How Does Hormone Therapy Affect Transgender Women Athletes' Running and Swimming?
Longitudinal Performance Changes in Transgender Women Athletes Pre and Post Gender Affirming Hormone Therapy
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
One swimmer got slower but more successful.
Even though her race times slowed by 5.2%, her FINA score—a measure of competitive success—improved by 65 points, meaning she became more competitive in the women’s category than she was in the men’s.
Practical Takeaways
Trans athletes can preserve performance by increasing training volume after starting hormone therapy.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
One swimmer got slower but more successful.
Even though her race times slowed by 5.2%, her FINA score—a measure of competitive success—improved by 65 points, meaning she became more competitive in the women’s category than she was in the men’s.
Practical Takeaways
Trans athletes can preserve performance by increasing training volume after starting hormone therapy.
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.