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Science alone can't solve fairness debate on transgender athletes, says expert endocrinologist and UW professor

Jun. 1—In recent years, debate has gripped society regarding whether it is fair to allow transgender women participate in women's sports. One University of Washington professor believes an answer to the debate cannot be found in science or simple biology.

According to Dr. Bradley Anawalt, the science of whether transgender women have an advantage in sports remains up in the air. But even if studies showed crystal-clear results, both sides of the debate would still have points to make over what kind of society we all want.

"There can be no scientific answer to what is fair. There is never going to be a perfect answer and there is always going to be some level of controversy," he said.

Anawalt is an endocrinologist and professor of medicine at the University of Washington School of Medicine. He is a member of the NCAA Committee on Competitive Safeguards and Medical Aspects of Sports and a consultant to the U.S. Anti-Doping Agency Therapeutic Use Committee.

Testosterone in the body and the long-term effects of a testosterone-based puberty are the primary drivers of men's athletic advantage in most sports, Anawalt said. But the degree by which a trans woman's medical transition can counteract that advantage is still an open question.

"The question is how long does it take for differences in strength and power to disappear," he said. "There are a limited number of studies and much remains unknown."

Dr. Kellan Baker, who leads a national organization providing health care to the LGBTQ+ community, disagreed in part. A testosterone-based puberty does not automatically make a better athlete than someone who went through an estrogen-based puberty, he said.

"The factors that influence athletic performance are incredibly varied and incredibly widely distributed. Just because some forms of athletic ability are correlated with gender — like men on average being taller than women, does not mean any one specific athlete has any particular advantage in any given sport."

"Not all men are better than all women. Not all boys are better at all sports than all girls. There is no way to point to a particular hormone or a particular experience of puberty and say this gives you unambiguous dominance in this sport. It simply doesn't work like that," he said.

What is gender-affirming care?

While not all transgender people need medical interventions as part of their gender transition, many trans women seek to suppress the testosterone in their body and replace it with estrogen. Among other effects, a transgender woman undergoing this treatment will experience breast growth, softening of skin, redistribution of fat across the body to the hips and breasts, and a decrease of testicular volume.

A big impact of feminizing hormone replacement therapy is a decrease in muscle mass and strength in the body, which are main drivers of athletic performance. Over time, estrogen therapy will bring a transgender woman's hormones in balance with that of a woman who is cisgender — a term for those who are not transgender. What remains unclear is to what degree athletic advantage remains after someone has gone through this process.

Citing a 2021 metastudy analyzing 24 studies on this subject, Anawalt said current research suggests it takes anywhere from one year to three years on feminizing hormones for muscle mass to become similar to cisgender female levels.

Other effects of a testosterone-based puberty cannot be changed. Hormone replacement therapy may affect athletic performance depending on the sport.

These physical characteristics are more likely to change if hormone replacement therapy begins before the end of puberty. Anawalt also noted advantage all but disappears if the testosterone-based puberty is prevented in the first place.

"We presume if puberty blockers prevent pubertal body changes, most if not all of the advantage would be removed," he said.

Typically at 12 years old or at the onset of puberty, puberty suppressants can be considered. These blockers are fully reversible and pause puberty development to give the transgender youth more time and maturity to make a more permanent decision. Puberty blockers also are used frequently for children whose puberty begins too early.

Transgender inclusion in sports leagues

Rules around transgender people's participation in athletic competition vary widely between sports and the level at which the games are played.

Elite-level sports typically require hormone replacement therapy for some period of time before a transgender athlete is allowed to compete.

Previous guidance at the International Olympic Committee required transfeminine competitors to have their testosterone suppressed below a certain threshold for a year prior to and during competition. In 2021, the IOC released a less restrictive framework allowing International Federations to create their own criteria.

Other sports are going in the opposite direction. In 2022, swimming's governing world body FINA banned transgender women from competing if beginning their transition after the age of 12. The focus on transgender individuals in sports even has spread to competition not based on athletic ability. Earlier this year FIDE, the world chess governing body, banned transgender women from competing in official women's chess tournaments pending further investigation of the body.

What about in Washington?

Rules also vary at the high school and junior high levels. Some states like Idaho have attempted to ban transgender participation in school sports. Others like Washington allow transgender athletes to compete regardless of their testosterone levels or pubertal development.

"All students have the opportunity to participate in WIAA athletics and/or activities in a manner that is consistent with their gender identity," reads the 2023-24 Washington Interscholastic Activities Association handbook.

In the WIAA's Gender Diverse Youth Sport Inclusivity Toolkit, the organization says the inclusion of transfeminine athletes "has not been shown to diminish opportunities for others."

"As we celebrate the exceptional athleticism of any female athlete as they dominate and add to their sport, so too can we embrace the talents that any trans female athlete might bring. The cultivation and celebration of the athleticism of all athletes, including trans athletes, is a valuable part of any team's culture," reads the toolkit meant to guide educators and school coaches.

The toolkit also states that while some transgender athletes may have an athletic advantage over their peers, advantages in athletics because of physical characteristics are inherent to physical sports.

"The athleticism of any female athlete, as we know, can vary widely from that of other peers. Height, musculature, build, and weight are a few variables that impact performance," it reads. "Additional factors that contribute to a potential advantage include access to skills-building opportunities at earlier ages, access to facilities and coaching, greater funding for programs and teams in certain privileged communities, chronological age, birth order, and more. For these, and other reasons, some athletes have advantages and opportunities over others."

Baker agreed with the policy — stating athletic competition at that age should be focused on "life lessons like teamwork, leadership, and sportsmanship" rather than the career opportunities sports can provide.

In contrast, Anawalt said there are just concerns over fairness, even at the amateur level.

"This question of fairness is still important in a high school or junior high context because competitive sports are an entry to fame and fortune — even at that level. If you have one person that does well, they may get scholarships, they may get into a certain school when someone else does not," Anawalt said.