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 is comprised of cross-sectional or small uncontrolled longitudinal studies of short duration. In non-athletic 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 non-athletic trans women, feminising hormone therapy increased fat mass by approximately 30% and decreased muscle mass by approximately 5% after 12 months and steadily declined beyond 3 years. Whilst 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. Whilst push-ups performance declined in trans women, a statistical advantage remained relative to cisgender women. Conclusions Limited evidence suggests that physical performance of non-athletic 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 non-athletes.

Sex differences and athletic performance. Where do trans individuals fit into sports and athletics based on current research?

“…Trans women were also shown to have higher grip-strength than cis women (93.0 ± 14.0 kg vs. 63.9 ± 9.5 kg) with no difference from cis men (112.7 ± 23.2 kg) ( 35 ). These findings do align with other studies that find strength and muscle mass do not adapt as quickly to gender affirming hormone therapy as cardiorespiratory parameters ( 14 , 16 , 54 , 127 , 129 ). However, on more performance related tests of: vertical jump height, pushups, and maximal aerobic capacity, trans women performed similarly to, or less than, cis women (33.98 ± 4.34 cm, 17.83 ± 5.46, and 29.43 ± 9.41 ml/kg/min compared to 34.24 ± 7.84 cm, 19.67 ± 11.64, and 30.43 ± 9.15 ml/kg/min), and significantly less than cis men (47.34 ± 6.43 cm, 48.0 ± 5.37, and 41.15 ± 13.77 ml/kg/min) ( 53 ).…”

“…Based on these data, trans men and trans women continually performed more similarly to their affirmed cisgender performance averages, and approach their own pre-transition percentile scores over the four years of gender affirming hormone therapy (129). Although these findings seem to indicate that trans individuals may eventually reach equivalence with their cisgender counterparts, it should also be noted that the participant pool diminished over the four years of follow-up, increasing the risk of self-selection bias and increasing risk of potential error (14,129).…”

“…(1) Transgender individuals on gender affirming hormone therapy should not be equated to their pre-transition cisgender counter parts. Gender affirming hormone therapy can alter physiologic parameters (12)(13)(14)(15)(16). Thus, transgender individuals must be directly measured rather than assuming cisgender sex differences are analogous to cisgender and transgender differences.…”