The International Association of Athletics Federations (IAAF) has come under intense fire since releasing its new "Eligibility Regulations for the Female Classification".

Key points: Similar regulations were introduced in 2011 but suspended in 2015 after a challenge from an Indian sprinter

Similar regulations were introduced in 2011 but suspended in 2015 after a challenge from an Indian sprinter The IAAF says affected athletes can reduce their testosterone levels by taking hormonal contraceptives

The IAAF says affected athletes can reduce their testosterone levels by taking hormonal contraceptives It also considered the idea of creating a new intersex category

The rules have been called sexist, racist, unethical, and based on bad science, although the governing body is sticking to its guns.

Under the new regulations, from November 1 some female runners with naturally high testosterone levels will be banned from competing over distances from 400 metres to the mile at international meets.

The measures are based on a study it commissioned last year which concluded that "female athletes with high free testosterone (fT) levels have a significant competitive advantage over those with low fT in 400m, 400m hurdles, 800m, hammer throw, and pole vault".

While no specific athletes have been mentioned in the latest criteria, which refers to those who have a "difference of sexual development", many believe South African middle-distance runner Caster Semenya is the clear target.

She unwillingly became the face of athletics' intersex debate after her breakthrough 800m world championships victory in 2009.

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Intersex is defined as people born with sex characteristics that do not fit typical binary notions of male or female bodies.

Intersex Human Rights Australia co-executive director Morgan Carpenter says the IAAF has been very deliberate in the events it has put on the restricted list.

"Superficially it looks so arbitrary that the IAAF has chosen just a tiny range of athletic events to single out for different treatment," he said.

"There's a difference between the events they've singled out now and the events they singled out last year which included, for example, the pole vault and the hammer throw. (They're) singling out Caster Semenya because she's a hardworking, black, powerful South African athlete."

'Blatantly racist'

South Africa's ruling party, the African National Congress, says the measures infringe on athletes' human rights and are "blatantly racist", comparing them to government policies during apartheid.

In a statement it said "the regulations are a painful reminder of our past where an unjust government specifically legislated laws for certain activists in society to stifle their fight against an unjust system.

"The IAAF uses the same tactic to exclude those who have defined the past decade as champions and treasures of their home countries."

The IAAF says the new regulations are about fairness. ( AP Photo: Lee Jin-man )

Katrina Karkazis, a senior visiting fellow in the Global Health Justice Partnership at Yale University, agrees race is a factor in the latest ruling.

"All of the women who have been identified and targeted under the regulation are women from the global south," Dr Karkazis said.

"There are a lot of reasons why that's the case. One of them is that there's not [routine] intervention for women with intersex [characteristics] in the global south in the way that there has been in the global north over the last five decades.

Earlier [reports] have made an argument that the IAAF is bringing good western healthcare to these women, except what they fail to say is that actually intersex adults have been arguing against these particular kinds of interventions for the better part of two decades now."

Mr Carpenter said "as intersex people, we are either forced to submit to medical intervention to become normal, to become more typically female or more typically male, or we are 'othered' as neither female nor male. And these kind of ideas happen simultaneously, and people are being torn apart by this."

'Otherwise females wouldn't win medals'

The IAAF responded on social media insisting that the regulations are neither racist nor sexist.

"Historically the reason we have separate male and female categories is that otherwise females wouldn't win medals. Testosterone is the most important factor in explaining the difference, some females compete with levels similar to males."

The organisation has also emphasised that the rules are not directed at any particular athlete, saying research shows the number of intersex women in elite athletics is 140 times more than the general female population.

It introduced similar regulations in 2011, before they were suspended by the Court of Arbitration for Sport (CAS) after a challenge from Indian sprinter Dutee Chand in 2015.

Indian sprinter Dutee Chand successfully challenged an earlier version of the regulations. ( ABC News: James Bennett )

CAS then gave the IAAF two years to submit further evidence to support its initial ruling, which came in the form of the 2017 study.

The study analysed testosterone levels of a number of male and female athletes competing in the 2011 and 2013 world championships, finding that "in certain events female athletes with high testosterone levels benefit from a 1.8 per cent to 4.5 per cent competitive advantage over female athletes with lower testosterone levels".

'It's research designed to support this regulation'

Dr Karkazis was an expert witness at Chand's CAS appeal, and has raised concerns over the validity of the IAAF's study.

"The research that they're pointing to is their own. In other words, they funded it, they've published it, they've analysed it, so it's not impartial, it's research designed to support this regulation.

"It was published after it was required, not before they decided to institute a regulation."

Epidemiologist Gideon Meyerowitz-Katz ran a statistical analysis of that study, and concluded it used flawed methodology because the report authors ran the tests 43 times to come to their conclusion.

"The issue is when you do a statistical test you flip a coin. If you flip enough coins you'll eventually get a heads. If you do enough statistical tests you'll eventually find positive results," he said.

"When you do that kind of test what you should be doing is what's called correcting for multiple comparisons. Basically, you do a statistical calculation that says this is the number of positive results I found, but this is the number of tests I did, how likely is it that those positive results are actually true? And they didn't correct for multiple comparisons.

"If you do any correction at all, you find that none of the results they found are statistically significant. Which means basically that it's likely the results that the IAAF found in their study are down simply to chance and don't describe a true finding."

The IAAF says affected athletes who want to continue competing against women must take medication, like hormonal contraceptives, to lower their testosterone levels to within the desired range.

Or if they choose not to medicate, they can compete against men, or potentially in a new intersex category which could be offered.

But there are concerns the IAAF is essentially re-introducing a modern form of sex testing, which in the 1960s included methods such as visual examination of female competitors' genitals, and even a 'naked parade'.

"It absolutely follows the prior procedures that have been called that (sex testing)," Dr Karkazis said.

"The sports' governing bodies understand that the public won't accept that. That's why they claim to have abandoned these kinds of policies in the 1990s. What followed in the wake of that was a reformulation under the cloak of science, an argument about testosterone and advantage.

"It's really a continuation of the long-standing scrutiny of all women athletes, for being appropriately feminine, not to present as too masculine, whatever that might mean."

'Take treatment and shut up'

Mr Carpenter is disturbed by the proposed solutions for female athletes who want to continue participating in the restricted events.

"I think that's a horrific thing. What it's actually saying is that if you're an intersex woman you should take treatment and shut up, or you're excluded. It's creating a situation where you either conform to medical norms about what it is to be a woman or you're out," he said.

"The IAAF and IOC have been doing this (gender testing) for more than 50 or 60 years and the outcomes have never been good. They've always been outcomes where women have been humiliated, lost housing, lost work, lost relationships. It's a terrible situation for women to be in."

IAAF president Lord Sebastian Coe is adamant the regulations are about fairness.

"The revised rules are not about cheating, they are about levelling the playing field to ensure fair and meaningful competition in the sport of athletics where success is determined by talent, dedication and hard work rather than other contributing factors," he said.

But Mr Meyerowitz-Katz has questioned why the IAAF isn't concerned about other natural advantages that athletes may have.