An Executive Order and Testosterone

This is part 1 of a series focusing on transgender women in sport. An executive order and the stickiness of testosterone.

According to my Twitter feed, we live in a time where systemic injustices abound and are said to require convoluted societal re-engineering to correct. Interestingly, the same individuals discovering injustices around every corner, also act as if complex and stubborn disparities produced by biological systems can be eliminated with a nod from a physician. Fortunately for the rest of us, biological maturation produces many persistent characteristics. Enter executive orders, the transgender sport debate, and the source of all evil, testosterone.

Before we dive in, I need to clarify a couple of items. Some of you reading this are familiar with the terminology used to describe different gender identities; others are not. When distinguishing between sex and gender, unless quoting another source, I will try to limit myself to the four terms listed and defined below. This is important because in our current environment, words have suddenly come to mean anything one wants them to mean. I have also written this piece hoping lay and technical audiences can easily understand it. Ok, let’s get into it.

  • female = biological female (XX)
  • male = biological male (XY)
  • transgender woman = biological male (XY) identifying as a woman
  • transgender man = biological female (XX) identifying as a man

Biden’s Executive Order

On January 20, 2021, President Biden threw fuel on the fiery debate related to transgender sport participation when he issued an Executive Order (EO) on Preventing and Combating Discrimination on the Basis of Gender Identity or Sexual Orientation [1]. Given that we can interpret several elements within in the EO a variety of ways, it is still too early to say how this EO will be implemented (a little more on this later). Despite the uncertainty, this EO served as the impetus for a slew of articles critical of the EO [2,3,4]. These articles suggest the EO will, among other things, eviscerate women’s sport. Do many of these articles misrepresent the EO? Probably. Does this EO “eviscerate” women’s sport? Probably not. However, the EO opens the door for serious and further widespread problems in women’s sport.

Prior to diving into a couple of EO related details, it is important to frame its relevance. This EO has the potential to embed any resulting policy into a variety of institutions, particularly those that accept federal funds. Given that many educational institutions rely heavily on federal funds, and in our infinite wisdom we have coupled much of our sanctioned competitive sport to institutions of miseducation, the EO will probably influence sport. As you will see shortly, because of the equivocal nature of the EO, how the EO will affect institutions and sport remains unclear. Of course the EO means to address a myriad of scenarios, but only sport is considered here. Additionally, almost all transgender sport discussions have focused on women’s sport for obvious reasons, and I will try to aim most of the discussion in that direction.

While I cover a small section of the EO here, the EO is pretty short if you fancy giving it a read. The segment I will focus on is from Section 1. This section provides direction for the policy of the EO and includes a couple of key sentences that can and have been interpreted several ways; here are those sentences [1].

“Children should be able to learn without worrying about whether they will be denied access to the restroom, the locker room, or school sports. Adults should be able to earn a living and pursue a vocation knowing that they will not be fired, demoted, or mistreated because of whom they go home to or because how they dress does not conform to sex-based stereotypes.”

However reasonable these statements may seem, interpreting them may lead to benign or pernicious consequences. For instance, should this be taken to mean that trans children must not be denied access to restrooms, locker rooms or school sports? Or, should this be taken to mean that trans children must not be denied access to restrooms, locker rooms or school sports consistent with how they identify? Does denying trans adults the ability to participate in college sport classify as mistreatment? Or, does denying trans adults the ability to participate in college sport consistent with how they identify classify as mistreatment? These are all reasonable interpretations of the EO, but ultimately lead to disparate outcomes when implemented. Unfortunately, the ambiguity of this EO is likely a feature and not a bug.

Enforcing the EO

Upon issuing this EO, the Biden administration also gave the heads of agencies charged with enforcing the EO, 100 days to develop a plan to carry out the actions described therein. Given the vague statements of the EO, how agency heads and attorneys will interpret the EO is currently unknown [5]. They could, as alluded to above, “across the board” try to force institutions to allow transgender women to compete with/against females. A “hybrid” approach similar to current National Collegiate Athletic Association (NCAA) policy is also one of several other options. As described below, the NCAA allows transgender women to compete on a female team only after completing one calendar year of testosterone suppression treatment [6]. How enforcement of the EO plays out at different institutions is anyone’s guess. It is also unclear if/how criteria will differ across levels of sport (high school, college, etc.). Time will tell.

One Hormone to Rule Them All

Many sporting organizations have drafted policies that regulate transgender sport participation. Though it is beyond this article to address all the various approaches, two well-known organizations, the NCAA and International Olympic Committee (IOC), focus their regulation almost entirely on a single variable. What is that single variable? Good ole testosterone, the harbinger of toxic masculinity.

