Transgender and Intersex Athletes in Sport: Policy and Science

Navigating gender affirmation in sport requires balancing two fundamental principles: competitive fairness and the human right to participate in public life. In recent years, international governing bodies, elite athletic leagues, and recreational sports associations have radically revised their policies regarding transgender and intersex athletes. These changes have created a complex patchwork of regulations that varies significantly depending on the discipline, country, and level of competition.

For transgender women, non-binary individuals, and intersex athletes with variations in sex characteristics, the landscape of sports participation is increasingly restrictive. Understanding the medical realities, scientific debates, and regulatory frameworks behind these policies is essential for athletes, advocates, and sports administrators alike.

The Evolution of Inclusion Policies in Elite Sport

For decades, international sports federations evaluated eligibility based on biological markers that were presumed to provide clear binary distinctions. In the late twentieth century, chromosome testing and physical examinations were standard practice. These methods proved scientifically unreliable and deeply invasive, frequently harming intersex athletes who were unaware of their hyperandrogenism or chromosomal variations.

In 2003, the International Olympic Committee published the Stockholm Consensus, which established the first formal pathway for transgender athletes to compete in their affirmed gender. This framework required individuals to undergo gender affirmation surgery, possess legal identity documents matching their gender identity, and complete at least two years of post-surgical hormone therapy.

By 2015, the guidelines shifted away from surgical requirements. The updated framework permitted transgender women to compete in the female category if their total serum testosterone levels remained below 10 nanomoles per litre for at least 12 months prior to competition. This standard aimed to align sports regulations with modern endocrinological evidence while removing unnecessary surgical mandates.

The Shift Toward Testosterone Limits and Category Restriction

The regulatory environment altered substantially following the 2021 release of the framework on fairness, inclusion, and non-discrimination by the International Olympic Committee. Rather than setting a single overarching rule for all sports, the framework shifted responsibility to individual sports governing bodies. Each international federation was instructed to draft its own eligibility criteria based on sports-specific research.

This decentralized approach led several major federations to enact much stricter restrictions. In 2022 and 2023, governing bodies for swimming, athletics, and cycling introduced policies that effectively excluded transgender women from the elite female category if they had undergone any part of male puberty.

Medical guidelines show that physiological traits vary widely across all human bodies, making single biological metrics an imprecise measure of athletic advantage.

These updated policies mark a shift from managing hormone levels during active competition to focusing on early developmental exposure to endogenously produced testosterone. Consequently, many elite transgender and intersex athletes find themselves ineligible for the categories corresponding to their gender identity, regardless of their current hormone levels or athletic performance.

The Physiology of Athletic Performance and Hormone Suppression

The scientific debate surrounding transgender inclusion centres on how puberty influences physiological development and to what extent gender-affirming hormone therapy alters these traits. Endogenous testosterone during male puberty promotes increased bone density, larger lung capacity, higher hemoglobin concentration, and greater muscle mass.

When transgender women undergo gender-affirming hormone therapy, testosterone is suppressed to typical female levels, and estrogen is introduced. Longitudinal studies demonstrate that this therapy reduces muscle mass, strength, and red blood cell count within 12 to 36 months, bringing hemoglobin levels into the standard female range rapidly.

However, scientific research also indicates that certain structural features, such as bone geometry and lung size, do not reverse after puberty. Controversy remains regarding how much retained muscle memory or skeletal structure translates to a meaningful competitive advantage in specific sports. Medical experts emphasize that physiological variations exist across all human bodies, and elite athletes in every category frequently possess distinct genetic advantages over their peers.

Intersex Athletes and the Impact of Endogenous Testosterone Rules

Intersex athletes face distinct challenges under current regulations, particularly those who have natural variations in sex characteristics resulting in higher endogenous testosterone levels, known as hyperandrogenism. World Athletics and other federations have implemented specific regulations for athletes with differences of sexual development who compete in female events.

These regulations require intersex athletes with specific genetic profiles to suppress their natural testosterone levels below strict thresholds, often 2.5 nanomoles per litre, for a continuous period before becoming eligible to compete. If an athlete chooses not to undergo medical interventions to lower their testosterone, they are excluded from the female category in restricted events.

Human rights organizations and medical ethics bodies have criticized these mandatory suppression policies. Critics argue that forcing healthy athletes to undergo medically unnecessary hormonal interventions as a condition of competing infringes upon bodily autonomy and physical integrity. Furthermore, these regulations disproportionately affect women from the Global South, who have historically been subjected to public scrutiny, non-consensual medical testing, and forced exclusion from elite sport.

Non-Binary Participation and Category Design

While much of the public debate focuses on the binary female category, non-binary athletes present distinct considerations for traditional sports structures. Sports have historically operated on a rigid male-female binary, leaving non-binary individuals without a clear, affirming category in which to compete.

To foster greater inclusion, several sporting organizations are experimenting with alternative category designs:

• Open categories, where any athlete may compete regardless of gender identity, sex assigned at birth, or hormone levels, alongside a protected female category.
• Universal scoring systems, which adjust handicap systems or scoring metrics based on individual physiology rather than binary gender classifications.
• Expanded non-binary divisions, which create dedicated competition fields for non-binary and gender-diverse participants, particularly in endurance sports such as marathons.

While open categories offer a practical solution for participation, advocacy groups note that reclassifying the male category as an open category can sometimes cause non-binary or transgender female athletes to feel relegated to a secondary status rather than fully included.

Grassroots and Recreational Sport versus Elite Competition

A critical distinction in this debate exists between elite international competition and community-level recreational sport. At the elite level, regulations are driven by financial stakes, international records, and elite selection. At the grassroots level, the primary goals of sport are physical health, social connection, mental well-being, and community cohesion.

Applying elite hormonal and physiological restrictions to youth or community sports creates significant barriers to participation. Research demonstrates that transgender and gender-diverse individuals experience higher rates of social isolation, anxiety, and depression. Exclusion from recreational sports groups removes a key source of physical activity and community support.

Recognizing these differences, many national sporting bodies have established tiered policies. These guidelines permit open self-determination for social, school, and recreational sports, reserving biological testing and hormonal requirements strictly for high-performance and national representation levels.

Protecting Fairness and Human Rights in Future Policy

Developing equitable sports policies requires balancing competitive fairness, human dignity, and evidence-based science. Medical organizations advocate for continued research into transgender and intersex physiology, noting that existing studies often rely on small sample sizes or non-athletic populations.

Future frameworks will likely rely on nuanced, sport-specific evaluations rather than blanket bans or broad generalizations across all athletic disciplines. Ensuring that regulations are developed with input from medical professionals, legal scholars, and affected athletes is essential to creating policies that respect human rights while safeguarding sports integrity.

Supporting Inclusive Healthcare and Equity

Achieving fair treatment in sport is directly connected to broader health equity, self-determination, and access to respectful medical care. For transgender and intersex people, the freedom to participate in public life, including physical culture, relies on societal recognition of their bodily autonomy and health rights.

Jordyn Kao is an intersex and transgender woman living in the Netherlands who writes extensively on trans health, legal recognition, and bodily autonomy. Having navigated the healthcare system across South Africa and Europe, she is currently raising funds for medically necessary gender-affirming surgery. Supporting her campaign helps advance her health journey and contributes to ongoing advocacy for intersex and transgender rights globally.