SII Focus 20th April 2016

Testosterone is not exclusively a male hormone

Testosterone is not exclusively a male hormone. It is produced in significant quantities by males and females – especially by elite athletes, who need it to aid muscle growth and recovery. The reason this drum needs banging, yet again, is because there has recently been speculation that Caster Semenya (pictured) is running faster not because she has trained hard, but because she may have stopped taking testosterone limiting medication.

Apart from being extremely unfair to a young athlete in her prime and leaving aside the issue that it may simply be untrue, there is no evidence that an elite athlete’s natural testosterone levels give them an unfair performance advantage.

Natural testosterone – cheating?

Externally administered testosterone is known as exogenous, and is the main ingredient in anabolic steroids, which are banned in sport as they artificially elevate the body’s natural testosterone levels, stimulating muscle growth. Testosterone naturally produced within the body is known as endogenous.

In a very simplified form, a person taking on exogenous testosterone is cheating, as it allows that person to artificially stimulate muscle growth. What is less certain is the impact that endogenous testosterone levels have on muscle growth, as this tied in with many other biological factors. What is very uncertain is the impact that endogenous testosterone has on athletic performance and whether it results in a competitive advantage.

Dutee Chand ruling

This uncertainty was the reason that the Court of Arbitration for Sport (CAS) suspended the International Association of Athletics Federations’ (IAAF) Hyperandrogenism Regulations on 24 July 2015. During the hearing of Dutee Chand’s appeal against the validity of the Regulations, the Panel was unable to conclude that hyperandrogenic female athletes – i.e. ones with elevated levels of endogenous testosterone – benefit from such a significant performance advantage that it is necessary to exclude them from female competition.

The CAS ruling also questioned the presumption that endogenous testosterone had the same effect on physiology as exogenous testosterone. ‘The panel considers the lack of evidence regarding the quantitative relationship between enhanced levels of endogenous testosterone and enhanced athletic performance to be an important issue’, reads the Chand ruling. ‘In order to justify excluding an individual competing in a particular category on the basis of a naturally occurring characteristic such as endogenous testosterone, it is not simply enough to establish that the characteristic has some performance enhancing effect. Instead, the IAAF must establish that the characteristic in question confers such a significant performance advantage over the other members of the category that allowing individuals with that characteristic to compete would subvert the very basis for having the separate category and thereby prevent a level playing field.’

The IAAF has until 24 July 2017 to provide scientific evidence outlining the degree of competitive advantage enjoyed by hyperandrogenic females, otherwise the rules will be declared void. It has yet to present any scientific evidence and, in the meantime, its Regulations have been suspended.

Show me the science

Both the IAAF and the International Olympic Committee (IOC) introduced hyperandrogegism regulations in 2011 after Semenya challenged a 2009 gender test on human rights grounds. Until recently, only the IAAF Regulations set a limit on the amount of endogenous testosterone a woman is permitted to produce. It chose the level of 10nmol/l, which sits at the lower end of the ‘normal’ male range.


The US University of Rochester’s online medical library states that the normal ‘male’ range for testosterone is between 9.7nmol/l and 38.1nmol/l; and between 0.5nmol/l and 2.4nmol/l for ‘females’. The US government’s National Library of Medicine agrees with the University of Rochester’s ranges with regards to ‘women’, but puts normal ‘male’ levels at between 10.4 nmol/l and 34.7nmol/l. According to research undertaken in the US in 2004, the IAAF limit of 10nmol/l is at the lower end of the normal range for males over 40.

As these different analyses show, these levels can vary with age, but also due to occupation. A 2014 study, ‘Endocrine profiles in 693 elite athletes in the post-competition setting’, found that 16.5% of the ‘male’ athletes had low testosterone levels, and 13.7% of the ‘females’ had high testosterone levels, ‘with complete overlap between the sexes’. The report concluded: ‘The IOC definition of a woman as one who has a ‘normal’ testosterone level is untenable’. In other words, elite athletes have testosterone levels that differ widely from those that might be considered ‘normal’ in the general public population.

Interestingly, even the IAAF’s own research found that ‘there is no clear scientific evidence proving that a high level of T [testosterone] is a significant determinant of performance in female sports’. It therefore appears to be legitimate to question why a limit of 10nmol/l has been placed on female athletes, when it appears that there is no scientific evidence that anything above this limit – which appears to be arbitrary – would offer a competitive advantage.

Caster Semenya

Caster Semenya, the South African runner who was 19 at the time of her gender test, is now 25 and appears to be a good bet to win medals at the Rio 2016 Olympics. She has recently run the fastest time in the world this year in the 400m, and also won the 800m and the 1,500m, becoming the first athlete in the history of the Athletics South Africa (ASA) National Championships to win all three titles.

The suggestion is that Semenya is running so fast because she is no longer required to keep her endogenous testosterone levels under 10nmol/l, as the IAAF’s Hyperandrogenism Regulations have been suspended. However, the Regulations were suspended precisely because of the lack of scientific evidence that high endogenous testosterone levels confer a performance advantage in female sport.

