Ross Tucker Profile picture
Sports science, insights, opinion. One half of The Science of Sport podcast - @sportsscipod Follow & support at
dniklasd Profile picture Liz Panton #WomensRightsAreHumanRights Profile picture Render Monkey Profile picture Espen Aareskjold Profile picture Alan Boydell Profile picture 12 added to My Authors
Jun 22 31 tweets 15 min read
Rugby’s Return to Play protocols after concussion - yesterday, @WorldRugby announced some changes to the management of players after concussion. You can read it here:… And here’s a thread on some of the process & science behind it, which I was involved in @WorldRugby To begin with, let’s look at what happened in the past. First, there used to be a mandatory stand-down period - a concussion meant that player couldn’t play again for an agreed, pre-determined period (it was still open for case by case exceptions, though). Then that was replaced
Jun 22 13 tweets 3 min read
Let’s think this through (hint, reader - we have thought this through, a lot. It’s been 3 years of grappling with the issue). First problem - physiology. What do you test, and how, in order to approve a TW as not having an advantage? Do you measure performance as the outcome? (1/ If you do it by performance, how do you control for deliberate under-performance? Also, performance is the point of sport, so you’d be using the outcome as the input, so that you’d have a chance at an outcome? That is, well, perfectly circular and defeats the point of sport (2/
May 12 6 tweets 2 min read
I’m rarely a glass half-full person! But in a weird way, the weakly argued & deeply discriminatory article linked to below represents a kind of positive shift in this debate. It used to be argued that there was no unfairness, that we could include AND be fair at the same time 1/ But now, even the most obvious attempt to include TW at the expense of fairness (& safety - same source physiology) for women has had to abandon this “fairness deception”, and must now begin by accepting the retention of advnantage. It may not feel it, but that IS progress.
May 9 5 tweets 2 min read
I shouldn’t be amazed at the objections in the letter, but we really are in a bizarre place. The “dance” continues. Used to be “women had no problem with it, so what’s the issue?”. Then women got asked, so now they have to reject HOW they’re asked, including a sidestep of reality Which means having to dictate which words can & can’t be used when asking people’s opinions. This is required to sidestep biological reality (“male”), which then denies ever allowing women to express a direct opinion on the very thing they’re being asked to express an opinion on
Mar 25 5 tweets 2 min read
Words like “fear”, “prejudice”, “hysteria” and “hateful” imply that concerns about Women’s sport are irrational and illegitimate. You can only make this allegation if you think it’s unreasonable for women to want a space in sport that excludes male advantage. So, is it? Given a) the significant effect of male biology on performance, and b) the performance differences between M & F, it’s clearly not unreasonable for women to want this. In fact, it’s rational and necessary. For them to then to told to accept it for a range of reasons including…
Mar 24 9 tweets 33 min read
@oldJavaGuy @wutangclown @Hogshead3Au @Martina @PlaceSteph @Phildidgee @CarlBrownisback @sharrond62 @FondOfBeetles @bladderwracked @tgivensdotcom1 @SwimmingWorld @Caitlyn_Jenner @coachblade @runthinkwrite @andyturner110h @BUCSsport I remember that thread, it got a lot of discussion at the time. It’s talking about the DSD cases, which is a very different issue from trans women/men, and doesn’t really offer insights into what is actually typical biological sex. however, if one wants to talk about DSDs, then @oldJavaGuy @wutangclown @Hogshead3Au @Martina @PlaceSteph @Phildidgee @CarlBrownisback @sharrond62 @FondOfBeetles @bladderwracked @tgivensdotcom1 @SwimmingWorld @Caitlyn_Jenner @coachblade @runthinkwrite @andyturner110h @BUCSsport …they too are relatively straightforward - what happens is atypical development of the primary sex characteristics, but the individuals with DSDs are still biologically male or female. The distinction is based on gametes (see anisogamy) and this thread deliberately avoids that
Mar 18 25 tweets 5 min read
The Lia Thomas result last night is pretty straightforward - confirmation of hypothesis. Based on the physiology, it was predictable that a male athlete with sufficient base level athleticism would suppress T, retain enough physiological advantage & thus performance, to win (1/_ At a recent debate on this issue, Malcolm Gladwell raised that legal concept that “hard cases make bad law”, which can be applied in some instances, but here, works the opposite way around - this is a case that is entirely the result of bad “law”, or policy. A policy that…
Mar 5 13 tweets 4 min read
This was my primary frustration after today’s debate on the subject at #SSAC22 Hard as I tried to explain that every SELECTION matters, that every place or lane earned by a girl or woman going a male is wrong, what this debate needs is for women to be asked for their voice The reason this came up, by the way, is that @gladwell asked the panel if this issue of trans women participation could be handled differently for elite sport compared to sub-elite and community sport? One answer was that yes, it can and should be, and only when records & money
Mar 4 4 tweets 2 min read
The next session at @SloanSportsConf is on Title IX, which, according to the programme, is “a law rooted in equal opportunity and prohibiting discrimination based on *sex*”. Perhaps the panel will explain when and how this changed, to the detriment of Women’s sport… The Massachusetts AG just said “this law was significant because it was the first to ban discrimination based on sex”. Everyone KNOWS it’s based on sex. This is why conflating sex with gender is a necessary tactic to discriminate against women. It breaks the law otherwise
Feb 18 5 tweets 2 min read
Here are the 50-yard splits from the medalists in the women’s 500-yard freestyle final at the Ivy League champs. A 15-year old pool record was broken. Pacing strategy 101: Which of these patterns suggests a significant reserve capacity and likely underperformance? If you said, gold, you’d be right. In events lasting longer than about 3 min, negative pacing strategies and the characteristic endspurt (where we speed up at the end) are suggestive of someone who has maintained a reserve, producing a controlled effort below max for the race
Feb 11 4 tweets 2 min read
So RUSADA lifted the provisional suspension after a positive test for medication used to treat angina. In a 15-year old. Who’d have thought that RUSADA, who oversee anti-doping for “Not Russia” (because of doping) might do such a thing? Can’t wait to hear what comes out at CAS. The question is how does a 15-year old get hold of and use trimetazidine? Will they claim contamination at a pharmacy? Wrongly prescribed drug by a doctor? If ever there’s a case to throw everything at the entourage, this might be it. Or…they can “sacrifice" the teenager
Feb 2 4 tweets 1 min read
Much will depend on how they apply this clause. One reading of it, as per Jon below, is that TW will have to provide evidence of NO advantage, which, *if* the scientific evidence is applied honestly, would not be possible, so it would achieve the appropriate protection of F sport An alternative approach will be if the scientific evidence showing retained advantages is relegated to “part of a bigger picture”, which also ignores fundamental biology, & instead they try to use a case by case approach, which would be murky and likely NOT achieve fairness.
Jan 21 23 tweets 4 min read
I want to try to explain something about testosterone and performance, since it has become the ‘fixation’ and the ‘the fix’ for inclusion policies for both DSD and trans athletes. So here’s a thread to ‘debunk’ and explain why T level, per se, is not quite the right place to look First, testosterone is clearly a significant driver of the biological, and hence performance, differences between M and F. Nobody should dispute that (yet they do - more on this later). What sport has done, understandably, is to try to capitalise on this “cause-effect” concept to
Jan 20 4 tweets 1 min read
Michael Phelps, whose biological traits fall within norms for the men he swam against, recognises advantages of trans swimmers who retain many biological male traits

