If you’re thinking of popping thyroid medication to get an athletic edge, go ahead; it probably won’t do you any good. That’s the message from the World Anti-Doping Agency, which declined to add thyroid meds to its prohibited substances list for 2016—a decision that experts agree is legit, despite lobbying by both the U.S. Anti-Doping Agency (USADA) and UK Anti-Doping to get thyroid meds banned.
Their desire for the ban likely stems from issues linked to Nike’s famous running coach, Alberto Salazar, and the large number of his athletes who take thyroid medication. In the spring of 2013, The Wall Street Journal published a story about Salazar’s preferred endocrinologist, Dr. Jeffrey S. Brown, and his penchant for diagnosing top runners with hypothyroidism, or underactive thyroid.
Then Salazar came under fire again early this summer for, among other tings, allegedly “giving athletes prescription medications they either didn't need or weren't prescribed in hopes of gaining a competitive advantage from their side effects”—including thyroid hormone, Pro Publica’s David Epstein reported.
But a slew of diagnoses—and a questionable use of medicine—still doesn’t mean athletes are getting a performance advantage from taking thyroid hormone, whether they need the medication or not.
To understand why, first you have to know a little about your thyroid gland. Located at the base of your neck, it produces hormones that help regulate metabolism and everything related to it including your heart rate, blood pressure, and body temperature. If it is underactive, metabolism can slow, causing weight gain and fatigue, and it’s long been thought that taking thyroid hormone when you’re healthy can aid in weight loss and/or alertness.
For example, former BALCO head, Victor Conte, who was accused of supplying several athletes with steroids, wrote that he’d given British sprinter Dwain Chambers thyroid hormone to “help accelerate the basic metabolic rate before competitions. The purpose was to reduce sluggishness and increase quickness.”
The thing is, no science supports the idea that short or long-term use of thyroid medication provides these types of benefits. “In general, taking excessive thyroid hormone is disadvantageous to athletic performance,” says Harvard endocrinologist and world-renown thyroid expert Dr. Jeffrey Garber. “It really screws people up. It’s a catabolic hormone—it breaks down things, specifically muscle.”
As proof revving up your thyroid can have disastrous effects, Garber points to two athletes who have overactive thyroids caused by an immune disease: three-time Olympic champ sprinter, Gail Devers, and golf legend Pat Bradley. Both women nearly lost their athletic careers when they suffered massive weight loss and weakness (Devers), and shaking hands and rapid heartbeat (Bradley), issues typically associated with excess thyroid hormone.
Healthy endurance athletes, it’s been thought, can train their way to hypothyroidism. That would explain why so many top athletes get diagnosed with it, but even training-induced hypothyroidism, which Gerber agrees can happen, doesn’t necessarily warrant treatment with medication.
“The question is are changes adaptive or maladaptive?” Gerber says. “In other words, if you start to slow down your metabolism because you’re overtraining, is that a bad thing?”
It’s likely the body’s way of preserving itself—of trying to prevent more muscle breakdown, in which case an underactive thyroid is a sign to back off, not to introduce more thyroid hormone. But taking medication for overtraining-induced hypothyroidism can lead to exactly what Salazar may be trying to prevent in his athletes: weight gain. “Some people gain weight when they take a little too much thyroid hormone because their appetite goes up and they eat more than their metabolism can handle,” Gerber says.
Bulking up is hardly a performance enhancer in runners, and potential to enhance performance is one of three criteria a substance must meet to be considered for WADA’s prohibited list. The other two: it must pose a potential health risk to the athlete, or violate the spirit of the sport.
Here’s where thyroid hormone gets a little dicey. For some athletes, taking a quick hit of it before a competition, as Conte recommended for Chambers, might improve alertness, though it would also accelerate heart rate and could induce tremors. “It’s like amphetamine, the short-term effect,” Gerber says. “How well would you do if you had four cups of coffee before you got on your bicycle? There’s probably somebody out there who would do better in a competitive match if they took a stimulant,” but the boost their getting is mental, rather than physical. Currently, WADA allows stimulants, and caffeine, but in specified concentrations. Perhaps that’s how thyroid hormone should be regulated in the future.
So while USADA and UKAD are right in believing that some athletes are violating the spirit of the sport by taking unnecessary thyroid medication, the hormone’s side effects may be punishment enough—WADA doesn’t need to intervene.
Gerber supports WADA’s decision for now. “Hypothyroidism is a real condition that requires treatment,” he says. “It’s not fair to penalize people who need to take it to live a normal life.”