New study on transgender & performance. The paper’s title could've been “Significant endurance & strength-endurance advantages are retained for up to 2 years despite T reduction in TW: Implications for the assumptions of fairness in current policies”. Some thoughts to follow
First, remind ourselves of the principle and why the results matter. Sports policies have allowed inclusion of TW who lower T for 12 months on the assumption that this removes the male physiological advantages sufficiently to create fairness when women’s sport is “opened” up (2/)
The obvious (though amazingly unasked) question is “Is there evidence showing that this actually works? In other words, does T suppression remove the biological advantages that necessitate a separate women’s category in sport?" This is the question the study is trying to address:
The study includes 46 trans women (TW) and 29 trans men, all in the Airforce. It capitalises on the practice of physical fitness assessments every 12 months to track how performance in push-up, sit-ups and 1.5 mile run changes when T is either reduced (TW) or increased (TM) (4/)
The TW and TM results are, correctly, compared to ciswomen and cismen, respectively. They have data for over 2 million CM and 500,000 CW for these comparisons. So it’s about tracking the changes in performance with T alteration AND comparisons to the appropriate group (5/)
The main finding is that 1.5 mile run performance in TW remains significantly faster than in CW even after three years of T reduction. It starts 21% faster, and then TW do slow down, but remain 12% faster than CW in the third year. So T reduction doesn’t remove male advantage
Push-up and sit-up performance remains significantly better in TW than CW into the second year. By the 3rd year it drops to CW levels (more on that shortly). At 12 months (as per policy), the TW advantage is 37%, 19% & 13% for the 3 tasks, respectively (7/)
This is not the first evidence of retained advantage. There are a dozen studies, measuring variables ranging from lean mass to strength in TW, all showing that T suppression causes very modest reductions. This adds to that, in a trained cohort in functional performance tasks (8/)
One thing that is important (& as yet unknown) is whether the ‘targets’ for TW and TM changed in line with their gender identity. That is, there are minimum fitness standards that must be met by service members, and I’m not sure if those are changed for TW between Year 0 and 3
The reason this matters is that if standards differ for men & women (anyone know this?), AND IF TW are evaluated against a lower standard after beginning reassignment, then their incentive to do X push-ups and & Y sit-ups is reduced by design, amplifying the noted decline (10/)
So when push-up scores drop by 6% in Yr 1, 3% in Yr 2, and 20% in Yr 3, and sit-ups go -1%, 4% and 14%, is it possible that the large drop at the end is the result of conscious “pacing”, target-hitting, or group compliance? That seems important, I don’t know the answer yet (11/)
The other point, made in the paper, is that for push-ups, a body weight exercise, the TW are heavier than CW, so when they do say 33% more push-ups in 1 minute (Yr 2), the power output difference is even greater than the number suggests. As noted in the discussion of the paper:
So the picture is: Running performance is modestly reduced, so more than half the male advantage is retained into a 3rd year. In strength-endurance tasks, TW significantly outperform CW for 2 years, probably longer in absolute terms. This supports evidence from lab-trials (13/)
My CONCLUSION, then, is that there remains ZERO good evidence that T suppression can ensure fairness (or safety). There is now plenty of evidence that a large proportion of male physiological attributes and therefore performance advantages persist despite T suppression (14/)
The notion (or hope) that fairness and inclusion can be ‘balanced’, which underpins many policies and is even shared by many scientists, is unsupported, and indeed refuted, by the evidence available to us. Given limitations, more studies are of course required.
Finally, this is the latest study (of 13, I count) showing pretty much the same thing. They have limitations, but they are consistent & solid. The first of them was by Gooren, and it concluded, astonishingly, that because T suppression caused some strength reductions, that...
…TW could compete fairly with women depending "on what degree of arbitrariness one wishes to accept”. In other words, fairness can be arbitrary for women’s sport. But even then, it was clear that retained advantages would undermine the meaning of the women’s category (16/)
Unless of course, decision makers & academics decide this fairness (& safety, in instances where physical risk is a factor) is secondary in importance. Which, coming full circle to this study, is what would be implied if the policies didn’t recognise this latest evidence (end)
If this is the case, by the way, it means the TW performance potential may be greater than their scores suggest. They are “suppressed” by known targets, not physiology. Which means that the retained advantages despite T suppression would be even greater than shown in the study.
We did a podcast on this recently. It precedes this study (though I knew this was coming), but it explains the other dozen studies, the concept of balancing imperatives & why WR reached a guideline that keeps women’s rugby closed based on evidence to date:…

• • •

Missing some Tweet in this thread? You can try to force a refresh

Keep Current with Ross Tucker

Ross Tucker Profile picture

Stay in touch and get notified when new unrolls are available from this author!

Read all threads

This Thread may be Removed Anytime!


Twitter may remove this content at anytime! Save it as PDF for later use!

