by 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 physical strength than their transgender counterparts. Researchers at the University of Brighton also found that, contrary to previous claims, the bone density of transgender women was the same as that of transgender women. Bone density is linked to muscle strength.
The research paper, published in the British Journal of Sports Medicine, could have a significant impact on the debate about gender inclusion in sport.
This is the first research on the issue funded by the IOC and the first scientific study of “athletes” who underwent gender-affirming hormone therapy.
The authors, who included a member of the IOC’s medical and scientific commission, said their findings showed sports federations should caution against banning transgender women from the female category without further research into their individual sports.
“While longitudinal transfer studies of transgender athletes are urgently needed, these findings should be weighed against precautionary bans and exclusions of sports eligibility that are not based on sport-specific (or sport-related) research, ” said the paper in its conclusions.
They added that the research could be used to guide policy-making at a time when transgender women are excluded from some women’s sports – including athletics, swimming and cycling – but could not alone 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 responded to social media advertisements seeking research participants.
The cohort included 19 transgender women, 20 cisgender women, 19 cisgender men and 11 transgender men. To qualify for the study, they had to be participating in competitive sport or physical training at least three times a week. The transgender volunteers had to undergo hormone therapy for at least a year. None of the subjects had competed in national or international sport.
They were assessed across three categories: cardiorespiratory 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 hips. The average height of transgender women was 36.4cm with a standard deviation (SD) of 7.9cm. The mean height of cisgender women 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 to their Forced Vital Capacity.
The first is the maximum amount of air expelled in the first second after a deep inhalation. The latter represents the volume of air that can be exhaled after a deep inhalation and is a measure of lung size.
Transgender women had lower FEV1, resulting in a lower FEV1/FVC ratio of 0.83, with an SD of 0.07, compared to 0.88 and an SD of 0.04 for cisgender women. This, the study says, represents a significant difference and could have a negative impact on transgender women’s athletic performance.
There was no significant difference between the two groups’ hemoglobin profiles and bone density – both of which are linked to athletic performance – although the researchers noted that previous studies of sedentary subjects found that transgender women did better in both group.
The results also showed that transgender women had a significantly higher percentage of fat mass, lower fat-free mass and weaker hand grip strength than transgender men.
Professor Yannis Pitsiladis, who led the research, said that such discrepancies should prevent anyone from 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 that all international federations need to hear clearly when assessing the limited literature and determining their transgender policy is the requirement to treat transgender women as very different from cis men, ” he told Telegraph Sport.
Transgender women do there are advantages of height and weight
Female hormone therapy generally involves taking synthetic estrogen – the hormone that promotes fat accumulation – and, in many cases, antiandrogens to reduce testosterone production.
The purpose of the study was to assess how such medications might affect athletic performance.
Transgender women were found to have advantages in other ways, including, of course, height and weight, as well as lower body power and hand grip strength.
The study also used a statistic called the gynoid-to-Android ratio to assess how fat is distributed throughout the body. Android is associated with the typical female body shape where tissue gathers around the hips and thighs. Gynoid refers to the tendency of the male body to build fat around the middle.
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.
The authors point out that transgender women fared worse in some metrics, further research is needed before sports federations decide whether to ban them from the women’s category.
Among the world sports bodies that have banned transgender women from women’s sport in the last 18 months are the governing body World Athletics, World Aquatics and cycling, the UCI, and the swimming authority going as far as create a third category for transgender athletes.
The IOC framework on gender inclusion effectively leaves it up to the individual sports to decide the best approach to balancing the demands of inclusion and fairness for women’s sport.
However, the Brighton researchers, who took one set of measurements from each volunteer, said longer-term research was now needed, ideally with subjects drawn from a wider population than just the UK.
They also noted the limitations of the research where each category of volunteer had a sample size of less than 30. This was partly due to the difficulty of finding transgender subjects.
Pitsiladis, based at Hong Kong Baptist University, led a team of six academics who worked on the research. Also among them was Blair Hamilton, a transgender woman and sports scientist who drafted the final paper. Hamilton is an athlete herself, having been selected as a goalkeeper for the English Universities women’s football team. Three men and a woman made up the team.
