What Makes A "Female" Athlete? The Answer Isn't So Simple

After South African middle-distance runner Caster Semenya won gold in the 800 meters at the International Association of Athletics Federations (IAAF) World Championships in 2009, the IAAF subjected her to "femininity testing" to evaluate the levels of testosterone in her blood. The testing found that Semenya has a condition called hyperandrogenism, which causes her to naturally produce higher amounts of testosterone than most other cisgender women. Upon discovering this, the IAAF suspended her from competing in track and field competitions for eight months, and then went to work developing new rules that detailed what type of woman was allowed to compete in the association's races — and thus, a controversy was born.

Now, as the IAAF releases new, even more stringent guidelines, the questions Semenya's story raised are more pertinent than ever. Namely, does having naturally elevated testosterone levels give women a competitive edge in sports?

The IAAF believes it does, so much so that the association has recently doubled down on regulations that have already been called into question. In 2011, the IAAF released regulations that stated that women like Semenya could no longer run in mid-distance races (anything between 400 meters and one mile) unless they artificially lowered the amount of testosterone their bodies produced. Originally, the IAAF set the acceptable androgen ("male" hormone) levels for women at 10 nanomoles per liter (nmol/L) of blood, which is roughly the lowest amount that cisgender men produce. On Thursday, the organization made their eligibility requirements even stricter, lowering the acceptable androgen levels for women runners to 5 nmol/L.

The move has many people questioning whether the IAAF's attempt to make women's running more fair actually unjustly excludes some women (and intersex people). As The New York Times points out, this new rule could effectively end some elite female runners' careers. Women who naturally produce 5 nmol/L of testosterone or more have three options under this new rule: They can take medication similar to a hormonal birth control pill to lower the amount of testosterone they produce, they can compete with men, or they can stop racing in IAAF races (which means they'd have no chance of making it to the Olympics).

The IAAF claims that the new rule is necessary for the sake of fair play. According to a statement from the IAAF: "The revised rules are not about cheating, no athlete with a DSD [Difference of Sexual Development] has cheated, they are about leveling 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." And some medical professionals do say that high levels of testosterone could give female runners an advantage over their peers.

"Five nmol/L is three times greater than the upper limit of normal in women," says Clare Flannery, MD, an endocrinologist at Yale School of Medicine. It's uncommon for women to have testosterone levels that high, even if they have a condition like polycystic ovary syndrome (PCOS), which causes elevated androgen levels, she says. Because testosterone helps in muscle growth, as well as in the production of hemoglobin (which carries oxygen from the lungs to the body's tissues), elevated levels could give women like Semenya a boost. "Women with significantly higher levels of testosterone could potentially have greater muscle strength and greater oxygen carrying capacity. That would be an advantage in running," Dr. Flannery says.

Yet, some people argue that greater levels of testosterone won't give runners a significant enough advantage to exclude these women from the sport. In 2015, Indian sprinter Dutee Chand fought the IAAF's first hyperandrogenism rule through the Court of Arbitration for Sport (CAS) and won. The CAS stated that hyperandrogenism would have to give women a 10% to 12% advantage over other female runners, otherwise it's unfair to deem elevated testosterone such an important factor in "leveling the playing field."

As a result of Dutee's case, the CAS suspended the IAAF's hyperandrogenism rules for two years and asked the organization to find proof that elevated testosterone gives women a significant edge over their competition. In 2015, research funded by the IAAF found that hyperandrogenism could give women runners an advantage between 1.8% and 4.5%, which isn't large enough to make a real difference, according to the CAS's ruling.

In the ensuing years, the IAAF has continued to fund research into hyperandrogenism in sports. The organization claims that a 2017 study found sufficient evidence to support cutting the original testosterone restrictions in half, NPR reports. Athletics South Africa, which represents Semenya, posted a statement to Twitter on Thursday saying that they would be studying the new IAAF regulations to make sure they're in line with the CAS's recommendations.

The question is: With so many variables that could give one person a leg up over another, why is the IAAF so worried about testosterone?

As bioethicist Silvia Camporesi pointed out in a 2017 op-ed for Aeon, most athletes have some sort of genetic advantage over the rest of the population (and definitely some more than others), and athletes who have the monetary resources to train at high-end facilities could also have a leg up over those who can't afford that sort of training. Someone could even have an advantage simply based on where they live. "Living and training at a high altitude, then racing at lower altitudes would also have the effect of increased oxygen carrying capacity," Dr. Flannery says.

On top of all this, there's one major aspect the IAAF seems to be forgetting: Cisgender men with elevated testosterone also benefit from above-average T levels. "Higher testosterone levels will generally be an advantage in both men and women," Dr. Flannery says. Cisgender men produce between 7.7 and 29.4 nmol/L of testosterone, according to the IAAF. So, it would stand to reason that male athletes on the higher end of that spectrum would have an advantage over male athletes on the lower end. If testosterone is being positioned as the "biggest" predictor of athletic performance, then shouldn't we be putting men into "testosterone classes" similar to the weight classes used to keep wrestling matches fair?

Maybe that seems like a ridiculous solution; and the truth is, "leveling the playing" field for men would probably be much more complicated than that. But doing the same thing for women isn't simple, either. (Not to mention, dividing sports by binary gender completely leaves out intersex and gender nonconforming people.) The IAAF may have pure intentions to make women's competitive running as fair as possible — and, honestly, making sports more fair does sound like a good thing — but policing gender through "femininity tests" misses the mark. It's a Band-Aid solution to a much more complicated problem.