Try unrolling a thread yourself!

how to unroll video
  1. Follow @ThreadReaderApp to mention us!

  2. From a Twitter thread mention us with a keyword "unroll"
@threadreaderapp unroll

Practice here first or read more on our help page!

More from @Scienceofsport

29 Nov
The @dailymaverick asked me to do a piece on the trans woman in sport issue. It’s necessarily short and high level, but here it is. Writing it made me realize there are some key questions everyone who wades into the debate upfront should answer. Wanted to share them here (1/_)
The first question, before any other “shots are fired”, should be:

“If there is ZERO evidence for what happens to performance and/or biology in trans women undergoing treatment, what should happen for sport? Would you allow inclusion, or would you exclude until it exists?” (2/)
This is so important because it reveals a “value system” and understanding of women’s sport. If you believe in inclusion in the absence of evidence, you’re saying that women’s sport should be OPEN to self-ID, and then evidence must be provided to prove unfairness or risk. (3/)
Read 16 tweets
24 Oct
This is a sound and accurate logical explanation of why this notion of “matching for performance” to sidestep male and female sports categories is flawed. There are so many problems with it, one being that it fundamentally undermined the meaning of sporting competitions. (1/)
Another way to frame or conceptualise this is to recognize that if a female and male athlete are “matched” by this “unicorn-algorithm matching strategy”, the female athlete will be relatively better in their original category than the male athlete in theirs. Fundamentally unequal
A woman would be in say the 95th percentile for metrics like strength, speed, power etc, vs a men with equal numbers who is at around the 50th to 60th percentile for men. This “competition” enables relatively mediocre males to compete “equally” against excellent, top 5% females
Read 7 tweets
9 Oct
The World Rugby Transgender guideline is now out, and fully available here: You’ll also find a document called FAQs which tries to answer some common questions. We firmly believe it is the right thing in an emotive issue, for many reasons.
The Guideline is also accompanied by a visualisation that summarises the available physiological evidence that informed the Guideline. Here are those images, but I’d encourage consideration of all the issues - biological, legal, medical, social, ethical. All are in the doc & FAQs
As brief a summary as I can provide:
It is not possible to balance inclusion, safety and fairness. All the quality evidence, even if incomplete, strongly suggests that advantages are retained with welfare & performance implications. Therefore, players must compete in sex category
Read 10 tweets
9 Sep
Let me share a few thoughts on the latest #Semenya development - her appeal rejected by the Swiss Supreme court, World Athletics policy supported (pretty strongly too). We are planning a short pod on this tomorrow too, but here are a few thoughts… (1/…)
First, we’ve spoken a lot about transgender athletes recently. That has many elements to it. This has even more, and it’s really an unsolvable situation. It’s been present for nearly 100 years in sport, some horrendous attempts to manage it, and no clean solution in sight (2/…)
This decision establishes, for now, the policy that requires athletes with hyperandrogenism to lower T in order to compete. But not any hyperandrogenism, and not just any events. It covers only that caused by a selection of DSDs, where a person is 46XY, with testes, and thus (3/
Read 28 tweets
31 Aug
Last week, I posted a thread addressing a common criticism of transgender athlete policies, namely that they’re based on evidence in non-athletes. Here’s that thread, for a reminder. Today, I want to mull on another common issue raised in objection: (1/)
The objection is this: People argue that because trans women are often smaller, lighter, slower, weaker etc than biological females, it should be fine for them to compete as women. It’s an “overlap argument". Here’s one example of that thinking (this particular poll backfired): Image
The premise of the argument is this:
- Testosterone confers upon males advantages including size, strength, speed, power. This is why women have a separate category;
- If someone identifies as female (trans women), provided they’re not too big, strong, fast, they can compete as W
Read 15 tweets
24 Aug
This has been a common argument in the trans women in rugby debate. People have the idea that unless you *directly* study rugby AND show that TW cause injuries, it can’t be evidence based. Of course it can - there are peer reviewed studies that show two related things (thread)
2/ First, you have so many studies that identify both performance determinants and risk factors for injury in rugby. Dozens of studies identify when injury occurs, and thus what the significant risks for injury are. Similarly, performance is multifactorial but is KNOWN to be...
3/ …significantly influenced by a handful of testable/measurable factors. In fact, these measurable factors are so crucial and “robust" that teams actually have minimum standards for them, and select or drop players based on achieving these targets. They’re not “guesses”.
Read 22 tweets

Did Thread Reader help you today?

Support us! We are indie developers!

This site is made by just two indie developers on a laptop doing marketing, support and development! Read more about the story.

Become a Premium Member ($3/month or $30/year) and get exclusive features!

Become Premium

Too expensive? Make a small donation by buying us coffee ($5) or help with server cost ($10)

Donate via Paypal Become our Patreon

Thank you for your support!

Follow Us on Twitter!