@JaneSpeakman1@HJJoyceEcon Scientist: Oh look, half the people have a dangly thing between their legs and the other half are way less weird looking. I wonder if this division is important?
RW: Nah, I don’t think so.
@JaneSpeakman1@HJJoyceEcon Scientist: But look, the majority of the little people seem to be associated with two big people, one of each type, and the really little people spend a lot of time inside then fixed via their mouth to just one type of big person.
RW: I don’t see it.
@JaneSpeakman1@HJJoyceEcon Scientist: If you look at all the other life around these parts, they also seem to be divided into two main groups of body type. This seems pretty universal, now I look deeper. Are you sure this isn’t important?
RW: Ignore it.
@JaneSpeakman1@HJJoyceEcon Scientist: I really think I should consider whether I’ve discovered something fundamental here. Someone might give me a prize.
RW: I think we should group people not according to whether they *have* dangly or undangly bits, but whether they *want* dangly or undangly bits.
@JaneSpeakman1@HJJoyceEcon Scientist: <doubtful look>
RW: Yes, that makes a lot more sense as a categorisation.
Scientist: OK, but I’m going to carry on studying the Danglies and Undanglies. <gets labcoat on and runs after passing Dangly>
@JaneSpeakman1@HJJoyceEcon RW: <calling> Hang on, how do you know that person is a Dangly?
Scientist: <points to dangly bits>
RW: That’s a bit presumptuous though.
Scientist: <bats dangly bits>
RW: What if this person is really an Undangly?
Scientist: <eyes dart between RW and gently swaying dangly bits>
@JaneSpeakman1@HJJoyceEcon Scientist: I’ve discovered something cool about Danglies. Wanna hear?
RW: You can’t call them that.
Scientist: W..what? Do you remember back there when I swatted one of them?
RW: That wasn’t a Dangly.
Scientist: It dangled.
@JaneSpeakman1@HJJoyceEcon RW: That’s not how we recognise Danglies. We recognise them by their internal sense of Dangliness.
Scientist: I can’t see inside their heads.
RW: They don’t have Dangly brains.
Scientists: <backing away slowly> But you clearly have a lot of dangle going on in your head. I’m off.
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Let’s move the discussion from available techniques for sex screening and to matters of process.
Ross @Scienceofsport has described the need for detailed technical documents that inform sports federations in robust implementation of a sex screening policy. I’ll link to his video next.
But here, I’m going to take a wander through running an assay, highlighting standards and procedures.
First, this is Ross’ video of the overall process, highlighting the need for coherent implementation practices. He - correctly - evokes the reams of technical documents used by WADA in their anti-doping programmes.
Even the simplest of lab assays can have pages of instructions associated with it.
So, the assay for sex screening will be detection of the SRY gene. This is the ‘make male’ gene that is the master switch for testes-not-ovaries.
The assays out there are very sensitive and specific. That means they can detect SRY when it’s present, and they don’t give a signal when it’s absent. They aren’t 100% on either metric, but near as dammit.
In 2025, Jon Pike and I argued that exclusion of athletes with androgenising XY DSDs from female athletics is justified, because these athletes are male, not female.
@runthinkwrite This followed a 2024 paper where we, along with Ross Tucker, Tommy Lundberg, Cathy Devine and many others, argued for a return to sex screening to secure eligibility for female sport.
@runthinkwrite @Scienceofsport @TLexercise @cathydevine56 This followed another 2024 paper where we critiqued the (now former) IOC policy on inclusion of trans-identifying males in female sports.
Alvares 2025, n=7, fat mass is higher in females as both absolute and relative values. This is logged as "favours cisgender", which is kinda odd because high fat mass isn't usually considered favourable for sports, but whatever.
TIMS: 16.2 kg (24%). F: 19.5 kg (26%).
But Ceolin 2024 is also logged as "favours cisgender" when their values are:
There are little-to-no controls for physical fitness in the individual studies.
Yet they conclude: “transgender women do not exhibit significant differences in upper-body strength, lower-body strength or maximal oxygen consumption relative to cisgender women after 1–3 years of GAHT.”
You haven’t controlled for fitness!!!
Their "performance" data. Can you see one study that really sticks out as an outlier?
The claim that won't die: trans-identifying males are "underpowered" and therefore "disadvantaged" in sport.
"One can imagine a large car with a small engine competing against a small car with a small engine, and that summarizes the playing field." Joanna Harper, Huff Post, 2016.
"You have a bigger body, and you have a smaller engine to move that vehicle around." Yannis Pitsiladis, BBC, 2019.
"giving trans women the disadvantage of having to power larger skeletal frames with reduced strength and aerobic capacity." Jamie Agapoff, 2025.
What happens when a trans-identifying male suppresses testosterone?
They lose a bit of muscle mass.
Their haemoglobin drops to female-typical levels.
The claim that won't die rests on the idea that trans-identifying males retain their skeletal frame and most of their muscle mass, but become unable to move it around a sports fields, rendering them "disadvantaged".
The words "underpowered" and therefore "disadvantaged" are carefully chosen, and typically leave the reader to infer that this means "underpowered" and therefore "disadvantaged" compared to females.
“Most of the studies used to ban transgender women so far are based on the performances of cisgender men, which scientists have argued is not an appropriate comparison.”
That’s me, @TLexercise and others.
“Others” including the ones moaning about not having their say. You know, the say they took for granted. The one they didn’t tell @nrarmour about.
Ever read their archery paper?
“Other studies have compared the performances of transgender women athletes with sedentary cisgender women, also argued as an inappropriate comparison.”
NGL, bit flummoxed here. Any ideas?
If you want inappropriate comparisons, try the Fat Bloke Study. Written by the scientists moaning about being excluded.
Nancy @nrarmour links to it. Fails to care that the reason why trans-identifying males can’t jump as high as the female comparators is that they are 20kg heavier, carrying way more fat, and are far less fit.
For disclosure, I have not been part of this IOC working group.