Assessing Hormone Therapy's Effects on Transgender Women's Athletic Performance

A recent study conducted by Loughborough University provides insights into how gender-affirming hormone therapy (GAHT) influences the athletic capabilities of transgender women. This research is particularly pertinent given the ongoing debates around transgender participation in sports, where physiological differences often influence competitive fairness. Typically, sports are divided by gender to account for variations in endurance, strength, and overall athletic performance, primarily due to differences in testosterone levels following puberty. Higher testosterone levels in males contribute to increased height, muscle mass, hemoglobin levels, and larger cardiac and lung capacity.

Despite increasing visibility and participation of transgender athletes, the impact of GAHT on performance remains underexplored. The study analyzed data from nine transgender women runners and one swimmer, tracking their performances before and after initiating hormone therapy over a 12-month period. Data collected included race times, training volume, physical measurements, and hormone levels, with the goal of understanding how GAHT affects athletic outcomes.

The findings revealed that, on average, the performance of the runners declined by about 15%, while the swimmer's times slowed by approximately 5%. Notably, performance decrements were more significant in longer-distance events. Researchers suggested that training volume played a role, with higher training loads somewhat mitigating performance loss post-GAHT. Hormone levels of participants were successfully brought within typical female ranges.

Expert commentary indicated that the effects of GAHT on athletic performance are complex and may vary depending on the sport and training intensity. Shorter events emphasizing strength and power appeared less affected than endurance sports like middle- or long-distance running. The study aligns with prior research reporting modest strength reduction after 36 months of therapy and decreased hemoglobin within four months, impacting endurance capacity. However, limitations such as small sample size and varying participant backgrounds necessitate cautious interpretation.

This emerging area of research underscores the need for more extensive studies to inform policies and ensure fair competition in sports as more transgender athletes participate at competitive levels. Further evidence is essential for sports organizations to develop inclusive and equitable guidelines grounded in scientific data.