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The debate over whether transgender female athletes should be allowed to play girls' and women's sports has exploded this year. More than 30 states have introduced bills that would ban them from participating. The issue is emotionally charged, and it's hard to find a middle ground. But NPR's Tom Goldman reports on a pioneering researcher trying to get there.
TOM GOLDMAN, BYLINE: With the simple act of signing his name, Mississippi Governor Tate Reeves turned the debate over transgender female athletes into reality.
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TATE REEVES: Senate Bill 2536, the Mississippi Fairness Act, is now law.
GOLDMAN: The law, banning transgender athletes from high school and university female teams, is scheduled to take effect this year. The legislation Reeves signed in March and other similar state bills cite science to make the case that after puberty, transgender female athletes have an absolute advantage over cisgender female athletes, even after therapy to reduce the powerful hormone testosterone. And therefore, the trans athletes should be banned from female sports. But none of the lawmakers behind these bills reached out to Joanna Harper.
JOANNA HARPER: My official title is Ph.D. researcher at Loughborough University.
GOLDMAN: Unofficially, Harper is a scientist in the middle of a debate that's being waged at the angry extremes between those who want to ban and those who want blanket inclusion - any person who identifies as female can play women's sports. The banning side doesn't want to hear this.
HARPER: In most sports, after hormone therapy, it is perfectly reasonable to allow trans women to compete against cisgender women.
GOLDMAN: That's because the therapy, Harper says, can make the playing field more level, even though trans women still can retain advantages like strength and size after transitioning. She believes hormone therapy should be required at high levels of sport, and that restriction angers some on the other side.
HARPER: There are people who consider me a traitor to trans people.
GOLDMAN: What she is is a pioneer in transgender research, which Harper never intended to be. Seventeen years ago, she started taking pills to add estrogen and block testosterone as part of her transition from male to female. She also prepared to change athletically. At one time, she was ranked among the top male distance runners in her native Canada.
HARPER: Within nine months of starting hormone therapy in 2004, I was running 12% slower.
GOLDMAN: Which both bothered her as a competitor and intrigued her as a scientifically curious person - so she started collecting data. She got race teams from eight transgender women before and after hormone therapy. One of the effects of reducing testosterone is reducing hemoglobin, which carries oxygen-rich red blood cells throughout the body. It provides fuel for endurance athletes. And with less, the athletes slow down, which is what happened in Harper's study. Collectively, the women were more than 10% slower after therapy.
HARPER: And that's an important number because that's the difference between serious male distance runners and serious female distance runners - 10- to 12% sort of range.
GOLDMAN: In 2015, she published her data in the first paper on transgender athletes. She then wrote the book "Sporting Gender" and helps sports organizations like the International Olympic Committee craft policies in the middle - inclusive of transgender female athletes and restrictive by requiring them to undergo hormone therapy. Dr. Eric Vilain, a Washington, D.C.-based geneticist and expert on sex differences, said Harper's research has been groundbreaking.
ERIC VILAIN: Looking at data on trans athletes, I don't see that there is any kind of fear to have that suddenly the world of sports is going to be topsy-turvy and very unfair for all women out there.
GOLDMAN: It's harder to assess the impact with younger trans athletes. High schoolers develop at different rates, making it tough to create one-size-fits-all rules. Plus, the numbers are so small. Harper says transgender people make up less than 2% of the population, and trans kids are one-sixth as likely as cisgender kids to go out for school sports. Still, the debate rages, and Harper's goal of pulling people toward the middle continues. Since 2019, she's been at Loughborough University, a prominent sports science school in England. Harper says the science of transgender athletes still is in its infancy. She's broadening her research to different sports, fueled by a personal mantra - more data will lead to better policies.
Tom Goldman, NPR News. Transcript provided by NPR, Copyright NPR.