The mystery of testosterone and women’s sport

When sports scientist Dave Hamilton set out to monitor the testosterone levels of an international women’s hockey team it was with the aim of measuring how the athletes were coping with their new heavier training load. Hamilton took three weeks’ worth of daily salivary samples from the players, one in the morning, and one in the afternoon after physical activity. The study did not throw up any red flags around their training schedules, but it did yield some unexpected results.

“What we found was that relative to a sedentary population, [the women] had high testosterone levels, ”said Hamilton, who now works in a similar high performance role at the Tampa Bay Buccaneers. “We also found people who were on oral contraception, versus those who weren’t, had lower testosterone levels.” In fact, women who weren’t on oral contraception had testosterone concentrations that were on average 35 percent higher than those who were on the pill.

It is an intriguing insight into the various levels of testosterone among sportswomen. In an age where the ‘T’ word has become the center of a fierce debate around whether trans and differences in sex development (DSD) athletes should be allowed to compete in women’s sport – with testosterone levels often the determining factor – the hormone is often misunderstood as having an impact exclusive to men.

Much of the lack of understanding stems back to the historical underinvestment in sports science research on women.

Unlike the current testosterone trans policies in sport, which measure levels in the blood, Hamilton’s study focused on the salivary or ‘free’ testosterone, which yields a much smaller amount of the hormone. The findings uncovered sharp changes in response to a diverse range of stimuli – from exercise and music, to coaching feedback, sleep, being in a group setting or on your own.

“We guided our program knowing that testosterone responds to a physical and also an environmental stress,” explained Hamilton. “There’s been a lot of research that shows when you win, testosterone levels go up, when you lose, testosterone levels go down. If you think a regular female sits around 20 to 40 pg / ml of free testosterone, you could go from a recording of 25 to 55 pg / ml. ”

There was, however, another significant finding. “We had a large portion of our team reporting testosterone levels in the range of 80 to 100pg / ml, which is in line with the average male testosterone level,” said Hamilton. “There was also nothing in our data to suggest that if ‘x’ had the highest T levels she was the best athlete. That just wasn’t a thing. ”

On the contrary, high testosterone levels in athletic female populations – entering male ranges – have been found previously, as demonstrated by a 2014 study published in the journal Clinical Endocrinology.

Based on blood samples of 693 athletes, the study found that 16.5 percent of men had low testosterone levels, whereas 13.7 percent of women had high levels, with a complete overlap between the sexes. The paper criticized the International Olympic Committee’s then definition of normal testosterone levels for a woman as “untenable”.

“There are a lot of men with low testosterone who are good athletes,” said Peter Sonksen, an Emeritus Professor of Endocrinology at St Thomas’ Hospital and King’s College, London, who co-led the study and research for the International Olympic Committee. eventually led to the development of an anti-doping test for Human Growth Hormone.

“And there are a lot of women with very high testosterone who are also good athletes. The simple issue is always that testosterone makes them super athletes, but that’s b ——-.

The issue is so complex and polarizing that – largely due to a lack of data – the IOC now allows global sporting federations to determine their own trans policies. It had previously recommended that trans women suppress testosterone levels to under 10 n / mol per liter for at least 12 months in order to compete, meanwhile the Union Cycliste Internationale stipulates cyclists must keep below a level of 5 nmol / L for a period of at at least 12 months. “It’s an incredibly sensitive area and one where they’re being deliberately simplistic and messing up the science,” added Sonksen.

The IOC defended its approach towards the “evolving topic” of trans women in sport and highlighted how new studies have not provided a consensus on how testosterone affects performance across all sports. It added: “There is no single right answer from science at this stage as the scientific evidence needs to be specific to each sport or discipline and how competitive advantage is to be measured there.”

So minute is the trans women population that, nearly two decades after the IOC originally mandated trans athletes could compete in the Olympics providing they underwent gender reassignment surgery, sport is still in the early stages of its fact-finding mission to understand whether trans women in sport possess an advantage over cis women. At the heart of the debate – which intensified earlier this month after trans cyclist Emily Bridges was barred from riding in the National Omnium Championships – is testosterone.

One study published last year in the British Journal of Sports Medicine found that trans women who underwent hormone therapy for one year continued to maintain an athletic advantage, despite a 15-31 percent decline in physical performance.

Based on transgender men and women serving in the U.S. military, it found the 15–31 percent athletic advantage trans women displayed over their cis women counterparts prior to starting gender affirming hormones declined with feminizing therapy. However, trans women still had a nine percent faster mean run speed after one year of testosterone suppression.

“It becomes a discussion of how low, for how long,” says Dr. Christina Marie Roberts, a pediatrician and associate professor at the University of Missouri-Kansas City who led the research. She points to a variation that exists among cis gender women, which has flown under the radar in the context of discussing fairness in sport.

“The IOC originally picked 10 nmol / l because that’s the highest naturally occurring testosterone levels in women. Some women with PolyCystic Ovarian Syndrome will have higher levels of testosterone than other women. Testosterone, wherever it’s coming from, is an advantage, so there is going to be some advantage in women’s sport anyway. ”

Competing in the mixed-gender sport of motor racing, Charlie Martin – the British racing driver who hopes to become the first transgender driver to compete in the Le Mans 24 hours – believes understanding of testosterone in trans women is often misunderstood. Having undergone a medical transition, which included full gender reassignment surgery, her body does not produce testosterone in any real quantity. “It’s simple stuff like that which most people don’t think about,” says Martin, in reference to the debate about whether trans women should compete in female sport.

She adds: “I’d say my strength is in line with that of a cis gender woman who does a similar amount of training to me and eats and trains well. That’s my experience and the experience of pretty much every trans woman I know. ”

Leading the research in this country, is an ongoing study – in which Bridges is participating – at Loughborough University. Dr. Emma O’Donnell, a senior lecturer in exercise physiology there, highlights the challenges of the work. “With such a small transgender athlete population to draw from, and the variations in the physiological demands of different sporting disciplines, unfortunately it will be some years before we have the data required to inform sporting bodies to allow them to create evidence-based guidelines regarding transgender sports participation. ”

O’Donnell says that testosterone remains a vital element to the study. “Testosterone is an important parameter to consider,” said O’Donnell. “Testosterone levels increase almost 20 fold during male puberty, marking a time of significant physiological change in males. The testosterone exposure that an adult trans woman will have been exposed to before commencing testosterone-lowering hormone therapy is therefore an important consideration when trying to understand the effects of hormone therapy on athletic performance. “At this time, these effects remain unclear.


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