Recently, the issue of transgender inclusion in sports has made its way into the world of powerlifting, with both sides arguing over whether or not trans athletes should compete as the gender of their birth or the gender they identify as now. Everyone from athletes involved in the sport to politicians have weighed in on the matter, and to give some clarity to the complexity surrounding these arguments, we decided to dig deeper into the actual science (or lack thereof) behind the impact of transgender inclusion in powerlifting—specifically, transgender women competing in the women’s divisions.

Socially, the issue of trans participation in sport is complicated and widely misunderstood. According to the American Journal of Public Health, in 2016, it was estimated that 390 adults per 100,000, or 1 million in total, identify as transgender—which means 0.003% of the American population fits into this group. That small sample size is one reason why the research on trans inclusion in sport, one way or the other, is scant.

The British Journal of Sports Medicine published a review, titled “Gender identity and sport: is the playing field level,” authored by Jonathan Reeser, a physical medicine & rehabilitation specialist in Marshfield, WI.

The aim of the report was to “examine gender identity issues in competitive sports, focusing on the evolution of policies relating to female gender verification and transsexual participation in sport.” The report concluded: “Although the psychosocial arguments in favor of allowing transsexual participation would appear to be relatively uncomplicated, there is in my opinion inadequate physiological performance related data to allow an unambiguous position to emerge. It seems clear, however, that every sports authority or governing body, indeed every athlete, will ultimately need to wrestle with these issues and answer the questions raised above.”

USA Powerlifting, which on May 9 decided to uphold its policy that excludes trans women from competing in the women’s division, has done its own wrestling. “There’s no data on male-to-female transitions in powerlifting,” says USAPL President Larry Maile. “For the same reasons that, probably, most small groups that are often subject to prejudice experience, they don’t want to be studied in essence. But it’s a low number as well, and that provides its own difficulties.” 

The first question that they aimed to answer is: “Are there really [strength] differences between men and women?” The USAPL turned to its parent organization, the International Federation of Powerlifting, and looked at its database of lifters. They studied the strength differential between cisgender (someone whose gender identity corresponds to the sex they were assigned at birth) men and women in the non-elite category and found that men were 61 percent stronger. That number shrinks to between 30 percent and 40 percent for elite lifters.

Maile says that a cisgender man’s strength is also a result of other factors, so he focused specifically on the bench press since, “that lift benefits from greater upper-body muscle mass, wider shoulders, and shorter arm length.” When it comes to benching, men are 91 percent stronger than women.

“We’re not making comments on other people’s sports,” Maile continues. “What we do know is that powerlifting is a high-strength, low-technique sport. Especially at the non-elite level, you can have crappy technique and still do well.” 

“And if you look at the numbers within my federation, the difference is stark compared to elite powerlifters,” says JayCee Cooper, the transgender woman initially banned by the USAPL back in January and the catalyst to these issues being brought into the mainstream. Cooper is comparing herself to the 84-kilogram female lifter Bonica Brown. “In my last meet, I squatted 320 pounds; she can probably squat 320 kilos.” [Brown has squatted 318 kilograms, or 715 pounds.]

The USAPL also claims that males transitioning to females have high levels of androgens, like testosterone, which give those competitors an advantage, with the organization even citing, “increased body and muscle mass, bone density, bone structure, and connective tissue.”

Again, this all boils down to a simple question: Do transgender women powerlifters have a physical advantage over other female competitors?

Well, not if you ask Dr. Laura Arrowsmith, a practicing physician in Tulsa, Oklahoma and a transgender woman herself. Not only does Arrowsmith think that transgender women powerlifters don’t have a physical advantage over cisgender females, but she’s calling USA Powerlifting’s ruling to ban transgender women “an incorrect decision” and one that’s “probably based on prejudice and a lack of information.”

“If transgender women have been on hormone therapy even for a few months, their testosterone has fallen to negligible levels and they’ve lost muscle mass because of that, so there really is no advantage,” Arrowsmith says. “We’re on typically two different medications [while transitioning]: One medication blocks the production of testosterone. It’s an anti-androgen. The other medication is to feminize the estrogen that we take.”

Arrowsmith wasn’t willing to go down the opposite slope in saying that transgender women powerlifters are at a disadvantage, but did cite her personal experience in detailing how transitioning weakened her physically.

“I’ve always had a horse ranch most of my life, and I did a lot of the work around the horse ranch. Once I started on hormone therapy, there were so many things I could no longer do,” she says. “I went from being able to easily pick up a bale of hay or a bag of horse feed to really struggling to do either one. I just didn’t have the muscle strength anymore.”

Joshua Safer, M.D. at the Icahn School of Medicine at Mount Sinai and executive director of the Center for Transgender Medicine and Surgery in New York City, agrees, saying, “There is no data to suggest that transgender women powerlifters have a physical advantage over non-transgender women powerlifters.”

Arrowsmith listed transgender women having naturally larger hands, which hormonal medications don’t alter, as the one possible advantage she could think of. But even that wouldn’t translate to grip strength, which involves muscle, according to her. She also said that a transgender woman wouldn’t have advantages in pinpointed powerlifting areas such as tendon strength, leveraging, bone density, or lifting mechanics, either. And Safer tends to agree, actually laying out the premise that transgender women powerlifters on hormonal treatment could be at a “disadvantage.”

“If height alone were an advantage, a transgender woman might have that,” he says. “But for many sports, a transgender woman might have a disadvantage, because she would be carrying around a larger body with smaller muscles.”

Those assertions and the International Olympic Committee allowing transgender women to compete against cisgender women—as long as their testosterone is five nanomoles or less—seemingly makes USA Powerlifting’s decision all the more baffling.

When asked about its policy, the IOC issued a statement, saying it “aims to balance inclusivity, fairness, safety and a level playing field for all athletes” and that “we expect to publish updated Transgender Guidelines following a lengthy consultation with (among others) the IOC Medical and Scientific Commission; medical, scientific, human rights and legal experts across relevant fields; and various stakeholders and other interested parties, including international federations and national governing bodies.”

*Additional reporting by Mark Lelinwalla