Gender and Sports: Can Science Enable Fair Competition?

The allegations against Algerian boxer Imane Khelif at the Paris Olympics raised the questions of intersexuality and its implications in competitive sports. Univadis Italy has decided to delve into the topic to assist doctors who suspect a similar condition in their patient. No certain clinical data about Khelif have been made public, so this article does not concern the boxer but rather takes inspiration from the media controversy.
What Is Intersexuality?
Intersexuality encompasses a spectrum of variations in sexual development that lead to the simultaneous presence of typical male and female characteristics. As reiterated by the United Nations Office of the High Commissioner for Human Rights, the medical definition does not affect the patient’s self-identification of gender or sexual orientation.
“The percentage of people who fall within the intersexuality spectrum is less than 0.5 per thousand of the general population, but there are no precise statistics, given the difficulty of definition,” said Roberto Lala, MD, pediatric endocrinologist and president of the Federation of Rare Childhood Diseases.
Indeed, there is not only a strict definition of intersexuality that involves a significant presence of these mixed physical characteristics in a way that conditions the self-image of the subject but also a broad definition, said Lala. “For example, clitoral hypertrophy in a female otherwise conforming to the female gender, which does not raise doubts about identity,” he said.
Chromosomes, Genes, and Hormones
A patient’s sexual characteristics are determined by the complex interaction of chromosomal, genetic, and hormonal factors. “The human body is, so to speak, programmed to take on female appearances in development and shifts toward male ones only if exposed to testosterone and other factors. For this to happen, testosterone must be produced during embryonic development, and it must function properly,” said Paolo Moghetti, full professor of endocrinology at the University of Verona, Verona, Italy.
The protein encoded by SRY, which is located on the Y chromosome, determines the development of the testicles from undifferentiated tissue of the embryonic gonads. The testicles of the embryo then produce testosterone. The absence of the Y chromosome is a common characteristic of most female individuals. However, there are individuals with a female phenotype who have X and Y chromosomes but lack SRY or have a variant of it that is not entirely functional.
Numerous other chromosomal or genetic variations can lead to alterations in sexual differentiation. “In phenotypically male adult subjects (with a chromosomal makeup of 46XY) with complete androgen insensitivity (so-called Morris syndrome), testosterone levels in the blood are elevated, above normal even for a male, but the hormone is totally ineffective, and the phenotype is totally female at birth, with completely female development of secondary sexual characteristics at puberty,” said Moghetti.
This means that affected individuals have well-developed breasts and a complete lack or extremely reduced presence of hair, including underarm and pubic hair. Menstruation is also completely absent because there is no uterus, and there are testes, not visible because they are considered in the abdomen.
“There are syndromes that are currently considered congenital but not genetic, of which a genetic origin will probably be identified in the future,” said Lala.
Some variations in sexual development can be diagnosed prenatally, such as an alteration of the number of sex chromosomes or a discordance between the morphologic characteristics highlighted by ultrasound and the genotype detected by amniocentesis. Some variations are evident at birth because of atypical anatomical characteristics. Others are diagnosed during puberty or later in adulthood, in the presence of infertility. The Italian National Institute of Health details these variations on its website, describing the characteristics that determine diagnosis and treatment.
Pathologies or Variations?
Some anomalies in sexual development negatively affect the patient’s physical health. One example is congenital adrenal hyperplasia. “It results from an inherited defect of the adrenal glands, which reduces cortisol production while increasing testosterone production,” said Lala. “In addition to the appearance of male characteristics in females, in more severe forms, it carries the risk of collapse and shock and requires pharmacological treatment.” It is undoubtedly a pathology.
Other variations in sexual characteristics do not affect the patient’s physical health negatively. They may, however, have a psychologic effect, sometimes a significant one, because of the lack of social acceptance of a person who cannot be classified within the binary classification of sexes.
“Conditions in which mixed male and female aspects are clearly evident have been and are still pathologized by the family, the treating physician, and society,” said Lala. “In the late 1970s, when a child was born with intersexual anatomical characteristics, it was common practice to surgically intervene, making them female, because it was technically easier.”
Over the years, patients who, as they grew up, were dissatisfied with the solution adopted at birth began to make their voices heard, Lala added. Scientific societies and international organizations have spoken out against subjecting intersexual newborns to surgical interventions that are not medically necessary. “Nowadays, decisions are made on a case-by-case basis, taking into account the families’ wishes. Interventions are justified with medical reasons, which are often very nuanced,” Lala concluded.
Implications for Sports
Traditionally, athletes participating in competitions in certain sports have been divided into male and female categories to ensure a certain equity and uniformity in performance. Over the years, the emergence of new information about sexual development has made it necessary to update the criteria used in this division.
The main factor responsible for the performance diversity between males and females is the action of testosterone on the male and female organism. “Testosterone has important effects on muscle mass and enhances training results,” said Moghetti. “As a demonstration of this fact, before puberty, the best performances in athletics or swimming by males and females are similar, then males gain a significant advantage of around 10%-20%.”
A few years ago, the World Athletics Federation conducted widespread screening of athletes participating in its world championships. “It identified a small group of individuals with potentially abnormal testosterone levels for the female sex,” said Moghetti. “Some were found to be doping, others had genetic defects, and for some, an interpretation was not even possible.”
Some of the individuals had a male genotype but a defect in 5-alpha-reductase, an enzyme essential for the formation of male genitals and hair growth. An athlete with these characteristics, assigned female sex at birth, has a male level of testosterone that stimulates the accumulation of muscle mass, Moghetti explained. Therefore, the individual has a considerable advantage in performances influenced by this hormone.
“In the end, the Federation decided to set limits on the testosterone levels of athletes participating in certain types of races, especially those in middle distance, that appeared to be more sensitive to differences in hormone levels,” said Moghetti. “The limitation does not apply to athletes with Morris syndrome, ie, with a male genotype and complete resistance to testosterone, for whom the high level of this hormone does not provide any advantage.” Given the complexity of the problem, he hopes for a case-by-case policy that considers the needs of patients with genetic alterations and those of athletes who have to compete with them.
Not the First Time
A recent incident underscored the difficulty of regulating such complex issues. The World Athletics Federation excluded South African middle-distance runner Caster Semenya from competitions years ago because of excessively high testosterone levels.
“The Federation’s regulations recommend that athletes in these cases reduce hormone levels to values below the threshold of 5 nmol/L of blood for a period of at least 6 months before the race by using hormonal contraceptives. The use of such drugs does not pose a health risk, as they are substances normally taken by women for contraception purposes,” said Amelia Filippelli, a pharmacologist at the University of Salerno in Italy. The South African middle-distance runner refused the drug and appealed to the Court of Arbitration for Sport and later to the Swiss Federal Court. Both rejected her appeal. Finally, Semenya appealed to the European Court of Human Rights, which in 2023 recognized a violation of her rights but does not have the authority to order a change in the Federation’s regulations.
Beyond the ideologic positions of nonexperts, therefore, the issue is still the subject of debate in the scientific community, which is evaluating not only its medical aspects but also its ethical implications.
This story was translated from Univadis Italy, which is part of the Medscape professional network, using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.
 
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