Limiting the testosterone levels of professional female athletes is fair because the hormone can give them man-like strength, according to scientists.
Experts have backed up a ruling from the International Association of Athletics Federations (IAAFS) requiring women to keep their testosterone within set limits.
The ruling came in a case about South African runner Caster Semenya, who lives as a woman but was born intersex, making her biologically both male and female.
Female athletes are already more likely to have high testosterone, researchers said, and a biological spike could further add to its performance-enhancing benefits.
The controversial cap made on testosterone levels in female athletes has been regarded as fair by scientists. Pictured: Runner Caster Semenya, 28, who will need to take medication to reduce her naturally occurring testosterone levels if she wants to continue to compete. Pictured with her gold medal in the Women’s 800m Final at the 2018 Commonwealth Games
Researchers from the Karolinska Institutet and Karolinska University Hospital in Sweden looked through past research to examine testosterone’s effects.
They claimed high levels of the hormone in female athletes could boost their performance so much their body was more like a man’s than a woman’s.
Professor Angelica Linden Hirschberg, who led the review, said there had not been enough studies into the effects of testosterone on women’s sporting ability.
But what evidence there was confirmed women with particularly high levels of the hormone – known as the male sex hormone and as much as 20 times more abundant in men – gifted women with muscle mass and endurance comparable to men’s.
‘Elite female athletes want to compete fairly against other women, not those who have a more male physiology,’ Professor Hirschberg said.
‘In circumstances where women have high testosterone levels they may have a powerful advantage.’
The professor and gynaecologist said it was tricky to put a number on what should be considered a normal level of testosterone for a woman.
Health conditions such as polycystic ovary syndrome can boost levels of the hormone in a woman’s blood but would likely give no unfair performance benefit.
And those who naturally have higher testosterone for genetic reasons are over-represented in sport, she said, which had to be accounted for in the new rule.
Ms Semenya was subjected to a sex test in 2009 when people claimed she was a man after testing found higher than usual levels of testosterone in her blood. Pictured as she competes in the women’s 800m during the IAAF Diamond League competition on May 3, 2019 in Doha
The IAAF now says all women wanting to compete in running events over distances between 400m and a mile must have testosterone lower than 5nmol/L.
A normal level for healthy women is up to 1.7nmol/L, while men’s is between 7.7nmol/L and 29.4nmol/L.
The women’s athletic benchmark is more than twice as high as a normal level for ‘fairness’ and to take into account the fact athletes are likely to have unusual levels, Professor Hirschberg said.
Therefore, athletes with what the IAAF calls ‘differences of sexual development’ which make their testosterone extraordinarily high, such as Ms Semenya, must take medication to keep their testosterone down.
When Ms Semenya was found to have illegally high testosterone the limit for women was 10nmol/L – well above normal for a woman and into the range of a healthy man.
Professor Hirschberg added: ‘In the interests of fairness in sport for all, a policy that responds with sensitivity to those who may have a condition causing high testosterone is needed.
‘We have focused specifically on defining the levels that really confer additional advantages on strength and speed in women, and setting an appropriate limit for competitive fairness.’
Professor Hirschberg’s claims have been met with criticism calling them ‘oversimplified’.
Dr Sheree Bekker, from the University of Bath, told MailOnline: ‘This kind of statement is based on outdated and incorrect views of testosterone as the “male” hormone, when in fact both men and women need testosterone to function healthily.
‘Further, given the many other variables that influence athletic performance, saying that higher testosterone equals better performance is not as quite as simple as it would seem on the surface.
‘It appears that this paper aims to show that the IAAF regulation testosterone cut-off point of 5nmol/l is not arbitrary, but rather aims to include women with polycystic ovarian syndrome but to exclude women with differences of sex development.
‘The glaring inconsistency here is that we simply cannot distinguish between these groups based on blood testosterone alone, never mind determining who is sensitive to testosterone and what supposed “performance advantage” that confers.’
Professor Hirschberg will present her research at the European Society of Endocrinology meeting this week.
HOW CASTER SEMENYA’S CASE CAUSED CONTROVERSY
The South African runner Mokgadi Caster Semenya, 28, was banned from running for almost a year in 2009 after being found to have higher than usual levels of testosterone in her body.
Critics claimed she was a man because of her outstanding performance which led to her being subjected to a sex test.
The results were never published but are believed to have shown she was born with both female and male biology.
Caster Semenya has been at the centre of a row over a new rule by the IAAF that restricts testosterone levels in female runners. Pictured during the women’s 800m race at the IAAF Diamon League competition, May 2019
She was allowed to return to competition as a woman and has since won Commonwealth and Olympic gold medals.
Ms Semenya tried to take legal action against the rule, but The Court of Arbitration for Sport (CAS) rejected Ms Semenya’s challenge in May 2019.
They said the decision was ‘necessary, reasonable and proportionate’ to make sure competition was fair, but added it had ‘serious concerns as to the future practical application’ of the new rules.
Ms Semenya has expressed how unfair she felt the rules were and that all she wanted was to ‘run naturally, the way I was born’.
To adhere to the regulations, Ms Semenya would either have to start taking medication in order to defend her world 800m title later this year or to compete in 5,000m, which is not covered by the IAAF’s regulations.
Athletics South Africa (ASA) said it was ‘reeling in shock’, and South Africa’s sports minister Tokozile Xasa said that Caster had been ‘targeted’ and called the proposed IAAF rule a human rights violation.
Athletics South Africa, the country’s track and field body, will appeal the decision by the Court of Arbitration for Sport.