Changes start within three months and a small study shows that at three years they are continuing. Exactly how long these changes continue is unknown.
Notably, muscle mass doesn’t correlate precisely with strength or power, and depends upon height and other factors. No long-term research with adequate comparison groups (adjusted for height) has examined the impact of hormone therapy on strength, fitness or endurance. It is possible that a larger stature may be an advantage for some sports. It is also possible that someone with larger stature, but smaller muscle mass, might be at a disadvantage. I use the analogy of a four-wheel-drive with a hatchback engine. It might look powerful, but performance won’t match appearance.
Media reports about Lia Thomas “dominating” US college swimming appear to be subject to implicit bias. What isn’t reported is that she has abided by all guidelines for testosterone-lowering over three years, and her recent 500-yard-freestyle winning time of 4:33.24 was slower than the National Collegiate Athletics Association record of 4:24.06 and the 4:31.34 achieved by the defending champion Brooke Forde, who has said she does not have a problem racing against Thomas. As a comparison, the men’s final times ranged from 4:06.61 for first place to 4:14.30 for eighth.
Much remains unknown scientifically. Should there be different testosterone level thresholds and treatment duration times that would ensure a level playing field for different sports? At present, no data suggests safety in women’s sport is compromised by including trans women. Various codes already have in place rules to deal with safety (i.e. weight categories or rough play guidelines).
As a doctor, I have found motivating people to exercise an enormous challenge. Trans people aren’t exercising or playing sport. A Human Rights Campaign Foundation study in 2017 found that 68 per cent of high school students participated in sport, 28 per cent of lesbian, gay and bisexual students but only 12 per cent of trans girls, often because of fear of discrimination.
Yet trans people need exercise for its physical and mental health benefits. Trans women have higher risk of heart attacks than the general population, 73 per cent have depression and an alarming 43 per cent have attempted suicide. Exercise has profound benefits on physical and mental health, community and belonging.
We need to break down barriers to encourage trans people to exercise and participate.
So, is the recent debate a storm in a teacup? The Sex Discrimination Act already allows for discrimination in sport where relevant. No sporting organisations have called for a revision. Sport Australia, with the Australian Human Rights Commission, has existing guidelines for the inclusion of trans people in sport. Of the last 71,000 Olympians, only two were trans women. One came last, the other 37 out of 42.
Further research is coming. My research group at the University of Melbourne, in collaboration with the Institute for Health and Sport at Victoria University, have started the GAME research study examining how feminising hormones impact fitness, endurance, physique and gene changes in muscle over time in comparison groups. With funding and volunteer participants (both trans and not trans), we can provide better evidence-based guidance for sports policy.
In the meantime, the unrelenting debate uses an already marginalised and traumatised trans community with substantial mental health vulnerabilities as political footballs. LGBTQ mental health services are telling me they’re experiencing the highest demand in nearly 20 years. Our leaders and legislators must avoid fear-driven policies and make balanced evidence-based decisions for the benefit of all in the communities that they serve.
Associate Professor Ada Cheung is an endocrinologist at Austin Health and leads the Trans Health Research Group at the University of Melbourne. Support is available: Lifeline 13 11 14; QLife 1800184527
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