Transgender sportswomen ‘at a disadvantage’ study claims

Swimming is among the sports that has moved to prevent transwomen from competing in female categories – Getty Images/James Sutton

Transgender female athletes are at a physical disadvantage compared to cisgender women in several key metrics, research funded by the International Olympic Committee (IOC) has found.

The landmark study reported that physically active transgender women performed worse in certain cardiovascular tests and had less lower-body strength than their cisgender females. Researchers at the University of Brighton also found that, contrary to previous claims, transgender women’s bone density was equivalent to cisgender females. Bone density is linked to muscle strength.

The research paper, which has been published in the British Journal of Sports Medicine, could have a significant effect on the debate around gender-inclusion in sport.

It is the first research relating to the issue that the IOC has funded and is the first scientific study of “athletes” who have undergone gender-affirming hormone therapy.

The authors, who included a member of the IOC’s medical and scientific commission, said their results showed that sporting federations should caution against banning transgender women from the female category without further research into their individual sports.

“While longitudinal transitioning studies of transgender athletes are urgently needed, these results should caution against precautionary bans and sport eligibility exclusions that are not based on sport-specific (or sport-relevant) research,” the paper said in its conclusions.

They added that the research could be used to inform policy-making at a time when several sports have excluded transgender women from the female category – including athletics, swimming and cycling – but could not on its own provide the basis for decisions.

How the study worked

Designed to examine the effect of transitioning from male to female and vice versa among physically active subjects, the study collected data from 69 volunteers, who had responded to social-media adverts seeking participants in the research.

The cohort comprised 19 transgender women, 20 cisgender women, 19 cisgender men and 11 transgender men. To qualify for the study, they had to be taking part in competitive sport or physical training at least three times a week. The transgender volunteers needed to have undergone hormonal therapy for at least a year. None of the subjects were competing in national or international sport.

They were assessed across three categories: cardio-respiratory fitness, strength and body composition.

Researchers found that transgender women performed worse than cisgender women in the countermovement jump that tests lower-body strength. It involves jumping vertically with hands on the hips. Transgender women’s average jump was 36.4cm with a standard deviation (SD) of 7.9cm. Cisgender women’s average was 40.7cm with a SD of 5.8cm.

Cisgender women also performed worse in an important test of lung function called the FEV1/FVC ratio, which compares subjects’ Forced Expiratory Volume with their Forced Vital Capacity.

The former is the maximum amount of air that is expelled during the first second following a deep inhalation. The latter represents the volume of air that can be exhaled following a deep inhalation and is a measurement of lung size.

Transgender women had a lower FEV1, leading to a lower FEV1/FVC ratio of 0.83, with a SD of 0.07, compared to 0.88 and a SD of 0.04 for cisgender women. This, the study says, represents a significant difference and could adversely affect transgender women’s athletic performance.

There was no meaningful difference between the two groups’ haemoglobin profiles and bone density – both of which are related to athletic performance – even though, the researchers noted, previous studies of sedentary subjects found that transgender women performed better in both.

The results further showed that transgender women had a significantly higher percentage of fat mass, lower fat-free mass and weaker handgrip strength than cisgender men.

Professor Yannis Pitsiladis, who led the research, said that such discrepancies should prevent anyone viewing the two groups as synonymous when addressing the issue of gender inclusion. Pitsiladis sits on the IOC’s medical and scientific commission.

“The profound message from this research needing to be heard loud and clear by all international federations in their assessment of the limited literature when determining their transgender policy is the requirement to treat trans women as very different to cis men,” he told Telegraph Sport.

Transgender women do have height and weight advantages

Feminising hormonal therapy generally involves taking synthetic oestrogen – the hormone promotes fat accumulation – and, in many cases, antiandrogens to reduce testosterone production.

The purpose of the study was to assess how the effects of such medication could influence athletic performance.

Transgender women were found to have advantages in other respects, including, inevitably, height and weight, as well as lower-body power and handgrip strength.

The study also used a statistic called the gynoid-to-android ratio to assess how fat is distributed around the body. Gynoid relates to the typical female body shape in which tissue accumulates around the hips and thighs. Android refers to the male body’s inclination to build up fat around the midriff.

Transgender women actually had a higher average ratio – 0.97 compared to 0.78 – which, in theory, is less advantageous for certain sports, including weightlifting, for example.

That transgender women performed worse in several metrics shows, the authors argued, that further research is needed before sporting federations decide whether to ban them from the female category.

World Athletics, World Aquatics and cycling’s governing body, the UCI, are among those global sporting bodies that have banned transgender women from female sport in the past 18 months, with the swimming authority going as far as to create a third category for transgender athletes.

The IOC framework on gender inclusion effectively leaves it up to individual sports to decide on the best approach to balance the demands of inclusion and fairness for women’s sport.

The Brighton researchers, however, who took one set of measurements from each volunteer, said that longer-term research was now required, ideally with subjects drawn from a wider population than just the UK.

They also noted the limitations of research in which each category of volunteer had a sample size of less than 30. This was partly because of the difficulty in finding transgender subjects.

Pitsiladis, who is based at Hong Kong Baptist University, led a team of six academics who worked on the research. They also included Blair Hamilton, a transgender woman and sports scientist who drafted the final paper. Hamilton is an athlete herself, having been picked as goalkeeper for the English Universities’ women’s football team. Three men and a woman made up the team.

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