Let The Data Do The Talking: The First Study Comparing Trans and Cisgender Athlete Performance Sparks Controversy

On April 10, 2024, the British Journal of Sports Medicine published a groundbreaking, peer-reviewed study examining the performance metrics of trans and cisgender athletes in a laboratory setting. This research is the first to compare athletic performance between these groups in a controlled environment, aiming to challenge the precautionary bans and eligibility exclusions imposed by elite sports organizations. Unsurprisingly, the study sparked a heated online debate about the integrity of the research and the implications of its findings in the highly politicized discussion surrounding trans women's participation in women’s sports.

Funded by the International Olympic Committee, the study compares four groups of trans and cisgender athletes (12 trans men, 19 cisgender men, 23 trans women, and 21 cisgender women) on their body composition, bone mass, strength, and relative cardiovascular fitness. All participants played competitive sports or underwent physical training at least three times a week. None of the participants were athletes competing at the national or international level. All trans women athletes had undergone at least a year of testosterone suppression and oestrogen supplementation.

With similar testosterone concentration levels between trans and cisgender participants, the authors found that trans women in the study have higher handgrip strength, lower lung function, lower relative VO2 max, and lower relative jump height than cisgender women athletes. Meanwhile, trans men participants have lower handgrip strength and lower absolute VO2 max than their cisgender counterparts.

The study’s findings can be summarized in the following points:

Trans women exhibit a different endocrine profile than cisgender men and women in terms of oestradiol concentrations. With oestrogen supplementation, trans women athletes have the highest fat mass percentage of all groups, due to the role of oestradiol in fat accumulation.
Trans women are, on average, taller and heavier than cisgender women and trans men.
There is no significant difference in bone mass density between trans women and cisgender women athletes, countering previous research suggesting that trans women have a considerable bone density advantage over cisgender women.
Trans women athletes exhibit a lower FEV1: FVC ratio than cisgender women, indicating lower lung function, which may result in lower performance compared to cisgender women.
Trans women have lower relative jump height than cisgender women, indicating a relative lack of lower body anaerobic power.

An important objective of the study is to argue that trans women are not biological men. The results imply that using cisgender men as proxies for trans women and using non-athletic trans women populations as representative data, are inadequate to justify the ban on trans women athletes in women’s sports.

As the first study of its kind to investigate the physiological differences between trans and cisgender athlete populations, the authors highlighted the study’s limitations and called for further research to address the complexity of trans athletic physiology. However, anti-trans camps heavily attacked the study. Their comments, grouped into four major types, reveal logically unfounded transphobic criticism:

Questioning the integrity of the research: Critics claim political motives tainted the research, and trans women participants may have manipulated data.

As an academic, you can fake almost any study with some basic tricks. Anyone who ‘trusts the science’ blindly is brainwashed and doesn’t understand science.- source: SwimSwam

It’s never going to be possible to create a fair study as any man posing as a woman has a vested interest in deliberately underperforming in order to cheat his way to where he wants to be. – source: Mumsnet

Chief author Blaire Hamilton has been attacked as biased because she was one of the first trans women to compete in university women’s soccer competitions. Anti-trans critics accuse trans women participants of manipulating self-reporting data, ignoring that the study underwent rigorous peer reviews and included clinically tested testosterone concentration levels.

2.Unfair comparison: Some argue that comparing unfit transgender women to fit cisgender women is unfair.

The transwomen were relatively unfit and overweight compared to the female reference group. So, the finding is: ‘Relatively inactive and overweight males do worse on some measures of athletic performance than significantly fitter and more active females.’- source: SwimSwam

Trans women participants have higher body mass index (BMI) which could suggest they are less fit. However, BMI is an inaccurate measure of obesity and fitness status, and the study notes similar fitness status among the different groups of athletes based on anaerobic threshold (% VO2 max).

3.Small sample size: Critics argue that the small sample size of transgender athletes is “statistically insignificant” for generalizable results.

The small number of transgender athletes reflects systemic oppression, as they face barriers and restrictions in participating in sports. The authors conclude that this study “does not provide evidence that is sufficient to influence policy for either inclusion or exclusion.”, and encourages future research to study trans women athletes as a separate demographic group rather than lumping them with cisgender men.

4.Protect women’s sports: Critics claim men become women to repress women in sports

The patriarchy feels threatened so men are becoming women to repress women again. -source: SwimSwam

This logic resembles the “bathroom predator” myth, where right-wing groups fabricated stories of sexual harassment in trans-inclusive restrooms. In reality, the nitpicking around the axis of gender and sex based on fairness indicates that women’s oppression in sports stems from systemic gender inequity, not from trans women’s participation. The obsessive focus on a few successful trans women athletes only perpetuates fear-mongering and justifies regulating women’s bodies and identities.

Joanna Harper, known for her research on trans women runners, noted in a recent interview that trans athletes have become the “whipping children” for those who do not care about sports. Blaire Hamilton and her research team have proven scientifically that the differences between trans and cisgender athletes are not as significant as conservative, elite sports organizers claim. As Hamilton rightfully said, let the data do the talking.