The Study
Longitudinal Performance Changes in Transgender Women Athletes Pre and Post Gender Affirming Hormone Therapy
This study watches a small group of transgender women athletes over time to see how their race times and training change after starting hormone therapy. It can show patterns or links, like 'when training went up, performance stayed better,' but it can't prove that the hormones caused the changes because many other things could have affected the results.
Analysis score
Maximum 72 for a cohort study.
Where the score came from
This study looked at how hormone therapy changes how fast transgender women run and swim by comparing their race times before and after treatment.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 544 / 100
Quality score
Groups of people are followed over time to see who develops an outcome. Strong for identifying risk factors and associations, but cannot prove causation as firmly as RCTs.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes, the results are meaningful: hormone therapy reduces athletic performance, especially in endurance events, but training can help reduce the loss.
- 2The athletes remain similarly competitive in the women’s category.
- 3After hormone therapy, runners were about 15% slower on average.
- 4Long races slowed more than short ones.
- 5One swimmer was 5% slower.
- 6Testosterone dropped to typical female levels.
- 7Even though times got slower, they stayed just as competitive in their age group.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
European Journal of Sport Science
Year
2025
Authors
Joanna Harper, R. Blagrove, E. Hunsicker, G. Witcomb, R. Ferguson, E. O’Donnell
Related Content
Claims (6)
Trans women athletes on hormone therapy see their testosterone drop to typical female levels after about 5 months, which shows the treatment is working to lower male hormone levels.
Trans women athletes tend to slow down more in long races after hormone therapy than in short sprints—suggesting endurance is affected more than quick bursts of power.
Transgender women runners stay about as competitive in their age group after starting hormone therapy, even though their actual race times slow down a bit.
Trans women runners get slower over time after starting hormone therapy, especially in longer races — their race times go up by about 14-17%, while sprints are less affected.
For transgender women runners, boosting their training might help maintain their running performance after starting hormone therapy.
Trans women on hormone therapy might not jump as high as cis women.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.