Thread by @FondOfBeetles

Here is a graphic of changes in muscle and strength in transwomen pre- and post- testosterone suppression (12+ months), compared with baseline metrics from demographically matched females.

The original data is presented in Hilton and Lundberg, 2021 (Table 4).

My coauthor was Dr Tommy Lundberg @TLexercise

link.springer.com/article/10.100…

The graphic was created by me for a policy paper I coauthored with Professor Jon Pike @runthinkwrite and Professor Leslie Howe @usask for the Canadian think tank The MacDonald Laurier Institute.

macdonaldlaurier.ca/biology-fairne…

A consistent theme in response to this data has been to argue that even if transwomen don’t lose very much muscle or strength, it may sufficient to put them within ‘female range’.

Here is a graphic showing the muscle and strength changes pre- (anchored to nominal 100%) and post- testosterone suppression, mapped not just against females (the data already published) but also against control males.

Statistical analysis across the dataset shows there is no significant difference in muscle and strength metrics in transwomen pre- and post- testosterone suppression.

Furthermore, pre-testosterone suppression, transwomen are 7% smaller/weaker than control males and 35% bigger/stronger than females.

Post-testosterone suppression, they are 11% smaller/weaker than control males and 30% bigger/stronger than females.

The argument was: Ok, transwomen may not lose very much, and apparently remain some large percentage ahead of females, but if both TW and females are really different to (control) males at baseline, it’s really just jostling for position in the ‘female range’.

I don’t believe that argument is evidenced in the data. Arguably, we could have run that analysis in our original review. Maybe we didn’t realise that people would start to say that TW were measuring more like female from baseline.

Mea culpa.

It was clear when Tommy and I reviewed the data that transwomen in some (not all) studies were, at baseline, smaller/weaker than control males. This has been, in that literature, attributed to low exercise uptake, comorbid eating disorders etc. I’ve always stated that as a known.

But it’s helpful to see the magnitude of differences and changes in a chart. With some stats.