Here’s What Science Actually Says About How Gender Affirming Hormones Impact Sport
Anti-trans campaigners love to spruik science in the debate but surprise surprise, the arguments don't add up.
Trans women and the ongoing debate as to whether or not they should be allowed to compete in elite sports has dominated headlines in recent weeks, with those opposed to their participation largely claiming biological advantages as a reason for exclusive policies.
The topic has raged on for months now but came to a head last week when FINA — the world governing swimming body — moved to effectively ban trans women from the sport, a decision that has immediately devastating impacts on Penn swimmer Lia Thomas, who hoped to trial for the US Olympic team.
Since then, other sporting codes have quickly followed suit — including rugby league, which banned trans women’s participation at an international level.
“Until further research is completed to enable the IRL to implement a formal transgender inclusion policy, male-to-female (trans women) players are unable to play in sanctioned women’s international rugby league matches,” a statement from International Rugby League read, citing the International Olympic Committee’s (IOC) new guidelines and the freedom for sports to make their own ruling within the guidelines as a reason for the ban.
Meanwhile, FIFA, World Athletics, and the World Netball Federation will all review their own policies — with no clear indication if they will implement exclusionary bans.
However, the IOC’s framework — within which sports are allowed to form their own trans inclusion policies — stresses that any restrictions must be based on robust and peer-reviewed scientific evidence. So what exactly does the science say?
The Science Says Very Little About Trans Womens’ Advantage In Sport
Despite the arguments you may have read on social media amid the ongoing trans-athlete debate, we actually don’t have much evidence at all to support the theory that trans women have an advantage in sport. This isn’t to say they do not have an advantage, but we know very little about how gender-affirming hormones impact athletic ability in general, let alone in extremely niche, elite-level sports.
Dr Patrice Jones, a Victorian University researcher leading a study examining the impacts of gender-affirming hormone therapy in sports agreed that we cant issue a one-size-fits-all policy when it comes to sport — a point made by the Australian Olympic Committee last week — but noted that limited data makes it extremely difficult to actually understand how gender-affirming hormones may impact athletic ability in a positive or negative way.
“I agree that there is no one-size-fits-all policy that can be implemented for all sports. What would constitute a ‘performance advantage’ differs by sport, it very much depends on the nature of the sport. For example, differences in strength and body size between competitors may be a key factor for high contact sports such as rugby, which higher body mass favourable,” Jones told Junkee. “In endurance-based events such as cycling, running and swimming, measures of aerobic capacity may be more important, with lower body weights favourable. Considering this, it doesn’t make sense to create a blanket policy that may specify thresholds for performance markers that aren’t equally important across all sports.”
However, Jones stressed that the data we know most about relates to body composition and testosterone levels, which aren’t necessarily key factors in athletic advantage, despite being key components of many trans-exclusionary arguments.
“We know the most about changes in body composition and testosterone levels — which aren’t perfect indicators of athletic capacity,” said Jones. “We have more limited data on strength changes, and haven’t explored direct measures such as aerobic capacity, which would be important in endurance-based sports like swimming. We also lack long-term studies (2+ years) that could tell us if there are further performance changes in trans women and trans men using gender-affirming hormones over time.”
Perhaps the biggest issue at play when it comes to actually getting this evidence is the fact that there simply aren’t that many trans athletes competing at an elite level — let alone in specific sports. And, from a scientific perspective, this makes it incredibly difficult to differentiate between what could be a genuine advantage for trans women across the board, and what is simply an outlier.
“A big limitation is that most of our knowledge comes from research in untrained trans populations and not in specific sports setting (i.e. every trans people who are non-athletes — there are so few trans athletes competed at elite levels),” said Jones.
Due to the fact that so few trans athletes have actually competed at an elite level, the peer-reviewed data relating to any advantages or disadvantages in specific sports in the short and long term, it remains difficult to conclusively make any evidence-based decisions regarding participation. So basically, we simply don’t have the evidence to conclusively prove how, if at all, gender-affirming hormones impact athletic ability, so introducing trans-exclusionary policies in sports at this stage doesn’t actually align with the IOC’s framework.
Experts in the field — including Jones — have stressed that exclusive decisions without conclusive evidence to support them send harmful messages. It opens the gates for sporting bodies at elite and grass-root levels to make further exclusive decisions,” Jones told the SMH on FINA’s policy last week. “This risks the wellbeing of everyday trans people and sends harmful message that they are not accepted in sports and broader active spaces.”
At this point, policies introduced while the science is unclear do very little — if anything — to protect the fairness of sport, but have detrimental impacts on those who are now excluded.