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Two new scientific reviews agree that transwomen athletes retain male advantage

The debate around inclusion of transgender athletes – and in particular whether biological males who identify as women should play in female sporting competitions and teams – is a fraught one. On one hand are those who advocate for fairness, and protection for the female category in sport; on the other are those who advocate for inclusion.

What does the evidence show? Two reviews have recently been published in peer-reviewed, high-quality, high-impact sports-medicine journals. They use an almost completely overlapping dataset of clinical data. Notably, the lead authors of each review come from different perspectives; with Emma Hilton (one of the co-founders of Sex Matters) prioritising fairness and Joanna Harper prioritising inclusion.

Indeed, Harper, a transwoman and middle-distance runner, has advised many sporting federations, and an earlier study (Harper, 2015) of post-transition performance in transwomen runners was instrumental in persuading the International Olympic Committee to reduce the stringency of their inclusion criteria, making it easier for transwomen to qualify for female categories. 

However, the two studies arrive at the same conclusion: male athletes suppressing testosterone in order to transition lose little in the way of muscle mass and strength, with advantage over females being retained for at least three years.   

The two independent reviews look at musculoskeletal changes in male athletes suppressing testosterone, using data collected during the course of their clinical care. 

Hilton and Lundberg, 2021 conclude:

Superior anthropometric, muscle mass and strength parameters achieved by males at puberty, and underpinning a considerable portion of the male performance advantage over females, are not removed by the current regimen of testosterone suppression permitting participation of transgender women in female sports categories. Rather, it appears that the male performance advantage remains substantial.

Hilton and Lundberg, 2021

Harper et al., 2021 find:

Hormone therapy decreases strength, LBM [lean body mass] and muscle area, yet values remain above that observed in cisgender women, even after 36 months. These findings suggest that strength may be well preserved in transwomen during the first 3 years of hormone therapy.

Harper et al., 2021

That scientists coming to the issue from two different angles reach the same conclusions about a given dataset should foster confidence in the scientific process and the conclusions reached by both groups.

There is emerging recognition from all sides that the muscle and skeletal advantages provided to males by virtue of their biological sex are not undone by transition, and this must be considered by sports federations when designing policies for female sport.