Sex Isn’t Binary, But Sports Competition Is: A Defense of IAAF’s Policy

Gender is irrelevant in sports, but the male-female sex dichotomy between competitors serves to allow females to compete and participate in elite competitions as well as males.

By Callie Burt

Robust public criticism has accompanied the new regulations of IAAF, the world athletics governing body, which set a maximum limit for testosterone levels among middle-range distance runners in the female classification, such as the highly successful and much debated Olympian Caster Semenya. This new policy has been met with much vituperation, and critics have bemoaned its unfairness, and even “absurdity”, in ignoring the real complexity around these issues. I offer a contrarian view rooted in the notion of sex segregation as non-arbitrary and justifiable and gender as irrelevant. To foreshadow the foregoing, the sex segregation of sports relies on a sex binary that does not exist, leaving the IAAF in an impossible situation, having to demarcate the boundary between “male” and “female” for competition. I argue that in contrast to the current situation, which allows individuals to sort themselves into sex categories for competitions (by using gender identity or sex assignment at birth), the new IAAF policy relies on a biological marker (i.e. sex hormones), which undergird the sex separation of sports competitions. Though this marker is certainly not perfect, it is defensible in practice and purpose. I defend the aim of this policy here, even as I leave aside the specific level of testosterone specified in the new policy.

Rationale and Persistence of Sex Separation

Sports have long been sex-segregated for the simple reason that, otherwise, males would dominate women in most competitions. Specifically, the IAAF “divides competition into male and female classifications because male athletes have clear performance advantages in terms of size, strength, and power, as a result – in particular – of increased lean body mass and increased serum haemoglobin, which in turn is mainly due to the fact that, starting from puberty, they produce 10‐30 times more testosterone than women.” Although levels vary based on a number of factors including age, the “normal adult female” range is from roughly 10 to 50 ng/DL and 300 to 1100ng/dL for “normal adult males”.


Given that this classification has persisted over time, societies have seemingly agreed that sports involvement and competition, which includes the chance of winning and a professional career, is valuable for both females and males. To be sure, one might argue that other criteria should be used for segregating sports—but I will leave that aside for now. At present, we do separate sports competition by sex due to biological advantages of male athletes, and this practice is not being debated. Females compete with females, males compete with males, and this holds for many sports including the track and field middle-range distances at the center of recent debates.

Sex Is Not Binary

This all seems relatively straightforward and uncomplicated; sports competitions are separated into male and female groups. However, biological sex isn’t dichotomous (as Anne Fausto-Sterling articulated in her widely-read 1993 article). Despite what many of us learned in high school, the world does not consist merely of XX or XY humans who appear, present, and grow up to be females and males, respectively, with unalterable, genetically determined “normal” sex development. Indeed, at present, academic sexologists typically differentiate between chromosomal sex, gonadal sex, hormonal sex, and genital sex. To be sure, most (99%) of the time, individuals can be classified as male or female with matching chromosomes, hormones, gonads, and genitalia. Such individuals can be facilely classified as “male” or “female” for sports. For, those who do not “match” or whose sex development does not correspond to the “normal” sex developmental pattern, sports classification becomes convoluted. We have to classify individuals into “male” and “female” categories, despite the fact that many people exist in between (rough estimates are 1 out of every 1000, but this could be an underestimate). The problem is figuring out how; ideally some scientific consensus would exist, but the only scientific consensus that exists suggests that sex is not and cannot be understood as a binary.

Creating a Binary for Sports Competition

One way to deal with this situation is not to regulate it at all. Critics of the IAAF policy seem to agree with this (non-)policy, implying that sex assignment (presumably at birth) and/or legal identity should be the determining factor for sports classification. Indeed, an author of a recent NYT piece (Dreger) suggested that doing otherwise is unambiguously wrong, or “cruel and absurd”. But is it and, if so, why?

Michael Phelps, Olympic swimmer. Source: CNN

In my view, it is not unambiguously wrongheaded, and no proponent of this (non-)policy justifies their position adequately. Not that they haven’t tried; a few have. For example, one attempt at justification using the rationale of “inclusion” and natural biological differences uses the analogy of Michael Phelps’s wingspan. They argue most amazingly successful athletes, such as Phelps, have unusual (as outside of the normal range) biological characteristics which give them a significant advantage in sports competition, and that limiting natural testosterone levels for participation in the female category is akin to limiting the wingspan of swimmers, which is patently absurd. But it isn’t akin to that at all. While I do recognize that most elite athletes have biological features that confer advantages, this analogy is not appropriate because sports are not segregated by wingspan. This wingspan analogy fails as a critique of the processes used to classify individuals into sex categories, and it is these processes that are at issue here.

