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How gender affirming hormones influence performance in transwomen and transmen?

Summary of a study following physical performance changes in transwomen and transman from pre-transition to 2.5 years after.

Who

29 self-identified transmen and 46 transwomen military personnel (US Air Force) who were undergoing gender affirming therapy aged 26.2 ± 5.5 years (USA).

transwomana person who transitioned from male to female.

transmana person who transitioned from female to male.

Design

Retrospective review of medical records including fitness test scores in the first 30 months after strating gender affirming therapy (with testosterone or oestrogen).

Outcome measures/tests

  • height, weight, waist circumference
  • number of push ups in 1 minute
  • number of sit ups in 1 minute
  • timed 1.5 mile run

Main results

How gender affirming hormones influence performance in transwomen and transmen - Infographic

  • The study followed participants for 394 ± 288 days after starting testosterone or oestrogen.

  • Pre-treatment fitness assessment was performed on average 144 ± 101 days before starting testosterone or oestrogen therapy.

  • Transwomen:

    • Most transwomen had oral oestradiol (67.4%) prescribed, with first therapeutic hormone level recorded (median) at 234 days. Most used spironolactone (80.4%) for testosterone blockade with fist documented suppression (median) at 200 days.
    • Transwomen were heavier than average women and lighter than average man in the Air Force pre-transition. These differences stayed for at least 2.5 years after starting the transition.
    • Pre-transition transwomen performed fewer push-ups in 1 minute than men (this difference increased with time) but more push-ups than women in the Air Force (this difference disappeared after 2 years of hormonal therapy).
    • Pre-transition transwomen could do more sit-ups in 1 minute than women but the same as Air Force men. After 2 years of therapy, transwomen performed the same number of sit-ups as women, but less than Air Force men.
    • Run times for transwomen were similar to men pre-transition and better than women. After starting the therapy the run times worsened but stayed better than for women for at least 2.5 years.
  • Transmen:

    • Most transmen had testoserone cypionate (89.7%) prescribed with 98.5 days (median) to record first therapeutic levels.
    • Transmen were lighter than average men and heavier than the average women. These differences stayed for at least 2.5 years after starting the transition.
    • Pre-transformation transmen performed more push-ups and sit-ups in 1 minute than Air Force women. The difference in sit-ups and push-ups between transmen and women grew through the transition.
    • Compared to Air Force men, transmen could do less push-ups before starting the transition, but cought up within 1 year. The number of sit-ups was similar between transmen and men pre-transition, and after 1 year into transition, transmen could do more sit-ups than men.
    • Pre-transition transmen were similar in 1.5 mile run to women but slower than men. After 1 year into transtion, transmen were faster than women and similar to men.

Take home message

For a clinician & coach
For transwomen, first therapeutic hormone level was recorded (median) at 234 days, with fist documented testosterone suppression (median) at 200 days. For transmen, it took 98.5 days (median) to record first therapeutic levels of testosterone. After 2.5 years of gender affirming hormonal therapy, transwomen performed better than average Air Force woman in 1.5-mile run, and transmen performed better than average Air Force man in push-ups and sit-ups.
For a parent
After 2.5 years after transitioning, transwomen performed better than average Air Force woman in 1.5-mile run, and transmen performed better than average Air Force man in push-ups and sit-ups.
For an athlete
After 2.5 years after transitioning, transwomen performed better than average Air Force woman in 1.5-mile run, and transmen performed better than average Air Force man in push-ups and sit-ups.

Original article

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. 2021 Jun 1;55(11):577-83.

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