Remember. Advantages DO matter if they cross category boundaries. Sport does not exist to celebrate testosterone Just like boxing does not exist to reward size/mass Paralympics do not exist to reward the absence of disability, and youth sport does not exist to reward maturation. We separate groups into categories/classes so that we can reward what is meaningful, unconfounded by what is not
Dec 28, 2021 4 tweets 1 min read
Interesting thing about this argument (which tries to turn the desire to protect women’s sport into some kind of disparagement of women) is the irony that it’s only a CLEAR separation of the sexes that allows us to celebrate athletic achievements of women. It’s only when we (1/ …blur the lines and try to deny biological realities that we invite direct comparisons between male and female performance (which, in a further irony, is the premise for the necessary separation!) that women’s sport is undermined. For instance, nobody should have an issue (2/)
Nov 19, 2021 6 tweets 3 min read
Our latest podcast is out, and in it, we discuss the IOC’s transgender guidelines. Here’s a short video segment, “First reactions”. You can listen to the full episode here (or wherever you get your pods!)… The missing truth: aside from the deception of saying “no presumed advantage”, the missing piece is a simple statement of biological fact that trans women retain advantages even after T suppression (let alone without it). This omission can only be due to political influence.
Oct 1, 2021 11 tweets 10 min read
Rather than write a long thread, here’s a podcast or an instagram video with my thoughts on yesterday’s Sports Council transgender guidelines, what they say, imply, confirm, and mean for the future:…

Or the insta, if preferred:… One thing I discuss in the podcast is the appalling issue raised by the report, which is fear of recrimination that has been created for those (particularly women) who speak out with concerns about fairness & safety. That they’re backed by scientific evidence has been irrelevant.
Sep 23, 2021 18 tweets 6 min read
So, @WorldRugby has released guidelines for contact load during training in elite rugby. You can read the full document and a summary infographic here:… I wanted to share brief thoughts on the process & principles behind the guidelines, so here goes... @WorldRugby First, the need. Research has found that training injury risk (in terms of incidence, or injury risk per 1000 hours) is relatively low, BUT…because training volume is so high, a large number of injuries happen in training. And full contact training has the highest risk. So the
Aug 18, 2021 10 tweets 4 min read
@SUE_K47 Yes I saw it. And it’s important that the research be recognised as flawed (in some respects, faulty) & limited. But I don’t see this as the bombshell Roger is claiming. the DSD policy has two components - the evidence around specific events (which is what the paper did so badly @SUE_K47 …and second, the principle regarding androgenisation in males, not females, that necessitates a separate competition. I think everyone at CAS already knew this about the research - it was discussed at great length there. From the flaws to the theoretical problems. The IAAF even
Aug 4, 2021 11 tweets 5 min read
@DesiFootyStats It’s different by scale (a lot) and concept. First, scale. Phelps was about 0.2-0.4% better than his rivals. Indeed, he even lost races. His “advantage” was worth about half an arm length. Compared to the male vs female advantage, that’s tiny. M vs F is about 10-12%, so Phelps @DesiFootyStats …would be about FIVE body lengths ahead of Ledecky or McKeown. The M vs F difference is enormous, way way bigger than anything that exists within males because of long arms or whatever other simplified theory one has for why an athlete wins.

Next, let’s talk concept.
Aug 2, 2021 4 tweets 1 min read
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