By: Jay Kang (they/them)

In the summer of 2022, Lia Thomas became the face of NCAA Women’s Swimming. Not because she had just won the women’s 500-yard freestyle in an NCAA Division I national championship, but instead because she was the first openly transgender athlete to achieve such a feat. Rather than celebrate a proud ending to a collegiate athlete’s career, many took umbrage with the fact that a woman who was assigned male at birth (AMAB) “took first place from” a woman who was assigned female at birth (AFAB).

Since this debacle, many news articles have circulated and discussed the place trans people – people who identify as a gender different from their biological sex – have in athletics. However, many of these views are based on personal biases and feelings rather than scientific facts. Let’s take a moment to break down some of the data that exists regarding trans folks in sports.

When we say “male” or “female”, what are we specifically referring to? In science, it depends on the context! For instance, one definition of sex is that males cannot give birth and females can. However, a woman who is sterile is not automatically considered to be male. Another definition is that males have a male sex organ while females have female sex organs. However, does that mean that a man who is castrated is automatically a woman? – Clearly, asking these questions illustrates that the answer is more nuanced than black-and-white thinking may initially suggest.

In the context of sports, we often define “male” and “female” in terms of hormone production. In most sports rulings, males are defined as people who produce more testosterone whereas females are defined as people who produce more estrogen. Testosterone is the primary male sex hormone that helps facilitate the development of male reproductive organs as well as the promotion of male secondary sex characteristics like muscle growth and bone mass. Estrogen is the primary female sex hormone that, like testosterone, helps develop female reproductive organs and secondary sex characteristics like breasts. Males and females produce both estrogen and testosterone, but biological males tend to produce more testosterone than estrogen, whereas the opposite is true for females.

Hormones are chemical signals that travel through the blood to different organs in the body. The difference between hormones and other signaling molecules in your brain (like neurotransmitters) is that hormones can travel relatively long distances to facilitate communication between different organs, whereas neurotransmitters signal over short, localized distances. For instance, estrogen, which is primarily produced in the ovaries, is released into the bloodstream where it binds to estrogen receptors in the skeletal muscle. The estrogen then tells the skeletal muscle to grow, encouraging muscle and bone growth¹. Similarly, testosterone is produced in the testes and travels through the blood to reach the skeletal muscle. There, testosterone binds itself to androgen receptors located inside a muscle cell’s nucleus. Once bound, testosterone stimulates protein synthesis and inhibits protein degradation. which is why people who have testosterone tend to maintain their muscle mass for longer². These hormones are often called sex hormones or androgens as they are derived from sexual organs.

Transgender people are people who do not identify with the sex assigned to them at birth. For instance, a trans woman is a woman who identifies as a woman despite being born with male genitalia. Gender dysphoria is when an individual feels distress or unease due to their physical body presentation not matching their gender identity³. For instance, most people would be distressed if they could not recognize themselves in a mirror – this is the experience many trans people feel every day. To combat these feelings, trans individuals may undergo hormone replacement therapy (HRT) as a part of their gender affirming care – that is, the social, psychological, behavioral, and medical interventions designed to affirm an person’s gender identity, as defined by the World Health Organization.

HRT is the process of injecting additional hormones into the body to cause the body to change in response to the hormone given⁴. This treatment was traditionally given to women undergoing menopause to alleviate their symptoms⁵ and have taken an additional role in helping trans folks feel more at home in their bodies. Menopause is signified by a dramatic decrease in estrogen levels. Doctors prescribe estrogen to menopausal patients to alleviate some of the more unbearable symptoms of this hormone shift. Similarly, trans women take estrogen as a form of hormone replace since they do not naturally produce high levels of the sex hormone.  HRT involves taking medication that will 1) decrease the production of the native hormone and 2) increase the availability of the desired hormone. In other words, a trans man may take testosterone to supply additional testosterone to the body and sometimes an anti-androgen drug to block to native production of estrogen.