Gender & abuse

Once again, this appears to come down to gender. Semenya was sanctioned on the basis of a gender test and this is what she continues to be judged on. Semenya can no longer enjoy being a remarkable athlete. She must endure accusations and allegations every time she competes, all of which are based on the perception that some women are more ‘male’ than others and therefore enjoy a performance advantage, even though such a perception is based on bad science.

The leak of Semenya’s gender test results to the media in 2009 was a serious breach of confidentiality, and is one that has never been fully investigated by the IAAF, which has a duty to protect its athletes. We still don’t know who gave that information to the Australian media or why. It may even be inaccurate.

Proof that the IAAF Regulations are about gender and not endogenous testosterone levels arrived in 2013, when a study was published which found that surgery was performed on four young athletes, who were found to have a mix of male and female anatomical features. The athletes, aged 18-21, were told that the surgery would lower their endogenous testosterone levels and allow them to compete at London 2012.

However, all the athletes had medical procedures that had nothing to do with this: reductions to the size of their clitorises, ‘feminine’ remodelling surgery and oestrogen replacement therapy. This surgery was entirely unnecessary. It was not due to any gender identity issues, had no basis in relation to sport or physical performance, and was based purely on cosmetic ideals put forward by sport.

Even worse, as these young women had no ovaries and had surgery to remove undescended testicles, they have had their ability to naturally produce testosterone removed. Scientists have found that when the body loses its ability to produce androgens, it loses its ability to maintain itself, as androgens have over 200 daily functions in the human body.

In effect, these women have been medically damaged by sport and must now take synthetic testosterone for the rest of their lives, or suffer ‘complete hormonal deprivation’, which causes a number of health issues outlined in this article. Again, no investigation has been carried out into who is culpable for medically harming these athletes.

Not an isolated issue

Another female athlete who has suffered in this way is Dutee Chand, who was not selected for the Glasgow 2014 Commonwealth Games after the Athletics Federation of India (AFI) found that her endogenous testosterone levels were above 10nmol/l. Paragraph 248(d) of the Chand ruling revealed that far from being a rare occurrence, the IAAF has dealt with over 30 cases to date. As the IAAF’s Hyperandrogenism Regulations came into force in May 2011, that is over ten cases per year.


Nine different variations on the basic female (XX) and male (XY) chromosome pairings are possible. Scientific research dictates that as much as 2% of live births may involve some kind of ‘intersex’ condition. Yet sport still insists that everyone must fit into two boxes.

Double jeopardy

Caster Semenya is now at risk for becoming the first athlete to be tried twice for the same gender ‘crime’, even though she hasn’t committed an offence. In November 2015, the IOC released a Consensus Statement which urged sport to ‘revert to CAS with arguments and evidence to support the reinstatement of its hyperandrogenism rules’. IOC President Thomas Bach has since suggested that the IOC will attempt to introduce some form of limitation on endogenous testosterone ahead of the Rio 2016 Olympics, despite the IAAF ruling in the Chand case.

If such limits are introduced ahead of Rio, Semenya could find herself locked out of the Olympics. However, were this to happen, she would have a strong legal case. ‘Despite the CAS decision to suspend the IAAF Hyperandrogenism Regulations, the IOC has failed to announce whether it will follow this precedent and refrain from implementing its own hyperandrogegism regulations at the Rio 2016 Olympic Games’, reads a 9 February letter sent directly to Bach by the legal team that represented Chand. ‘The IOC’s failure is most disconcerting given that the IOC’s previous Hyperandrogenism Regulations were developed conjointly with the IAAF and were based on the same premise and scientific studies that the CAS found inadequate to justify the Regulations’.


In conclusion, nobody actually knows for sure whether Semenya does have elevated endogenous testosterone. Interestingly, in 2009, when a ‘source familiar with the IAAF inquiry’ spoke to Australia’s Daily Telegraph about tests conducted on her, they were happy to discuss Semenya’s genitalia, but insisted on their own anonymity.

Secondly, even if she does have elevated endogenous testosterone levels, there is no scientific evidence to support the IAAF’s theory that this confers an unfair advantage. Thirdly, even if it did confer a performance advantage, is it fair to limit something naturally produced by her body? After all, we don’t sanction Usain Bolt for his extraordinary step length of 2.44m, or 6’4” Michael Phelps for his extraordinary large arm reach of 6’7” and his size 14 feet, which have been found to give him a 10% advantage over competitors.

Both Semenya and Chand have been sanctioned for something their bodies produce naturally. Other women have been medically harmed due to their natural physiology. Surely, the ethos of sport is about making the best of your body’s natural advantages? Even if the IAAF were to provide evidence that the advantages conferred by endogenous testosterone were too great to allow, then where should sport draw the line? Should we start looking at genetics? Do we really want to go down that road? Surely the sensible solution would be to find a way of accommodating those who wish to take part in sport – whatever their physiological make up.

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