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The UCI's Scientific Smokescreen

UCI's Scientific Smokescreen

World Rugby were the first, but now FINA (swimming) and International Rugby League have followed in making women’s sport open only to women, or at least to anyone who hasn’t undergone male puberty. International cycling body the UCI have also produced a new transgender policy[1]. The policy extensively quotes the scientific literature, but does the science back up the policy? Let’s see.

The UCI start by defining sex as biological and gender as fluid and sociocultural, which sounds like a good start. They then claim performance differences exist between ‘genders’, suggest that trans people don’t fit into biological sex categories, and introduce the term ‘cis’, none of which clarifies the situation.

They then present a large amount of data, quoting from various scientific papers. Overall the data they present is this, all referenced to research:

In cycling, men perform better than women: approximately 9-16% better in track cycling and 13-14% in road cycling, and for all cycling disciplines, performance is based on both endurance and muscle strength.

They state: “there are large baseline differences in muscle mass between males and females, with differences of 54%, 48% and 64% in total skeletal muscle mass, lower body muscle mass and upper body muscle mass, respectively

They look at muscle size and what happens when males suppress testosterone and find that 12 months of testosterone suppression to female levels results in 3 to 5.4% loss of muscle, but with maintenance of muscle strength in the large muscles of the thigh, and report that studies have shown a maximum loss of 17% muscle after an average of 8 years. They are clear what this means and state “the results of this experiment suggest a retained physical advantage in TransWomen, even after 8 years of testosterone suppression”.

It's clear that muscle strength advantages persist, but what about the other component of cycling performance: aerobic endurance? After looking at the evidence they conclude “The treatment-induced reduction in the oxygen-carrying capacity reported in TransWomen has very likely negative consequences on endurance performances, estimated at -2 to -5%”. Since we know from other research that males are around 10% faster than females in running events, where performance is heavily weighted towards aerobic capacity and less towards muscle strength, this reduction doesn’t look like enough. This is borne out by a study of transgender military personnel which showed transwomen were still 12% faster than females in a running test after 2 years of testosterone suppression[2].

The evidence the UCI present shows neither muscle mass and strength, nor aerobic performance, reduces to female levels after 2-8 years of testosterone suppression. The UCI state “It would be reasonable therefore to allow transgender to compete with other female athletes if their inclusion guarantees fair and meaningful competitions”

It’s clear from the evidence that fair competition can’t be guaranteed if males are allowed to compete with females, even with testosterone suppression.

It might seem at this point that the UCI are about to go the same way as World Rugby, but the report does give us some pointers about what’s going to happen next. In one part of the report they admit that the effects of testosterone during puberty is the most important determinant of athletic performance, but then include a seemingly irrelevant paragraph about adult female athletes with slightly higher (but female range) testosterone having slightly better performance in some studies than those with lower (but female range) levels, which says nothing about the fact that normal adult male levels are at least 5 times higher than in females, and ignores the effects of puberty. They conflate sex and gender at the start and try to imply that transgender people aren’t either male or female, when they are. Now they decide to introduce a new definition of “fair” by saying

“It may not be necessary, or even possible, to eliminate all individual advantages held by a transgender. It is paramount, however, that all athletes competing have a chance to succeed, albeit not necessarily an equal chance.”

Having clearly shown that transwomen retain an advantage they now get rid of the “guarantee of fair competition” they claimed to adhere to by throwing fairness out of the window, and produce a policy that says transwomen need to show suppression of testosterone levels to 2.5 nmol/L for a minimum of 2 years.

So how have the UCI arrived at a policy which is contradicted by the evidence they themselves have cited? Is it because they are scientifically illiterate, because they are stupid, because they are misogynists, is it more than one of these? What’s clear is that the UCI seek to continue to disadvantage women and are happy to pervert science to do this. They think they can use science, not to inform, illuminate and guide an evidence based policy, but as a smokescreen to hide behind. They think quoting a lot of data will make everyone believe their unscientific and unfair policy is backed up by evidence. They are wrong.


2. Effect of gender affirming hormones on athletic performance in transwomen and transmen: implications for sporting organisations and legislators

Timothy A Roberts, Joshua Smalley, Dale Ahrendt

Br J Sports Med 2020;0:1–7. doi:10.1136/bjsports-2020-102329



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