The Issue of Transgender Women in Sports.

Interviews are a great way to explain certain topics.Their drawback, however, is that they don’t always manage to capture the full depth of the issue. That was also the case with my interview for DVTV on the topic of transgender women in sports. This text follows up on that interview, which can be viewed here: DVTV – Transgender in Sports.

The Issue of Transgender Women in Sport. Interviews can be a great way to explain complex topics. Their weakness, however, lies in their inability to always reach the full depth of an issue. That was the case with my interview for DVTV on the topic of transgender women in sports. This text is a continuation of that conversation and aims to stick strictly to facts and objective parameters.

Facts First

It is essential to distinguish between biological sex and gender. In sport, categories have historically—and logically—been defined by biological sex. The question of transgender athletes, however valid, has only emerged in recent years. Women’s categories in sport were created in the early 20th century to protect fair competition—long before scientific data existed, it was clear that male and female performances were fundamentally different in many sports. Without such separation, women would be at a clear disadvantage.

Categories in sport exist to ensure fair chances of success. Whether based on weight (boxing, weightlifting, MMA), age (youth competitions), technique (foil vs. sabre), or sex, they aim to level the playing field. Men’s and women’s categories have always been based on biological sex, not social gender.

The Performance Gap

Differences in performance between sexes are substantial, especially in power and speed-based sports. For example:

• Muscle strength in biological males is 30–40% higher

• Speed is 10–15% greater

• Punching force is up to 160% higher

• VO₂ max is 20–40% higher

These differences undermine the fundamental fairness of women’s categories when an athlete with male physiological characteristics competes in them. It’s akin to allowing a super-heavyweight boxer to fight a lightweight—regardless of skill, body mass and strength become overwhelming advantages. Mental and motivational factors, influenced by long-term androgen exposure, may also persist even after a gender transition.

Inclusion Matters Too

Of course, we can’t ignore the importance of inclusion. Gender equality and the right to self-determination are critical societal values. But in competitive sport, inclusion must be regulated, especially if it undermines fairness.

The inclusion of transgender men (biological females transitioning to male) has been widely accepted, primarily because testosterone therapy is carefully monitored and kept within physiological male ranges. These athletes do not gain an unfair advantage and often compete successfully without issue.

The situation is very different for transgender women.

The Current Rules

As of now, the 2015 IOC guidelines allow biological males who identify as women to compete in women’s events if their testosterone level has been below 10 nmol/L for one year prior to the Olympics. This limit was based on data from women with polycystic ovary syndrome (PCOS), using a +5 SD range to capture even the highest natural female testosterone levels. However, 10 nmol/L is also the lower limit of the male range.

At the time, this was the only politically and socially acceptable compromise before the 2016 Rio Olympics. The scientific data on how this affected athletic performance was not yet available.

What Happened Next

The problem with the 2015 rule became immediately apparent in Rio, where the top three finishers in the women’s 800 meters all had hyperandrogenism (a medical condition where women have male-like hormone profiles). Important clarification: this is not the same as being a transgender woman. These athletes are biological females, but with high androgen levels. Still, the case illustrates the powerful performance effect of testosterone.

As a result, some federations (e.g. athletics) lowered the limit to 5 nmol/L, while others (e.g. rugby) banned inclusion entirely.

Recent studies on transgender women who reduced testosterone levels showed that some values dropped quickly (e.g. hemoglobin), but most physiological advantages remained, with only slight decreases from baseline levels. That is, the hypothesis that testosterone suppression for one year would eliminate unfair advantage has not been confirmed.

This makes sense: the primary effect of testosterone happens during puberty, not adulthood. Up until puberty, boys and girls gain strength at a similar rate. But during puberty, boys experience exponential acceleration, while girls continue on a linear path. The body structure is shaped during this period—and a brief period of hormone suppression later in life cannot reverse those changes.

We’ve seen similar effects in doping cases: muscle cells can retain the advantages of anabolic steroids even four yearsafter they are stopped.

Fairness vs. Inclusion

Given all of the above, the current rules do not ensure fairness—especially in sports where strength, mass, and speed play dominant roles in performance. We need a more thorough, respectful, and evidence-based discussion. It’s likely to be heated, as values clash on both sides.

Ethically, we must ask: Where do the rights of one individual end, and those of others begin? We're not just talking about a handful of transgender athletes, but also hundreds or thousands of their competitors, who could be unfairly denied their chance at fair competition.

Some proposals, such as creating separate categories, are unworkable. In Olympic sport, there are only three medals per event. If a transgender athlete wins one, someone else doesn’t. If their biological advantage is measurable, that means someone else’s opportunity was taken—not because they were outperformed fairly, but because of physiological inequality.

A Path Forward?

There’s a path we rarely discuss. Let’s return to 1900 Paris, when women first competed at the Olympic Games. They were given separate categories to protect fair play. Why not do the same today?

Let’s define women’s categories strictly by biological sex. Leave out hyperandrogenism for now—that’s a separate, complex issue. Allow transgender women to compete in the male/open category. Yes, their chances of winning may be lower—but this may be the only way to preserve fairness while still offering inclusion.

Alternatively, we could evaluate each sport individually, based on how much performance is influenced by biological sex. In power and speed events, the effect is clear and inclusion should be limited. But in skill-based events like shooting, certain gymnastics disciplines, or synchronized swimming, the effect is negligible—and inclusion is more easily justified.

Most sports will fall somewhere in between. And this is where the real debate lies.

Closing Thoughts

Yes, everyone wants to win. But only a few combine talent and years of disciplined work to earn that right. Taking that opportunity away—no matter how well-meaning the intention—is simply not fair.

Transgender athletes absolutely have the right to train and enjoy sport. But in elite and professional competition, we must apply clear criteria: fairness must take precedence over inclusion.