Introduction: Transgender individuals have served openly in the U.S. Military since 2016. Official policies for transgender servicemembers continue to evolve, including approaches to physical fitness testing of transgender servicemembers. There is a paucity of scientific data regarding the effects of gender affirming hormone therapy (GAHT) on athletic performance for the past 24 months of treatment. Identification of expected trends in performance during and after gender transition is essential to allow for the development of appropriate military policy regarding when to assess servicemembers' fitness by standards of their affirmed gender.
Materials and methods: We identified Department of the Air Force transgender patients using the Transgender Health Medical Evaluation Unit database and recorded dates of GAHT initiation through a retrospective chart review. We recorded performance values for the Air Force physical fitness test components 1 year before and up to 4 years after GAHT initiation. Performance measures were maximum sit-ups in 1 minute, push-ups in 1 minute, and 1.5-mile run time. Pre- and post-GAHT scores were compared using one-sample T-test to mean scores of Air Force-wide cisgender averages to assess for significant difference between affirmed transgender and cisgender airmen. We then performed the two one-sided test (TOST) procedure for equivalence with upper and lower bounds set at 1 SD from the means for cisgender airmen. Finally, using Z-scores, average transgender group scores were assigned a percentile rank with their respect to affirmed gender throughout the transition process.
Results: Following initiation of GAHT, transgender males demonstrated statistically significant worse performance than cisgender males in all events until 3 years of GAHT. Their average scores would have attained a comfortable passing score within 1 year of GAHT. Transgender females' performance showed statistically significantly better performance than cisgender females until 2 years of GAHT in run times and 4 years in sit-up scores and remained superior in push-ups at the study's 4-year endpoint. TOST confirmed equivalence at all points where statistical difference was not demonstrated. Servicemembers approximate their pre-GAHT assigned gender percentile ranking in their affirmed gender in a manner consistent with hypothesis and TOST testing in the push-up event for both transgender males and females and in the 1.5-mile run event for transgender males.
Conclusions: In a sample of Air Force adult transgender patients, athletic performance measures demonstrate variable rates of change depending on the patients' affirmed gender and differ by physical fitness test component. Based on this study, transgender females should begin to be assessed by the female standard no later than 2 years after starting GAHT, while transgender males could be assessed by their affirmed standard no earlier than 3 years after initiating GAHT.
Published by Oxford University Press on behalf of the Association of Military Surgeons of the United States 2022. This work is written by (a) US Government employee(s) and is in the public domain in the US.