Although I acknowledge the complexity of this issue and the fact that any solution is going to disadvantage some individuals, adopting an identity or assignment classification that is unmoored from the biological factors underlying the sex-segregation is nonsensical. If we are going to continue to separate competitions by sex, then allowing individuals such as Semenya who have intersex conditions or DSD, with levels of testosterone that are several (apparently 5-10) times greater than the upper normal level for adult females is inconsistent with the rationale of separate competitions and, in my opinion, cannot and has not been justified, and most certainly not merely by claiming the value of inclusion or tolerance.

But, inclusion!

Diversity and inclusion are progressive leitmotifs of this era, and values I support wholeheartedly. However, we cannot have both inclusion and a female category; the female category is a protected category that is purposely exclusionary. “Inclusion”—as the IAAF policy critics would have it—comes at the expense of the “protected” category created to allow females to compete at elite levels, which would not be possible without a female category,  largely as a consequence of the actions of testosterone. Importantly, testosterone’s effects are not merely short-acting but, instead, have developmental effects that shape muscle mass, fat production, and red blood cells (Storer et al. 2003; Woodhouse et al. 2002; Herbst & Bhasin 2004). There is a reason it is a drug of abuse by athletes and that its exogenous use is banned: it confers a significant competitive advantage.

As long as we separate competitive sports by sex, we have to draw a line somewhere on the boundary between “male” and “female” among those <1% who do not fall neatly in these categories. The IAAF has been put in a difficult situation (drawing that line), and the new line is seemingly quite fair. No one is “excluded” from sports competition, but to be included in a protected category when one lies in between, one has to possess the biological indicators that at least approach levels of those who fall into the protected category. Indeed, individuals can still have more than double the level of the high range of “normal adult females” and be eligible for competition under this new policy. Moreover, as the IAAF notes, they are not attempting to adjudicate one’s “actual sex” nor do they address issues of gender; rather, they are determining who is eligible for the “female class” as a protected category.

Are We Really Just Reifying Gender Norms?

As another attempt at justification, Dreger stated: “It’s worth noting that men who naturally make extraordinarily high levels of testosterone are allowed to play without question. Additionally, the World Anti-Doping Agency, which regulates doping in sports, allows men who can prove they have naturally low levels of testosterone to take testosterone supplementation without considering it doping. So how is this just about natural hormone levels and fairness — and not actually about cultural norms of sex and gender? Elite sports agencies also allow non-intersex women to manipulate their hormones, through birth control pills, to ensure that they are at the most advantageous part of the menstrual cycle when they compete. That’s considered fair. But women born with differences of sex development [DSD] are subject to a whole different set of principles. For them, natural advantage is considered unfair, and unlimited testosterone is understood to be something men get to enjoy, even though all women also make it naturally.”

While this may sound damning for the IAAF policy, I argue that is only because Dreger is using gender and sex interchangeably and ignoring the fact that intersex individuals do not fit neatly into the sex binary used to separate competitors. Phrased alternatively it doesn’t sound problematic at all: men who fall below the normal range of T levels (still far above the maximum range allowed for women, and likely well below that for women such as Semenya) can have medical testosterone supplementation for life purposes; women can take birth control. These examples don’t challenge the sex dichotomy for competition; if anything, they reify it. No matter how we look at the situation, no matter how much we want to be fair to everyone, one cannot simply justify—in a manner consistent with the rationale of separate competitions—allowing individuals to use sex assignments at birth or gender identity to classify themselves into competitive categories because separate categories were created due to physiological differences; not gender, not identity, not norms, and not presentation. These are biological advantages, not social ones. Gender is irrelevant.

This issue of sex as biology versus gender as identity or presentation becomes especially important when considering the inclusion of transgender individuals in sports competitions. Let me be clear: I fully support the rights of individuals to live as men, women, non-binary, queer, or whatever they feel is their essence or their self. But to repeat likely ad nauseam, sports are sex, not gender, segregated due to physiological differences which greatly advantage natal males, those who go through puberty with male hormones, and those who currently have ‘male physiology’. How one presents and identifies is irrelevant to the segregation of sports and, given biological differences, this is for a specific, and I believe good, reason. We have chosen to draw a line to allow females to compete with each other and experience the rewarding, learning, and challenging aspects of sports and winning—which most would not be able to experience without such sex separation. Until we draw the line elsewhere or get rid of the line entirely, competing in the male category should be the default (whether one is (cis)male, trans, intersex/DSD with higher T levels than allowed—again several times higher than the high end of the normal range for “adult females”).

