Transgender Women Athletes and Elite Sport: A Scientific Review

In 2022, the Canadian Centre for Ethics in Sport (now called Sport Integrity Canada) published "Transgender Women Athletes and Elite Sport: A Scientific Review," an in-depth review of scientific literature on transgender athlete participation in competitive sport.

Today, it was discovered that this report has been removed or blocked from their site; all materials are under the "Resources" section of this site.

The CCES report reviewed published literature from 2011 to 2021 to determine what the studies actually said - and what they did not. Notably, the report found:

• Biomedical factors related to puberty (i.e., lung size, bone density, hip-to-knee joint angle [q-angle]) do not predict athletic performance.

• Social factors like nutrition, training, and access to equipment greatly impact an athlete’s performance, yet are consistently overlooked in policy-making.

• Biomedical and social scientific information should both be used in policy-making. However, biomedical research is often overvalued to the detriment of athlete well-being.

Current medical research tells us:

• Testosterone levels do not predict athletic performance or overall athleticism.

• Recent studies have found that lung capacity, bone density, and hip-to-knee joint angle (q-angle) do not correlate with competitive advantage.

• All people have estrogen and testosterone. The distribution of testosterone levels between elite cisgender men and elite cisgender women athletes overlaps.

• Only three studies have used trans athletes as subjects. They indicate that any potential performance advantages are negated through testosterone suppression after months (and sometimes sooner).

• The majority of sport policies are not evidence-based and have participation requirements that are arbitrary and/or not clearly linked to performance.

The following flaws were found in the existing research:

• Most studies used to inform sport policies about elite trans women use cisgender men or non-athlete trans women as their subjects rather than trans women elite athletes.

• The literature largely ignores sports where cisgender women have advantages over cisgender men (e.g., long-distance swimming).

• A majority of studies examine a single variable (e.g., grip strength, testosterone) and over-emphasize that variable’s impact in predicting athletic ability. In reality, there is not a single variable that can predict athletic ability – a great athlete has any number of social and biological traits that make them successful.

From the Executive Summary:

The report examined peer-reviewed research articles published in the English language between 2011 and 2021. Only peer-reviewed articles or syntheses of academic literature (e.g., meta-analyses) in reputable academic journals were included. Grey literature, or non-academic literature, was included if it provided a summary of empirical data or if it described rules currently in place worldwide to include/exclude trans athletes.

The resulting report is divided into two sections reflecting the primary perspectives by which the question of trans inclusion has been addressed - one that encompasses biomedical studies and a second that encompasses sociocultural studies. While there are questions of inclusion for non-binary and intersex athletes, this report focused on the population of trans women athletes in the context of elite sport.

The research findings in the biomedical area are inconclusive. Studies which make conclusions on pre- and post-hormone replacement therapy (HRT) advantage held by trans women athletes have used either cis men or sedentary trans women as proxies for elite trans women athletes. These group references are not only inappropriate for the context but produce conclusions that cannot be applied to elite trans women athletes. Further, there is little scientific understanding about the attributes or properties of HRT, namely testosterone suppression and estrogen supplementation, on the physiology and athletic ability of trans women athletes. This ignores the potential for estrogen supplementation to reduce Lean Body Mass (LBM), and for testosterone suppression to produce holistic health disadvantages.

For the full report, executive summary, and other documents, visit the Documents page.