A Study on The Impact of Gender-Affirming Hormone Therapy on Physical Performance

 Bookmarking this 2023 study as the issue of transgender women participating in women's sports continues. The Summary and Conclusions section of the study is below:

Summary and Conclusions

As trans people have been stigmatized for many decades, there is little research in the field and the evidence base is not definitive. Our understanding of the impact of GAHT on physical performance is based on retrospective data with no prospective longitudinal controlled studies. Further research is underway (125).

Existing studies in nonathletic trans men have shown that increases in muscle mass and strength occur with testosterone therapy, and physical performance appears to be no different to cisgender men by 1 to 3 years after GAHT.

Studies in nonathletic trans women after GAHT demonstrates no change in height, but have shown decreases in hemoglobin, bone density compromise, and decrease in muscle mass and strength, which continue to decline beyond 2 years. While absolute muscle mass is higher, their relative muscle and fat mass percentages and muscle strength corrected for lean mass are no different to cisgender women. Cross-sectional studies of trans women on GAHT for over 4 years show that relative percentages of muscle mass and fat mass as well as fitness as measured by VO₂ peak corrected for lean mass are no different to cisgender women and lower than that of cisgender men. Steady decrements are seen in physical performance of nonathletic trans women in the military, with no significant difference with cisgender women for running times by 2 years and sit-ups by 4 years after GAHT. An advantage in push-ups or upper body strength over cisgender women may remain at 4 years.

The limited existing research should be interpreted considering sports-specific factors; different combinations of physical capabilities including upper or lower body muscle strength, hand grip strength, endurance, power, flexibility, hand–eye coordination, communication with teammates, mindset, and strategy may or may not be relevant. Consideration of existing research will be part of the process in creating policies for the inclusion of trans people in elite sport. Reasonable accommodations for the inclusion of trans people are sport specific and could be based on the range of competitive advantages and abilities that are already accepted in the cisgender population.

Although prospective longitudinal controlled studies in trans athletes are needed, with so few trans athletes and extremely low participation of trans people in sport, recruitment into such research will be challenging. Future research should include larger sample sizes of trans people (nonathletes and athletes) to be compared with cisgender males and females with relevant outcomes adjusted for known confounders.