Indeed, if I was finding fault with the IAAF policy, I would suggest that, first, it is too lenient, and, second, we should change the names of the groups to make it clear that the policies are (as the IAAF stated) “in no way intended as any kind of judgment on, or questioning of, the sex or the gender identity of any athlete.” I suggest the creation of a “protected” category and a mens+, general, or open category. Anyone can compete in the general open category, but only natal females who have experienced development without high levels of testosterone due to intersex conditions, hyperandrogenism, and/or transgender status can participate in the “protected category.”

Socially-Created Binaries Are Ubiquitous and Necessary

Before concluding, it is worth recognizing that collapsing continuous or non-binary categorizations into dichotomous ones is quite common in our society. Age restrictions are one example. We have dichotomized age for the ability to purchase alcohol; for senior citizen status; and create age categories for various competitions; yet, we all know that there is no qualitative shift between age 20 and 364 days and age 21, between 64 and 65, and so on. Similarly, we create speed limits for roads that vary widely in characteristics that usually range in 10mph increments. In the medical field, diagnoses reflect socially-created qualitative cleavages of underlying continuous characteristics that mark “health” from “problem” or “disorder”; for example, one moves from “normal weight” to the “overweight” category at 24.9 to 25.0 BMI; from normal blood pressure to “prehypertension” at 120 to 121 systolic; and I could go on. Perhaps less obviously, we do this same thing for racial status, which itself reflects a continuum of influences shaped by individuals’ multitude of ancestors. We are constantly dichotomizing underlying continuous or ordered realities into binaries for a variety of purposes. Seen in this light, sex separation of sports isn’t all that different. But we have to draw the line somewhere.

Perhaps soon we may choose to create new categories that provide more options for those who do not fit the sex binary, and maybe we will decide to end sex segregation of sports entirely, which would, I believe, be detrimental to many females, but may be addressable in some other fashion (height? Weight? Muscle mass?). But, for now as currently constituted with the rationale to allow females to compete with other females who have experienced female-developmental processes, placing a reasonable upper limit as the IAAF have done on the levels of testosterone—again several times higher than the upper range considered normal for adult females—is a better option than the current (non-)policy. Certainly, this policy will pose a hardship for a relatively small number of hyperandrogenic, DSD, or intersex women, and that is really unfortunate. In the current situation, a few will either have to choose medical intervention to lower testosterone, change categories, or decide to not compete at elite levels. This is one of those complex situations where no policy can serve everyone’s needs and desires. This new IAAF policy, however, does rationally and carefully attempt to provide the most fairness for the greatest number recognizing the goals and the purposes of the separation of sports competition by sex. For now, this is better than nothing.


Dreger, Alice. “Track’s Absurd new rules for women.” The New York Times, April 27, 2018.

Storer, Thomas W., Lynne Magliano, Linda Woodhouse, Martin L. Lee, Connie Dzekov, Jeanne Dzekov, Richard Casaburi, and Shalender Bhasin. “Testosterone dose-dependently increases maximal voluntary strength and leg power, but does not affect fatigability or specific tension.” The Journal of Clinical Endocrinology & Metabolism 88, no. 4 (2003): 1478-1485.

Woodhouse, Linda J., Nidhi Gupta, Meenakshi Bhasin, Atam B. Singh, Robert Ross, Jeffrey Phillips, and Shalender Bhasin. “Dose-dependent effects of testosterone on regional adipose tissue distribution in healthy young men.” The Journal of Clinical Endocrinology & Metabolism 89, no. 2 (2004): 718-726.

Herbst, Karen L., and Shalender Bhasin. “Testosterone action on skeletal muscle.” Current Opinion in Clinical Nutrition & Metabolic Care 7, no. 3 (2004): 271-277.

1 Comment

  1. Well reasoned.I agree that essentially dual sexed people shouldn’t be competing against females.
    There could be a possibility of creating a category in the special Olympics for people like Semenya.However such individuals may be accommodated in competitive sports,they shouldn’t be allowed in the female category due to the ease of competition or social identity.
    If you’re going to allow abnormally high levels of Test in women’s sports,you may have a harder time justifying doping controls.I’m not naive.I’ve followed bodybuilding for many years,and there is no doubt how much hormones impact body development.
    Recently in the World Weightlifting Championships a trans MTF came in second in the open Women’s category.Not fair to the other competitors.The gold was won by a naturally large,and strong women who does have higher androgen levels due to PCOS,Sarah Robles.But my personal opinion is Sarah is clearly female.I don’t know what her hormone levels would be.But I think some variance between females is one thing,being born male another.Of course people’s body size can vary a great deal,and test isn’t the only reason why.( Myostatin levels would be one thing ) There are many sports that do have weight categories to create greater fairness,and opportunity.So male athletes do have protections in some cases too.
    I think it’s important for people to support female athletes and preserve their right to fair competition among their own human type.I just hope people aren’t blinded by political sloganeering,and afraid to speak up.
    Thank you.

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