Do Trans Athletes Have An Advantage According to Science?

Given the constant battle we have around here I thought I’d see if I could find something to actually talk about on the subject. Hormone therapy makes a lot more difference than most people realize. A reasonable discussion may not happen, but at least I will have given it a try. Hope springs eternal. The article is a little older, but still relevant.

What does the science tell us about trans athletes in elite sport?

Few studies have been done on trans people’s athletic performance — and, to date, there are no published studies on trans athletes participating at the elite level, say experts. But some papers have been published in the lead-up to the Olympic Games.

One study, published in 2020, looked at US military personnel who transitioned while in service and found that trans women maintain an edge after one year of feminizing hormone therapy, which usually includes suppressing testosterone levels and boosting estrogen.

The research was carried out by Dr. Timothy Roberts, a pediatrician and associate professor at the University of Missouri-Kansas City, and his colleagues. They found that trans women who underwent hormone therapy for one year continued to outperform non-transgender women, also known as cisgender women, though the gap largely closed after two years. But even then, trans women still ran 12% faster. 

Do Trans Athletes Have An Advantage According to Science?

Roberts, however, suggested the difference in running times needs additional perspective. “It was a 12% advantage after two years in run times. But to be in the top 10% of female runners, you have to be 29% faster than the average woman. And to be an elite runner, you’ve got to be 59% faster than the average cis woman,” he told DW. 

Another study, carried out by sports scientist Tommy Lundberg, found that trans women who underwent feminizing hormone therapy generally maintained their strength levels after one year. 

Do trans women have an advantage when competing in elite sports?

Without hormone therapy — yes. But even with hormone therapy, current research suggests trans women still maintain an edge in strength.  

“Pretty much any way you slice it, trans women are going to have strength advantages even after hormone therapy. I just don’t see that as anything else but factual,” said Joanna Harper, a medical physicist at Britain’s Loughborough University.  

Strength is one of several key factors — including explosiveness, endurance and lean body mass — that determine whether an athlete has an edge.

But Harper, whose research focused on trans runners like herself, rejects the idea that trans women competing in sport would have an “unfair” advantage, noting that there are many other factors that go into shaping how an athlete performs — including hand-eye coordination and technique, which are necessary for excelling in sports like golf. 

One major factor is hemoglobin levels — which is the most important physiological factor when it comes to endurance sport. Hemoglobin in the blood transports oxygen throughout the body, including to the muscles. Since hemoglobin levels follow testosterone levels, non-transgender men tend to have higher hemoglobin levels than cisgender women. But Harper’s study found that testosterone suppressants reduced hemoglobin levels in trans women to that of cisgender women, thus eliminating the advantage. 

For Tommy Lundberg, whose research at Sweden’s Karolinska Institute focuses on skeletal muscle strength of trans people receiving hormone therapy, the advantages for trans women in strength are to the point where fairness cannot be ensured in most sports.

“The big problem right now is that the [hormone] therapy itself doesn’t really remove the advantage to an extent that you can claim that fairness has been achieved,” Lundberg told DW. “And actually, the IOC (International Olympic Committee) states that the overriding objective is, and remains, the guarantee of fair competition. That’s what they say in their guidelines. So that’s the problem right now: They don’t go hand-in-hand.”

In another paper Lundberg co-authored that looked at untrained trans women, Lundberg and his colleague found that “muscular advantage enjoyed by transgender women is only minimally reduced when testosterone is suppressed.”

The study, like any other — including Roberts and Harper’s — has its limitations. Harper, who had also done a review of a similar set of studies to Lundberg’s, said both of their studies found a “fairly modest change” in strength in non-athletic trans people. “But their review made it seem more definitive than our review did,” she said. 

“If you are looking for information on cisgender athletes, you’d never use studies on non-athletic trans people. You just wouldn’t do that. It’s just that we don’t have any data on trans athletes. So I think you have to take the results with a certain grain of salt.”

What is the recommended testosterone for trans women to compete?

This is a thorny issue that sports scientists disagree on. The “normal” healthy range for cis women is between 0.3 and 2 nmol/L, according to Mayo Clinic estimates — though they vary among labs. Women with polycystic ovarian syndrome tend to have higher testosterone levels, which can reach 5.2 nmol/L. “Healthy” male testosterone ranges from 8.3 mnol/L to 32.9 nmol/L

The IOC’s regulations say trans women can compete if their testosterone levels in serum are at 10 nanomoles per liter for a year for at least 12 months prior to their first competition.

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