The Impact of Gender-Affirming Hormone Therapy on Physical Performance

Abstract

Context: The inclusion of transgender people in elite sport has been a topic of debate. This narrative review examines the impact of gender-affirming hormone therapy (GAHT) on physical performance, muscle strength, and markers of endurance.

Evidence acquisition: MEDLINE and Embase were searched using terms to define the population (transgender), intervention (GAHT), and physical performance outcomes.

Evidence synthesis: Existing literature comprises cross-sectional or small uncontrolled longitudinal studies of short duration. In nonathletic trans men starting testosterone therapy, within 1 year, muscle mass and strength increased and, by 3 years, physical performance (push-ups, sit-ups, run time) improved to the level of cisgender men. In nonathletic trans women, feminizing hormone therapy increased fat mass by approximately 30% and decreased muscle mass by approximately 5% after 12 months, and steadily declined beyond 3 years. While absolute lean mass remains higher in trans women, relative percentage lean mass and fat mass (and muscle strength corrected for lean mass), hemoglobin, and VO2 peak corrected for weight was no different to cisgender women. After 2 years of GAHT, no advantage was observed for physical performance measured by running time or in trans women. By 4 years, there was no advantage in sit-ups. While push-up performance declined in trans women, a statistical advantage remained relative to cisgender women.

Conclusion: Limited evidence suggests that physical performance of nonathletic trans people who have undergone GAHT for at least 2 years approaches that of cisgender controls. Further controlled longitudinal research is needed in trans athletes and nonathletes.

Keywords: body composition; muscle; physical endurance; sport; testosterone; transgender persons.

Figure 1.

Summary of physical performance changes with gender-affirming hormone therapy. + indicates advantage (ie, faster run time or greater number of push-ups) and - indicates degree of disadvantage relative to cisgender comparison group. No difference refers to no statistically significant difference when compared with the cisgender comparison group. ^ indicates data from Roberts et al reporting Air Force fitness test times up to 2 years after GAHT. # indicates data from Chiccarelli et al that expanded analysis for up to 4 years after GAHT.