Up front it is worth mentioning that there has yet to be a case of a transgender female dominating in powerlifting. However, in olympic weightlifting Laurel Hubbard was somewhat dominant, and Cece Telfer won the NCAA women’s track national championship.

While the USAPL regulation to ban transgender athletes from competing may appear hostile, they are at least consistent in that they do not allow men with low testosterone on TRT to compete. Which is just to say the exogenous hormones, regardless of why they are taken, are not tolerated.

The evidence backing the International Olympic Committee (IOC) policy to allow transgender athletes to compete:

• It was based off of just 2 studies by Joanna Harper (the first of which did not look at elite athletes). The second study looked at cycling, running, and rowing with a total of 8 athletes included wherein no descriptive statistics were run.
  
• All data was self reported over 5 years, and the study failed to control for variables including training history, injury, diet, weight, body composition, and mental health, nor were they provided.
  
  

The evidence against transgender athletes competing against biological women:

• In rodent studies mice that were given testosterone and trained performed better than the control group which was unsurprising. When the testosterone was taken away and a wait of 10% of their lifespan occurred the differences in results for training were still statistically significant (31% growth in muscle cross-sectional area vs 6%).
  
• Human biopsies have shown that muscle nuclei count remains elevated event after the removal of testosterone. Any male puberty confers an immutable competitive advantage.
  
• In a survey of 17.351 lifters over 7 years (6351 female, 11000 male) men were shown to have a 64% advantage in international open class and a 46% advantage if using overall mean.
• Anti-androgens appear to decrease performance by 10%. Reducing a 64% advantage by 10% is not adequate for “fairness”.
  
• Given the advantage conferred by steroids is understood to be ~10%, a woman on steroids would still be at a disadvantage to a transgender women on anti-androgens.
  
• Spironolactone is the most common anti-androgen in the US and is a masking agent for testosterone. This means spironolactone needs to be removed 5 days prior to competition during which the testosterone will bounce back to some degree and continue to confer an advantage.
  
  

In short, the problem is complex. I’ve laid out a small portion of the arguments in the debate. For a fuller overview which leans towards allowing transgender women to compete in women’s categories I would recommend Jordan Feigenbaum’s article.