Thread by @RaskinSalmo

IS THERE ENOUGH SCIENTIFIC EVIDENCE THAT FEMALE TRANSGENDER ATHLETES ON TESTOSTERNE SUPRESSION HAVE A COMPETITIVE ADVANTAGE IN OLYMPICS? 🧵🧵🧵👇👇

When I first read the IOC announcement of the new policy regarding female athletes screening genetic tests, my first thought as a Medical Geneticist was that it would be complex to apply, based on current scientific knowledge and evidence based medicine, for 46,XY female athletes

And that the police would be straightforward for female transgender athletes, as they should have a competitive advantage.

But reviewing the scientific literature, I see that this not so clear. I selected what I believe are the main scientific articles defending two diferent visions;

Ones that defends that the muscular advantage enjoyed by transgender women is only minimally reduced when testosterone is suppressed, and others that defend that there is not enough scientific evidence of inherent athletic advantages for transgender women over cisgender.

Starting with defensors that there is no proof of athletic advantages for transgender women over cisgender, I selected a few publications that reach similar conclusions; while transgender women exhibited higher lean mass than cisgender women, physical fitness was comparable👇

One is a 2026 systematic review with meta-analysis
pubmed.ncbi.nlm.nih.gov/41633803/

The second is a literature review
pubmed.ncbi.nlm.nih.gov/37437247/

and the third one is the paper by 2020 Hamilton B
pubmed.ncbi.nlm.nih.gov/37726582/

And there are also many publications defending that the muscular advantage enjoyed by transgender women is only minimally reduced when testosterone is suppressed, papers mainly from Emma N Hilton, Tommy R Lundberg and Ross Tucker @Scienceofsport

pubmed.ncbi.nlm.nih.gov/33289906/

pubmed.ncbi.nlm.nih.gov/37726583

onlinelibrary.wiley.com/doi/full/10.11…

pubmed.ncbi.nlm.nih.gov/33648944/

pmc.ncbi.nlm.nih.gov/articles/PMC12…

and the book Testosterone: The Story of the Hormone That Dominates and Divides Us by @hoovlet

My opinion is that we need more high‐quality scientific prospective longitudinal data regarding sport performance advantage of female transgender athletes over cisgender athletes, to understand both the extent of testosterone suppression across different GAHT regimens .........

....... and the duration required to meet eligibility guidelines for participation in women's sports. And that participating in diferente sports should have diferente guidelines.

Guidelenes for boxing, rugby and runners should be different that the ones for precision sports like shooting and archery where skill, accuracy, and mental focus outweigh physical strength and power. In Equestrian competition in Olymplics 46,XX and 46, XY compete together.

Finally, I understand that better knowlege will be avilable when trials such as the GAME study (the effects of Gender Affirming hormone therapy on skeletal Muscle training and Epigenetics) finish.

This study is a prospective age-matched cohort study in transgender adults commencing GAHT (n=80) and age-matched individuals not commencing GAHT (n=80), conducted at Austin Health and Victoria University in Victoria, Australia.
pubmed.ncbi.nlm.nih.gov/35545400/

But what has to be done right now?? Allow female transgender to compete with cisgender females until we have a clear scientific answer, or banish them until science give us undoubtful answer?

And you, do you have a formed opinion on the competitive advantage of transgender female athletes that have Testosterone supression?

@threadreaderapp please unroll!