Despite its naysayers, testosterone confers countless physiological and psychological benefits on athletes. It is no accident that most sporting organizations ban and test for anabolic drugs. It is also no accident that the NCAA and IOC have focused on testosterone in their regulation of transgender athletes. These organizations clearly recognize the advantages males have over females in most sport, but also allow trans women to compete in sport consistent with how they identify. However, of the many genetic disparities between males and females that differentiate sport performance, testosterone (and other hormones) is perhaps the only variable that can be easily manipulated. The ergogenic nature of testosterone and the relative ease with which testosterone is manipulated, make it a perfect target for policy. My focus here relates to the reality that the NCAA, IOC and many “talking heads” do not fully appreciate the permanence of the countless adaptations testosterone bestows upon its hosts. Or, perhaps the NCAA and IOC recognize this reality, but other forces or outcomes motivate their decisions. In future articles I may tackle the arguments questioning the abundant benefits of testosterone, genetic differences between sexes that influence sport independent of testosterone and the motivations behind the transgender policies of organizations such as the NCAA and IOC; but not today my friends.

Fortunately for us, a couple of recent reviews [7,8] do an excellent job of detailing the many performance oriented sex differences and changes that result from the suppression of testosterone during transition. If you are like this fella and doubt the veracity of the science related to transgender individuals and athletes, sex differences in sport, or the advantages testosterone provides males, please stop here and read those reviews. Both reviews are free and open access so you open science zealots will be pleased. Anyway, I will focus on a few items that I feel best highlight the error of using testosterone suppression as the gatekeeper deciding whether transgender women can participate in sport with females.

But first, let’s pick on the NCAA for a moment and address how the organization justifies allowing transgender women, after a year of testosterone suppression, to compete with females. The NCAA issued its original guidance on transgender athletes in 2011 and, to my knowledge, has remained more-or-less unchanged. I should also note that the IOC adopted the same one-year policy of the NCAA circa 2015. The following includes three segments from the NCAA Inclusion of Transgender Student-Athletes document addressing testosterone suppression specifically [6].

Contained in the document is the following quote from Eric Vilain, M.D., Ph.D.:

“Research suggests that androgen deprivation and cross sex hormone treatment in male-to-female transsexuals reduces muscle mass; accordingly, one year of hormone therapy is an appropriate transitional time before a male-to-female student-athlete competes on a women’s team.”

A statement from the NCAA:

“It is also important to know that any strength and endurance advantages a transgender woman arguably may have as a result of her prior testosterone levels dissipate after about one year of estrogen or testosterone-suppression therapy.”

And finally, the actual policy of the NCAA that cites a single paper [9]:

“A trans female (MTF) student-athlete being treated with testosterone suppression medication for Gender Identity Disorder or gender dysphoria and/or Transsexualism, for the purposes of NCAA competition may continue to compete on a men’s team but may not compete on a women’s team without changing it to a mixed team status until completing one calendar year of testosterone suppression treatment.”

As far as I can tell, the only study the NCAA uses to support the “one year is sufficient” claim, is a 2004 study titled, Transsexuals and competitive sports [9]. This is interesting for several reasons. First, despite citing this retrospective study to support NCAA policy, the study found that muscle area was statistically higher in transgender women/biological males (n = 19) after 12 months of hormone therapy when compared to transgender males/biological females (n = 17) before hormone therapy. While policy should not be drafted based on this single study, considering the results, any policy developed should have concluded the opposite; one year of testosterone suppression does NOT eliminate the differences between males and females. In fact, in a review by Hilton and Lundberg [8], which is one of the two reviews I recommended earlier, they cite the same study as the NCAA but in support of study to support the idea that, “[one to three years of] testosterone suppression in transgender women does not reverse muscle size to female levels”. Second, in 2011 when the NCAA published its transgender policy, it clearly ignored a host of other studies that did not at the time support the policy prescription of the NCAA. Third, from 2011 to 2015 when the IOC doubled down and adopted the one-year policy of the NCAA, the body of literature grew and continues to grow to this day, in opposition to such policies [7,8]. Needless to say, the policy of the NCAA and IOC seems to reflect ideological or political leanings rather than evidence or the slightest hint of common sense.

The “Stickiness” of Testosterone

To reduce the athletic performance of transgender women to the level of females, testosterone suppression has largely focused on two outcomes. The suppression of testosterone reduces both skeletal muscle mass and hemoglobin/hematocrit. I will focus on skeletal muscle, which is most visually obvious, and may address hemoglobin at a later date.

Although performance differences have been identified between sexes prior to puberty [10,11,12,13], those discrepancies are thought to be of little consequence for sport performance. As puberty prompts teenagers to rail against authority and causes them and their parents to question each other’s sanity, testosterone remains stubbornly low in females while male testosterone surges 20x prepuberty levels resulting in male testosterone concentrations 15-fold that of females [14]. Among the performance enhancing changes caused by increasing testosterone, males gain considerably greater skeletal muscle mass than females. Of course, this is not surprising and provides males with substantial performance advantages over their female counterparts. What may come as a surprise, are the outcomes that unfold when that testosterone is “taken away”.

