we have created female-only spaces (and sex categories in sport). The aim of preventing such a displacement of natal women in sport, because it is based on unfair competitive advantages, would be a good reason to exclude transgender women or to qualify their eligibility in female events.
I have two answers to my original question. Either we mitigate for the advantages of transgender athletes (including their legacy physiology), and tailor the mitigation to the respective disciplines (after thorough research), or we create separate categories of competition for transgender athletes. In this way we could maintain fairness in competition for natal women.
Let me finish with a remark about the tone of the debate. Philosophers are trained to examine the argument rather than attacking the person who put forward the argument. This principle should guide the debate and would stop things from turning toxic when discussing transgender issues.
Copyright © Miroslav Imbrišević 2019