As debates rage over the inclusion of transgender women in sports, one central question remains: Do trans women have a physical edge over cisgender women? The answer, according to scientists and medical experts, is complex — and far from conclusive.
Across the U.S., more than half of all states have banned transgender women and girls from playing on sports teams that match their gender identity. These laws have spread quickly, even though very few transgender athletes have competed at elite levels — and even fewer have won major titles.
The discussion has intensified since swimmer Lia Thomas won an NCAA title, leading to loud calls to exclude trans women from women’s sports. Former President Donald Trump has made the issue a political talking point, issuing executive orders and even threatening to pull federal funds from California over one high school athlete’s participation.
What the Science Says — and Doesn’t
Critics of transgender inclusion argue that adult trans women, even those who undergo hormone therapy, maintain unfair advantages from going through male puberty. They believe this can lead to a loss of opportunity for cisgender women.
Trans athletes and their supporters disagree. They say there’s not enough evidence to support sweeping bans. They also stress that sports offer important mental, physical, and social benefits — and trans people deserve access to those benefits, too.
Experts agree that research in this area is still limited. Most studies are small and don’t look at individual sports in depth. There are no large-scale scientific studies that clearly define how transitioning affects athletic performance in areas like sprinting, swimming, or wrestling.
Hormone therapy can change physical traits like muscle mass and strength, but scientists say the effects vary. And even among cisgender athletes, natural physical differences — such as height, bone density, or grip strength — can affect performance in different ways depending on the sport.
This lack of clear evidence has not stopped many sports organizations from changing their rules. For example, the NCAA reversed its previous inclusive policies and now largely bans trans women from competing in women’s divisions. Trans men, however, are still allowed to compete on men’s teams.
How Many Trans Athletes Are Competing?
Part of the confusion comes from the lack of reliable data. No one knows exactly how many transgender athletes are competing — at any level. This allows both sides of the debate to make exaggerated claims.
In elite sports, the number of openly trans athletes remains very small. Since the International Olympic Committee began allowing trans athletes to compete in 2003, fewer than a dozen have qualified. Most have competed according to the gender they were assigned at birth.
Only one trans woman — New Zealand weightlifter Laurel Hubbard — has ever qualified for the Olympics. She did not complete any lifts in her event.
At the college level, numbers are also low. NCAA President Charlie Baker told the U.S. Senate last year that fewer than 10 trans athletes were known to be competing in the NCAA. That’s less than 0.002% of the total athlete population.
In 2023, the NAIA (a smaller U.S. college sports league) banned trans women from competing in most women’s events. A spokesperson admitted they didn’t know how many trans athletes were competing in their programs — if any.
The Williams Institute at UCLA estimates that around 122,000 trans youth ages 13–17 could be playing high school sports. But it’s unclear how many of them compete on teams that match their gender identity — especially in states with strict bans.
What Role Does Puberty Play?
Experts say that puberty — especially male puberty — can bring physical advantages that may impact sports performance. The key factor is testosterone.
Testosterone is a hormone produced by all bodies, but it plays a bigger role in male development. In puberty, boys see a dramatic increase in testosterone levels, which can lead to larger muscle mass, stronger bones, greater height, and faster speed.
Dr. Bradley Anawalt, an endocrinologist from the University of Washington and advisor to the NCAA, explains that before puberty, boys and girls are physically similar. “But once boys hit puberty, testosterone levels shoot up, and you start seeing big changes in size, power, and speed,” he said.
Some research suggests that boys exposed to higher testosterone levels even in the womb may see small athletic benefits later in life. But overall, scientists agree much more data is needed to say whether trans women maintain lasting advantages after transition.
Why This Debate Matters
The debate over trans athletes is about more than trophies. It touches on science, fairness, identity, and politics — all in one high-stakes conversation. But with so little solid data and so much public opinion, many policies are being made without a clear scientific foundation.
Advocates for trans inclusion say that focusing only on potential advantages misses the bigger picture: Trans athletes, like all athletes, compete for the love of the game — not just to win.
As the conversation continues, researchers and sports organizations are being called on to study the issue more carefully and find solutions that are both fair and inclusive. Until then, the debate will likely continue — on the field, in the courts, and across the country.