A substantial and growing body of evidence has provided us with a decent idea of how skeletal muscle mass changes when males undergo hormone therapy to suppress testosterone. The bulk of longitudinal evidence suggests that testosterone suppression will cause up to a 5% decrease in lean mass within 12 months and up to a 12% decrease after 3 years of suppression. If we make the wild leap and assume lean mass is related to strength, power, etc., and the typical difference between male and female muscle mass is approximately 40% [8], it can be safely concluded that 1-3 years of testosterone suppression is not sufficient to close the performance gap between males and females. This is also supported by a handful of longitudinal studies that found strength decreased only up to 7% after testosterone suppression in males [7,8]. All told, after testosterone suppression, transgender females can be expected to retain substantial performance advantages over females. This is particularly true for sports with significant anaerobic requirements where strength and power are important, which happens to be most high school, college and Olympic sport.

In addition to the countless genetic factors independent of testosterone levels during and after puberty, testosterone itself contributes to various permanent or “sticky” changes. Possibly the most pronounced and visible of these permanent adaptations, is the larger and longer bones of males resulting in part from the rush of pubescent testosterone [15,16]. The larger bones and skeletal frames of males is also associated with longer and larger skeletal muscles (more muscle mass) [17,18,19,20]. Naturally, a sizeable muscle mass advantage paired with larger skeletal size, greater height and longer limb/digit lengths, provides males and transgender females with a considerable performance edge over females. As an aside not directly related to testosterone, females also present with greater knee valgus or Q-angle, which may increase knee injury risk and reduce performance in a variety of tasks when compared to males [21,22,23]. Ultimately, these are not an inequities that can be vanquished with any duration of testosterone suppression.

Years of male typical testosterone exposure also yields other “hidden” advantages. Testosterone has long been thought to contribute to myonuclear number and may provide males with higher myonuclear density even after testosterone suppression [24,25,26,27,28]. Among other roles, myonuclei synthesize proteins that contribute to muscle size and recovery. Furthermore, skeletal muscle possesses “epigenetic memory” that allows for the maintenance and/or easier reacquisition of various muscular qualities and abilities. These include, but are not limited to, muscle size and force generation (strength) [28,29]. To form these “memories” in the first place, an individual must have previously engaged in the activities responsible for the creation of the memories. Therefore, since males have more skeletal muscle, generate higher forces and can outperform females in a variety of physical tasks, this is thought to imprint memories that advantage males and transgender women who have suppressed testosterone. Finally, directly and indirectly, males benefit athletically from a sundry of other persistent testosterone enhanced differences [30], including higher bone mineral density [18,31], elevated tendon stiffness [32,33], larger left ventricular mass [34,35] and psychological tendencies [36,37] to name a few. For those who would like “real-world” examples of transgender women competing against females, Laurel Hubbard, a weightlifter, and Veronica Ivy, a track cyclist, are both actively competing in their respective sports. Each has garnered quite a lot of media attention and like other instances, they have performed quite well and possess obvious advantages over their competitors. If you require additional visual evidence of testosterone’s life-long gifts, summon your favorite search engine and type “retired female bodybuilders”. Probably with “safe search” set to at least moderate.

Before wrapping up, let me reiterate the absurdity of using testosterone suppression to equalize sport performance between males and females. First, even if testosterone was responsible for 100% of the difference between male and female performance, after years of exposure to high levels of testosterone in males, suppression of that testosterone would not approach eliminating the performance advantage granted by testosterone. Second, sport performance is multifactorial and there are an enormous number of genetic variables that contribute to the physical advantages of males. Focusing on testosterone ignores a massive body of knowledge documenting the countless differences that create disparate outcomes between males and females. Adding insult to injury, it is difficult to imagine a scenario where the NCAA and IOC are not completely aware of the facts presented here and in countless other reports, documents, and papers. It is not as if either of these organizations are lacking access to expertise. The NCAA alone has relationships with over 1,000 universities throughout the United States, of which employ thousands of exercise and sport scientists, sport medicine physicians and other credentialed professionals that would gladly help them reason through this issue. It is fascinating these organizations run massive anti-doping programs and simultaneously, despite overwhelming evidence to the contrary, the NCAA and IOC erroneously suggest that both the magnitude and durability of male athletic advantages are washed away with a single year of testosterone suppression. Let’s hope the EO doesn’t propagate such nonsense further.

In Closing

At the time of posting this, we are roughly one month from the deadline Biden gave agency heads to have developed plans to enforce the EO. Will the EO attempt to force colleges and universities to adopt policies like that of the NCAA? Will efforts be made to require high schools to allow transgender girls and women to play on female teams? Or, will individual schools be able to continue making their own decisions? Who knows, but my guess is we can look forward to a few legal battles in the coming months and years.

Regardless of enforcement decisions, let me be clear. I do not get the impression that there will be a rush of transgender participation if enforcement decisions compel institutions to allow transgender women to compete with females. We should expect an increased number of transgender women competing with females, but a rush of participation is not my concern. It only takes one male, and that male can be a rather average male athlete, to cause significant problems. The discrepancies between males and females are so substantial, as illustrated above, that a single average male athlete can upset an entire field of individual female competitors, disrupt an important tournament, or break school records that have stood for decades. So, instead asking, “Should we allow transgender women to compete with females?” or “What is the best way to allow transgender athletes to participate as they identify?”, let me leave you with a different question.

Does it make sense to force females to compete against males? I think not.

See you in Part 2.


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