A small but growing body of research suggests that trans female athletes (born male, identifying as female) retain a significant natural advantage over their female competitors even after extended periods of synthetic hormone treatment. The findings could potentially throw a wrench in efforts by LGBTQ activists and the Biden administration to increase transgender representation in female sport leagues.

Debate has swirled for years around whether boys who assert a female identity should be permitted to compete against girls in secondary and collegiate sports divisions. Activists have argued that trans women should be treated as identical to biological women in essentially every way, including, controversially, in athletic competition.

Counterarguments, meanwhile, have held that males continue to retain marked physical advantages over female athletes, even if the former identify as girls.

The pro-transgender effort received a major boost last month from newly-sworn-in President Joe Biden, who signed an executive order on his first day in office aimed at "preventing and combating discrimination on the basis of gender identity or sexual orientation."

In that order, which cited Supreme Court precedent and federal civil rights law, Biden argued: "Children should be able to learn without worrying about whether they will be denied access to the restroom, the locker room, or school sports." The order was widely seen as an affirmation that the Biden administration would be pursuing a policy of transgender acceptance in educational environments, including sporting leagues.

Studies point to continued advantages even after hormone therapy

That males overwhelmingly tend on balance to enjoy superior athletic ability relative to females remains largely uncontested. The sport debate largely hinges on whether biological males who identify as females maintain distinct physical advantages over girls and women — particularly after extended periods on synthetic estrogen supplements — and whether permitting them to compete in women's sports puts female athletes at an unfair disadvantage.

Emerging evidence suggests that, even after significant amounts of time spent on estrogen, male athletes retain notable edges in athletic performance, potentially foreshadowing a difficult set of social and political choices in deciding whether or not transgender inclusion outweighs what may effectively function as athletic disenfranchisement for young female athletes.

One study, published in the British Journal of Sports Medicine in December, sought to "examine the effect of gender affirming hormones on athletic performance among transwomen and transmen."

Drawing on "fitness test results and medical records of 29 transmen and 46 transwomen who started gender affirming hormones while in the United States Air Force," the researchers found that "prior to gender affirming hormones, transwomen [males who identify as women] performed 31% more push-ups and 15% more sit-ups in 1 min and ran 1.5 miles 21% faster than their female counterparts."

"After 2 years of taking feminising hormones," the researchers write, "the push-up and sit-up differences disappeared but transwomen were still 12% faster."

In another study published the same month in the journal Sports Medicine, the authors sought to determine "whether evidence exists to support the assumption that testosterone suppression in transgender women removes the male performance advantage and thus delivers fair and safe competition."

The scientists found that "current evidence shows the biological advantage, most notably in terms of muscle mass and strength, conferred by male puberty and thus enjoyed by most transgender women is only minimally reduced when testosterone is suppressed as per current sporting guidelines for transgender athletes."

Noting that estrogen supplements appear to have no effect on "skeletal size and bone density," the writers point out that any advantages conferred by those attributes are unlikely to be affected by hormone treatment.

Citing research into muscle size and body mass retention during testosterone suppression, the writers also argue that "the muscle mass advantage males possess over females, and the performance implications thereof," appear to remain unaffected over the course of at least several years.

"In sports where muscle mass is important for performance," they write, "inclusion is therefore only possible if a large imbalance in fairness, and potentially safety in some sports, is to be tolerated."

'The voices of female athletes need to be heard'

Transgenderism itself has become a deeply fraught issue in modern American society. Activists have demanded the upending of deeply embedded cultural norms to accommodate trans individuals — including allowing biologically male trans females to use the bathroom and showering facilities of girls. A small but vocal network of commentators and advocates, meanwhile, has attempted to push back against that rapidly solidifying regime.

Arlette Perry, a clinical exercise psychologist at the University of Miami, argues that the data are still too sparse to make a determination one way or the other.

"I believe there is just not sufficient scientific data to say one way or the other with regard to transgender athletic competition," she said. "There are just too few transgender athletes at this time to draw any significant conclusions."

Jeremy Fransen, an assistant professor of exercise science at Aurora University, acknowledged that "there could be some physical advantages that trans women could retain that would give them an advantage in some sports some of the time."

"For example, having a larger skeletal structure and mass could be advantageous for strength sports (e.g., powerlifting)," he told Just the news, "but wouldn't be helpful for certain endurance sports (e.g., marathon)."

"Success in athletic competition is a highly complex mix of physiological and psychological components," Fransen said. "For example, you could lower the amount of testosterone (sex hormone) in trans women to that of cis women, but there are other things to consider, like the amount of free vs bound testosterone and sensitivity of muscle receptors to testosterone."

Where female-identifying male athletes have been permitted to compete in girl's leagues, the results have at times been decisive. In Connecticut several years ago, two transgender athletes allowed to compete against girls quickly broke numerous state records in the female divisions, leading to claims from numerous female athletes that they enjoyed an unfair competitive advantage due to their male bodies.

The Department of Education last year concluded that Connecticut discriminated against girls by allowing trans females to compete against them. Fransen argued that policymakers should consider female athletes' opinions when crafting transgender sports rules.

"I think the best thing from a policy standpoint is to ask female athletes, as they are the population most affected," he said. "The voice of female athletes from high school through college and professional needs to be heard."

"One solution may be to create a new transgender division in most sports," he said. "In some sports (race car driving) it may not matter at all and there is no need. Again, it's a larger discussion among the particular athletes in each sport."

'The biggest objections that I've seen are from the females'

The issue has become a flashpoint in the larger ongoing cultural battle surrounding transgenderism, a topic which includes such questions as whether or not doctors should remove healthy body parts to conform a patient's body to his or her "gender identity" and whether young children should be given synthetic hormones in accordance with their professed gender.

Transgender athletics arose in the U.S. Senate this week when Kentucky Sen. Rand Paul grilled Miguel Cardona, Joe Biden's nominee for Secretary of Education, over his position on males competing against females in school athletics.

Mostly dodging Paul's aggressive questions on the matter, Cardona ultimately said: "I think it's the legal responsibility for schools to provide opportunities for students to participate in activities, and this includes students who are transgender."

In other strata of society, the issue is at times difficult to broach. Warren Whisenant, the chair of the kinesiology and sports sciences department at the University of Miami, said that, along with racial issues, gender is one of the topics about which "students become very reluctant to speak out in class."

"To guide them through an open dialogue can be somewhat difficult at times," he said.. "The students, they don't want to be accused of being homophobic or racist."

Whisenant, who teaches a Contemporary Issues in Sport in North America class, said he has observed a "shift" in the last several years regarding transgender ideology among his students.

"Five years ago, students were absolutely against it," he said. "Now there seems to be a bit more support."

"[T]he biggest objections that I've seen from students are from the females," he added. "Girls do feel that in many instances, from a physiological standpoint, that males who haven't gone through a 'transition' process possess a competitive advantage. Those students tend to shy away from [debate].

"The males in the classes, for whatever reason, don't feel as threatened by the idea of a female who transitioned to a male," he said. "They tend to be much more accepting of the females who transition."