What athletes, fans, and the sports media don't understand about human growth hormone.

The state of the universe.
March 24 2007 7:50 AM

The Growth Hormone Myth

What athletes, fans, and the sports media don't understand about HGH.

Illustration by Rob Donnelly. Click image to expand.

The sports world's latest doping scandal began last month, when federal and state agents raided a seedy office building in Jupiter, Fla., and a pharmacy in Orlando. According to a pair of embedded reporters from Sports Illustrated, the investigators busted up a "massive illegal distribution network" for performance-enhancing drugs; the fallout, they say, "promises to rock sports."

Daniel Engber Daniel Engber

Daniel Engber (@danengber) is a columnist for Slate. Send him an email at danengber@yahoo.com.

It's worth noting that what SI touted as a "Steroid Sting" has produced very little evidence of, well, steroids. Instead, the disclosures and public shamings have focused on human growth hormone, an almost-undetectable substance that has recently replaced anabolic steroids as the trendy, performance-enhancing boogeyman. SI's ongoing series of reports has fingered baseball players Jerry Hairston Jr. and Gary Matthews Jr., pro wrestlers Edge and the Hurricane, and boxing champion Evander Holyfield for ordering HGH. Even fictional athletes have had their reputations tainted by the stuff. A few weeks ago, Sylvester Stallone, portrayer of Rocky Balboa, was charged with importing 48 vials of synthetic growth hormone into Australia.

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The media haven't spent much time making a distinction between HGH and steroids. An AP story, titled "After BALCO, Another Steroid Scandal," glosses over any differences between the two, drawing a straight line from the BALCO investigation to the busts in Florida. But Jerry Hairston isn't Barry Bonds. Sure, both of these guys probably took banned substances in an effort to boost their stats, and both were involved in major drug busts involving large numbers of Major League players. But it's just plain wrong to put growth hormone in the same category as anabolic steroids. In the sports version of the war on drugs, Bonds was shooting heroin while Hairston was smoking marijuana.

What's the difference between steroids and HGH? For starters, we know that a baseball player can beef up on steroids and improve his athletic performance. But most clinical studies suggest that HGH won't help an athlete at all. The other key difference is that while steroids cause a bevy of nasty side effects—testicular shrinkage, an increased risk of stroke—taking HGH doesn't seem to be that bad for you.

If growth hormone doesn't help, why are athletes breaking league rules to get it? And if it doesn't hurt, why are there league rules against it in the first place? Widespread belief in the efficacy of HGH dates back to a 1990 article in the New England Journal of Medicine. A research team led by Daniel Rudman of the Medical College of Wisconsin gave regular growth hormone injections to a dozen men over the age of 60. At the end of the six-month treatment period, the test subjects had denser bones, thicker skin, less fat, and more lean body tissue. The paper likened these effects to a reversal of "10 to 20 years of aging."

The Rudman study soon spawned a mega-industry of rejuvenation clinics and anti-aging drug regimens. Healthy people secrete growth hormone naturally throughout their lifespan, with the highest concentration coming during adolescence. But HGH levels fall off as we get older; 60-year-olds might make half as much growth hormone as they did in their 20s. In 1996, the FDA approved growth hormone as a replacement therapy for adults whose HGH secretions had fallen below normal levels.  Since then, immersion journalists have written paeans to the drug that jibe with Rudman's findings. In 2003, a writer for Outside claimed it improved his eyesight and made a scar on his forehead disappear. Last January, a GQ guinea pig said it filled him with "youthful radiance," deepening his voice and renewing his interest in Internet pornography.

Clinical researchers have been a bit less sanguine. You don't need a Ph.D. to find serious flaws in the Rudman study—no one in the control group received a placebo, for example. Still, a recent review in the Annals of Internal Medicine found that better studies have produced similar results: At the very least, treatment with HGH does seem to reduce body fat and increase muscle mass. Growth hormone may not lengthen your lifespan, but it can certainly improve your looks. (While HGH isn't as bad for you as anabolic steroids, it does have some minor side effects. Click here for more information.)

That doesn't mean very much for athletes: A chiseled physique won't help you hit a baseball or throw a punch. So far, no one has been able to connect the increase in lean body tissue caused by HGH with enhancement of athletic performance. Unlike steroids, growth hormone hasn't been shown to increase weight-lifting ability; in the lab, it has a greater effect on muscle definition than muscle strength. And it doesn't seem to help much with cardiovascular fitness, either.

So, why do so many athletes take HGH? One possibility is that the drug really does enhance performance but that the effect is too subtle to measure in a controlled setting. An elite athlete might be able to detect very slight improvements in strength and agility that would be invisible to lab scientists or statistical tests. At the highest levels of sport, a tiny edge can make a big difference. Athletes might also derive some added benefit by mixing HGH with other drugs—anti-aging doctors often prescribe growth hormone in combination with testosterone.

It's also possible that baseball players aren't using HGH to beef up at all. Almost everyone who gets caught red-handed claims they were using the drug to recover from an injury. This might be more than a ploy to win sympathy: Some doctors believe that growth hormone can speed up tissue repair. There isn't much clinical work to support this idea, however. One study even found that HGH actually shortened the lifespan of patients in an intensive-care unit.