Testosterone: Sometimes the genes are an unusual fit

Pick any athletic discipline and you’ll find men perform roughly a tenth better than women. That is why there must be a way to sort the men from the women, the likes of the International Association of Athletics Federations (IAAF) argues, just as boxers are divided into weight classes.

But as much as athletics craves a sharp delineation between men and women, science is unable to deliver. If anything, science continues to make the problem more tricky.

Sporting bodies first sought to distinguish men from women by way of genital exams, naturally administered only to women.

That approach was halted, not because of its fundamentally invasive and offensive nature but because science pointed out that the state of external genitalia makes little difference to what makes men faster and stronger. Though never cited as such, the relative ease of surgically altering external genitalia may also have weighed on the minds of sports administrators.

In the 1960s the sporting world turned to the far more palatable chromosome testing for gender determination, using a cheek-swab test. Even as it did so, science was there to point out that the idea was fundamentally daft. Most men do have XY chromosomes and most women have XX chromosomes, but that is only on average.

The World Health Organisation estimates that several people in every thousand have either just an X or just a Y sex chromosome, and some have three or more, making them XXY, or XYY or some other variant. That is before confounding factors such as androgen insensitivity syndrome, which can see a XY person — who would usually develop as a male — develop as a female instead, or the further confusion that androgen insensitivity has three recognised categories of effect. People outside the XY/XX divide are not typical, but then neither are professional athletes.

In Olympic sport chromosome testing was, on paper, replaced with the consideration of a range of factors. As a November 2015 consensus position by the International Olympic Committee shows, however, it all came down to testoster- one, primarily a male hormone. By that consensus, anyone who transitions from female to male can compete with no restrictions.

Those who transition from male to female, though, are required to keep their levels of testosterone below a specified level, 10 nanomoles per litre in serum, with mandatory testing and a 12-month ban for drifting into “male” levels of testosterone. The same limit on testosterone was in place for women athletes in what the IAAF dubbed regulations on hyperandrogenism, adopting a term for a medical condition.

But in a complex ruling running to more than 160 pages, the Court of Arbitration for Sport in July 2015 suspended those regulations for lack of evidence in a matter brought by Indian athlete Dutee Chand.

Although evidence indicates that higher natural testosterone “may increase athletic performance”, the court said, it was “not satisfied that the degree of that advantage is more significant than the advantage derived from the numerous other variables which the parties acknowledge also affect female athletic performance: for example, nutrition, access to specialist training facilities and coaching, and other genetic and biological variations.

“Further evidence as to the quantitative relationship between androgen levels in hyperandrogenic females and increased athletic performance is therefore required,” the court said. —