The decision to socially and physically change is not something anyone takes lightly. To even start HRT, a trans individual will need to see multiple healthcare providers like endocrinologist, mental health specialists, and primary care physicians. Additionally, many insurance plans may not cover the cost of gender affirming care, even if the company accepts that it is medically-necessary procedure. With this being said, the decision to transition is a deeply involved and heavy choice, and not something anyone would take likely. For trans individuals who seek out gender affirming hormone therapy, the process – even once medically approved – can be a long and arduous one. Some alterations like voice changes or hair growth can be permanent, and it can take over 5 years for some of these changes to even occur. The idea that a person would undergo this process to obtain some kind of biological advantage over cis-women – biological women who identify as women – in a sporting competition is frankly preposterous.

In most NCAA sports, a trans female student looking to participate cannot compete on the woman’s team until they have completed testosterone suppression medication, or treatment to specifically block the production of testosterone, for at least one calendar year. Some sports have even discussed having a testosterone blood test⁶ or genetic test to ensure that the participating athlete is sufficiently “female” to qualify. However, putting this into practice can get complicated quickly – because even the anatomical “male” and “female” designations of human biology itself can be less rigid than many think it to be.

Caster Semenya is a gold medalist middle-distance runner from South Africa. She came under fire after her victory in the 2009 World Championships. After winning first place in her race during the 2009 championship, critics of her achievement demanded she take a sex verification test to verify that she was a biological woman. It was later revealed that Semenya has an intersex condition, a biological condition that does not fall under the traditional male/female binary, where her natural testosterone levels resembled a cisgender male’s (a person born with male sex genitalia and identifies as a man) levels. However, does this genetic condition disqualify her as a woman despite having competed as a woman all her life? According to an op-ed piece she wrote in the New York Times, Semenya did not realize she had this condition until the sex verification test in 2009. While her medals were not taken away from her, she had to fight tooth and nail to keep them rightfully in her possession.

Most recently, Stephanie Turner refused to fence a transwoman fencer at a regional fencing tournament in Maryland in March 2025. Turner stated that she “loved and respected” her opponent but went down on one knee and refused to acknowledge her opponent as the woman she was. Turner stated that only biological women should be fencing in a woman’s tournament, and was subsequently disqualified for refusing to fence her opponent. Turner was awarded a $5000 prize from an anti-trans organization for her “courage.”

To bring this back into real-world numbers, 0.6% of the US population identifies as trans. A smaller subset of that 0.6% are going to be people interested in sports, and an even smaller subset will be people who choose to follow an athletic career into and following college. There is a worry among those against trans people’s participation in sports that cisgender men may desire to undergo HRT to compete in women’s events in order to take medals away from women. However, as outlined above, the process to receive HRT is long and arduous, for numerous logistical, personal, and medical reasons; in keeping with this – as of the publication of this article – there have been no notable instances of this concern becoming a reality.

The increased opposition of trans women in women’s sport is unjust, cruel, and unanchored in science. As shown in this article, sex is a fluid description, and there is no one way to identify as a woman. Instead, we should be celebrating feats of exceptional athletic performance, specifically at the collegiate level when athletes are in their prime years. So when Lia Thomas, Caster Semenya, or any other gender nonconforming person arrives at the starting line, we as a people should be excited to see what spectacle they’re about to perform.

TL; DR

• What makes a biological male or female their supposed genders is a scientifically fraught subject! Sex can refer to genitalia, the ability to give birth, or if they produce more estrogen or testosterone.
• Hormone Replacement Therapy (HRT) can be used to suppress one’s native hormone and increase availability of the desired hormone. It was previously used to help mitigate the effects of menopause where women experience a decrease in estrogen production.
• Transitioning is a long process and is not a decision to take lightly.
• Sometimes the winner of a sport will be born trans, just like Shaq was born tall or Michael Phelps had long arms

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Reference
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