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21. Effect of Gender Affirming Hormone Therapy on Athletic Performance: A Four Year Follow Up Study

      Purpose

      The effects of gender affirming hormone therapy (GAHT) on athletic performance past 24 months of treatment have not been quantifiably demonstrated. Identification of expected trends in performance is significant for transgender individuals’ participation in competitive sport. World Athletics and the International Olympic Committee guidelines require female athletes to demonstrate testosterone levels of less than 5 -10 nmol/L respectively for 12 months preceding competition; only limited data have been gathered to demonstrate performance changes past this timeframe. Recent policy changes in the United States military allowing transgender members to serve presents an opportunity to evaluate longer term outcomes.

      Methods

      The Department of the Air Force uses a centralized clinical approach to gender transition. Air Force transgender patients were identified using the Air Force’s multi-disciplinary care team database. GAHT initiation date was recorded, as well as comparison values for the Air Force Physical Fitness Test (PFT) components prior to and up to four years following GAHT initiation. Scores were categorized by year after GAHT initiation. The Air Force PFT performance measures are maximum number of push-ups and maximum number of sit-ups in 1 minute, and a 1.5 mile run time. Pre- and post-GAHT scores were compared by one-sample T-test to mean scores of Air Force wide cisgender averages for servicemembers aged 20-30 with p<0.05.

      Results

      The sample included 374 patients, 146 transgender men and 228 transgender women with a mean age of 26 at GAHT initiation. Forty-three patients completed follow up to at least 36 months. Prior to GAHT, transgender males demonstrated better performance compared to cisgender females in push-ups, sit-ups, and run times (p<0.001). Compared with cisgender males, they performed worse in all events (p<0.001). Following initiation of GAHT, transgender men approached statistical equivalence with cisgender men in the sit up event at 1 year, while push-ups and run times took 3 years to equilibrate. Before GAHT, transgender females demonstrated worse performance in push-ups compared to cisgender males (p<0.001) but were not significantly different in sit ups or run times. Compared with cisgender females, they demonstrated better performance in all events (p<0.001). Following initiation of GAHT, transgender women performed significantly better than cisgender women at 1 year in all tested events (p<0.001). Transwomen’s performance approached statistical equivalence with cisgender women at 2 years of GAHT in run times (p=0.07), sit-ups at 3 years (p=0.34), and were not equivalent in push-ups at the study’s 4-year endpoint (p=0.02).

      Conclusions

      In a sample of Air Force adult transgender patients, athletic performance measures change heterogeneously with respect to affirmed gender following GAHT. This highlights the need for continued study into transgender athletic performance and suggests that current guidelines may be incomplete.

      Sources of Support

      Roberts TA et al. Effect of gender affirming hormones on athletic performance in transwomen and transmen: implications for sporting organizations and legislators. British Journal of Sports Medicine, 2021 Wiik A et al. Muscle strength, size and composition.