Testosterone and Transgender Athletic Performance :
Finding a path for transgender inclusion

Testosterone and female sports

Participation in exercise and sports has many health benefits and all people should have the opportunity to participate. After puberty, testosterone gives male athletes competitive advantage over female athletes. Because of this advantage, many sports are segregated by sex at birth to ensure fairness in competition. However, this sorting does not account for women with naturally elevated levels of testosterone or prior exposure to testosterone. To address this problem, sporting organizations, such as World Athletics or the International Olympic Committee, have tried to establish guidelines for inclusion of both women with medical conditions that result in elevated testosterone and for transgender women in female sports. The most recent recommendations have included maintaining serum testosterone levels in the natal female range for at least 12 months in the belief that time period should be sufficient to eliminate the benefits of prior higher levels of testosterone exposure. However, courts have repealed these guidelines, citing a lack of supporting evidence. 

Our Study

We studied the longitudinal influence of hormone therapy on athletic performance and body composition among transgender adults on active duty in the US Air Force. For our study, we measured changes in scores from fitness assessments, performed by active duty transgender servicemembers, which occurred between 1-year before starting medical transition and 2 ½ years after. The semiannual standardized fitness assessment included: measurement of height, weight, and waist circumference; maximum number of sit-ups and push-ups in 1 minute; and a timed mile and a half run. We also compared the performance of the transgender servicemembers to the average performance of all Air Force members under the age of 30 from 2004 to 2014.

Our Findings

We had complete fitness and medical data on 46 transwomen and 29 transmen. The average age at gender transition was 26.2 with a standard deviation of 5.5 years.

Transgender Athletes Research Article

For transmen, there was no significant change in body composition (as measured by height, weight, and waist circumference) over time. They were able to perform the same number of sit-ups as cismen prior to hormone therapy and improved with therapy. Push-ups and run times reached that of cismen by the 1-year point. 

For transwomen undergoing hormone therapy, there was an increase in weight over time but no change in waist circumference.  Push-ups and sit-ups declined to the level of ciswomen by the 2-year mark, but transwomen still retained an 12% advantage in run times. 

What does this mean?

In elite level or collegiate athletic competition, where a 1-2% advantage in speed or strength is often the difference between victory and defeat, governing bodies need to re-examine guidelines for inclusion of transgender and other women with elevated testosterone levels and determine what evidence-based changes are required to ensure a level playing field. 

In youth and recreational sports there is such a broad range of baseline ability, training, and development that 12 months of testosterone suppression is probably adequate to erase any meaningful competitive advantage due to prior testosterone exposure. At that point, we think the benefits of inclusion of all athletes should take priority of any remaining concerns over fairness. Especially since any remaining advantage will continue to shrink with continued suppression of testosterone. When establishing guidelines for youth and recreational sports, the question has to be: “What is the best thing for all our athletes?”



Dale Ahrendt M.D. – Pediatrics, San Antonio Military Medical Center, Fort Sam Houston, Texas, USA

Timothy Roberts MD, MPH – Pediatrics, Children’s Mercy Division of Adolescent Medicine, Kansas City, Missouri, USA

Joshua Smalley DO – Pediatrics, San Antonio Military Medical Center, Fort Sam Houston, Texas, USA


No competing interests



Roberts TA, Smalley J, Ahrendt D. Effect of gender affirming hormones on athletic performance in transwomen and transmen: implications for sporting organisations and legislators. British Journal of Sports Medicine Published Online First: 07 December 2020. doi: 10.1136/bjsports-2020-102329