The greatest divide in sport today

You're too big, too strong and too fast to play. That is what Hannah Mouncey, an Australian AFL player was effectively told when she applied to play in the Women's Australian Football League last week.

It's not the simple discrimination you might think, though. Rather, it's the latest manifestation of one of sport's most complex problems, that of the male-female sporting separation when women have high testosterone levels as a result of being biologically/genetically male.

Hannah Mouncey, you see, used to be Callum Mouncey, a male professional handball athlete in 2016, who is now a transgender female and seeking a new career in the AFL, as a woman.

In rejecting her application, the AFL invoked the Victorian Equal Opportunity Act, which states that athletes can be discriminated against based on their sex or gender "if strength, stamina or physique is relevant".

The decision has attracted criticism. It was called "a slap in the face for every AFLW player", because it apparently tells Mouncey's prospective opponents they're not big enough or strong enough to compete against her.

At 100kg and 1.9m tall, Mouncey the handball player would indeed make an imposing opponent.

The problem is that some of Mouncey's female opponents are similar to her in height, if not mass, and so the distinction between "too big" and "similar enough" is not clear.

If Mouncey were 85kg and 1.9m, would that be small enough to be fair?

Nobody knows, which is a source of some of the criticism. That said, the AFL did not look only at her size and height. It also used data from performance tests, including vertical jump height (used to measure an athlete's power), a 2km running time-trial, and a set of weightlifting exercises (for strength).

Based on these measurements, the AFL decided, for 2018 only, to reject Mouncey. She may reapply for 2019, and presumably if those physical and performance measurements have "retreated" towards what is typical in her prospective opponents, she could be cleared to play. Here again, the question is: "How similar does she need to be?"

The International Olympic Committee, for its part, doesn't weigh in on this issue of advantage. It does have "transgender guidelines" that allow transgender females (male-to-female) to compete as females provided their testosterone levels have remained below a cut-off limit for 12 months.

The IOC doesn't mention performance, because it's too sport-specific, and too difficult to pin down without seeming arbitrary and discriminatory - being "too good" isn't grounds for exclusion.

The IOC guidelines are "not mandatory", and it's up to individual federations to use additional or different criteria when making decisions.

The AFL has decided that size, stature, power and speed, all of which are at least partly influenced by the male hormone testosterone, are enough to ban Mouncey, at least for now.

Theoretically, I have no problem with this. In fact, I agree. The concern is whether the data supports the concept, in that differences in these attributes must be clear enough to ensure complete separation.

Men and women are kept separate in sport because testosterone and other male hormones cause physiological changes that give men a large performance advantage. Without a separate category, women would effectively disappear from most elite sports, and this is a biological reality.

There is considerable sympathy for Mouncey - she is exercising her right to identify however she chooses. However, I'd argue that this does not equate with the right to participate in elite sport. It's like a 90kg boxer insisting they have a right to fight as a 61kg lightweight - the rules prevent it, and that's sport.

This is a problem that will only grow, and without a solution that keeps everyone happy, more controversy can be expected.