The paradox in action. Illegal advantage in the 400, legal in the 200. The reason this weirdness exists can be traced back to the CAS Chand decision in 2016, and the “narrow” framing of evidence for the DSD policy, but this situation was inevitable. The events are too similar
Ok, brief explanation. In 2016, the policy for DSD athletes covered all events. Chand challenged it, and CAS said they understood the rationale for the policy, but it required evidence. WA were thus mandated to find the evidence. They tried, but did a poorly conceived study that
…looked for an association between T and performance in each event. They found a positive association in the 400m, 400m H & 800m, and actually a negative on in the 100m! But the policy was thus revised to cover those events, plus the 1500m, as it was deemed similar to 800
It left all other events off, because at the time of the study, no association between T and performance could be found. That’s almost entirely because no DSD athletes competed in those events, which speak to the circular nature of the attempt to find the evidence. In any event,
…the policy was revised and upheld when Caster Semenya challenged it. It leaves this weird paradox where we KNOW that T confers advantages in ALL events, but the policy implies it exists only in some events. Thus an athlete is legal one day, illegal the next, depending on event
The policy did, however, say that in future other events may be added as evidence emerges. Presumably a DSD athlete winning an Olympic medal will constitute “evidence”, but it’s a messy situation, one that appears to target success, rather than principle or physiological theory
Which is strange, because the WA policy that was eventually defended at CAS was exceptional on the physiology and theory. It was very (very, very) weak on the evidence side. Partly because finding this evidence is so difficult, a task set by the legal system that I don’t think
…the scientific one can actually achieve (it was the same, by the way, when Pistorius challenged them for the right to run in carbon fiber blades - the court said “prove the advantage”, and I mean, how do you do that? And that’s actually easier than the DSD one!).
So the way this plays out is that maybe Mboma wins a medal in the future, the same discussion happens as for Semenya, and then authorities have to decide if they have the appetite to try to add the 200m the list of regulated events. Presumably they still can’t add all events, and
…maybe they need specific evidence in the 200m. In which case, I guess they measure T levels & look for performance associations, but with only one athlete there, I’d be surprised if they find it. Or is winning enough evidence (it helped their case that 2016 800 podium was DSDs)

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More from @Scienceofsport

2 Aug
Folks, you can't measure the presence of an advantage by whether someone wins or not. It has to be measured relative to self. The final performance is the SUM of base level PLUS advantage. So looking only at the final says nothing about the presence of absence of an advantage.
For instance, if I competed in the Tour de France with a 100W motor in my bike, I clearly have an advantage. But I still wouldn’t win - my base level is too low. In order to surpass the competition, your base level must be close enough to them that your advantage takes you ahead
The same is true if you use a doping analogy. We KNOW doping improves performance, it is an advantage. But a doper doesn’t always win. Because unless the doper is within the % of their rivals that doping improves then by, their base level will not allow them to win an event.
Read 4 tweets
30 Jul
Mixed 4 x 400m relay heat 1 in Tokyo has just given us a great illustration of sex differences in running (see leg 3 to 4). Based on some discussion here over the last few months, a lot of people need to see this real world illustration. Including, apparently, English commentary
Speaking of the mixed relay, I think it would make the race incredibly exciting if they made teams draw randomly to decide the order of sexes. Imagine a race with some teams going MMFF, some FFMM, some MFFM, or MFMF etc. That race would be suspenseful and hugely unpredictable

Here’s a handy little toolkit for that mixed 4 x 400m final. Top 2 qualifiers (or heat winners) get to select their order. The other 6, you just cut these little strips up, and make the teams draw from a hat. I promise it’ll be super exciting the whole way! 👍🏼
Read 4 tweets
29 Jul
On transgender women & performance advantages. One thought - isn’t it astonishing that given “lots of aspects…physiology & anatomy & the mental side”, that NO female has EVER come within 10% of the best 1000 males?

Or…is this an irrelevant distraction given that BOTH males...
…and females already possess the physiology & mental side necessary to be champions within their respective characteristics? So what is the source of the huge gulf in performance?

This is, in fact, the most direct journey to saying a women’s category is not necessary in sport
That is, if elite performance is a result of "a lot of aspects", we can crown a single “human” champion in all events

But where are women among the top 1000 humans in the world right now? Is it a co-incidence that they never have these aspects?

Or…maybe they’re different?
Read 7 tweets
21 Jun
@tomhfh I can assure you that I am not the one who is confused. Let’s take weight - a weight class exists for boxing in BOTH men AND in women. Why is that? What would happen if we mix the sexes at the same weight? So again, let me ask, since you feel you know this: How would you do it?
@tomhfh Let’s take the first step. We use weight. We say that a male at 70kg should be accepted into women’s sport at 70kg. Now we discovered that this male is 34% stronger than the weight-matched female. Now what? We have to screen for strength, is that right? How do we do this in a
@tomhfh …credible and valid way? Which tests would you use? What about punching power, which is 260% higher in males? Even if that is adjusted for mass, it stays say 150% higher. Which test might be conducted to match those together? Now think about speed - males are 10-15% faster than
Read 10 tweets
15 Jun
A summary of the CAS decision is now available:… It doesn't tell us anything that couldn't already be deduced - we know that they ruled that Houlihan failed to establish the source of the nandrolone. That's why she got 4 years. The details are key & absent
It’s been a day full “I choose to believe” statements. I can’t believe how many people’s reaction is “the system must be screwed up, she’d never dope”, having heard literally only one side of the story. It still strikes me as remarkable how specific her statement is, and the...
…”proof” she has claimed was presented to CAS in her defence includes a polygraph, a receipt, phone location records, hair samples, and STILL CAS has ruled that she failed to reach a “balance of probability”. Surely you should be asking “What am I missing from the OTHER side”?
Read 4 tweets
15 Jun
On the Shelby Houlihan doping ban, it would be interesting to see details & the strength of what was deliberated at CAS (and by whom) from the AIU side. Houlihan suggests in her statement that “anti-doping experts agree with me”. Clearly, that’s not entirely true. One of many Qs
Also, find other doping cases with the same contaminated food/supplement explanation and check the reactions. The suspicious side-eye, a knowing “hmmm, I bet”. Now many of the same people are saying “hang on, are we sure testing is OK, it seems unfair, I believe Shelby & Jerry”.
I will say, however, late-career improvements are suspect every time (and if you list the half dozen reasons, just remember them when it’s a Kenyan or Russian, ok?). Also, other athletes with this excuse often get reduced sanctions (or none!). A 4-year ban suggests confidence
Read 4 tweets

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