So let me get this straight: HGH enhances the development of "lean body tissue" (check-out those pecs!) but does not enhance athletic performance, which would require "strength and cardiovascular fitness." Last I checked "lean body tissue" was also known as muscle, and muscle was the source of strength, and a stong heart muscle was the foundation of cardiovascular fitness.

As for HGH side-effects, can we not have a few words about all those ridiculously oversized lower jaws, and neanderthal brows we see on all-too-many professional athletes?

Slate has completely missed the forest for the trees. They were so concerned with pointing out the differences between roids and HGH they lost sight of the fact they're very similar. And in the midst of all the doping scandals, it's certainly been keeping me up at night thinking about how writers aren't keeping them exactly straight. It's a huge insult to accuse a guy of being on HGH when he's actually just on steroids.

I think what the writer means and what I understand of HGH is that it makes your muscles "more cut" or appear more defined rather than actually bulking up your muscles as anabolic steroids do.

In other words: its mainly a cosmetic change.

Except that isn't the whole story with HGH. As the name implies, it causes your body to grow. One well-known side effect is it can cause parts of your body like your head and feet to suddenly grow. (This is often brought up about Barry Bonds because his shoe and hat sizes both went up by a couple sizes after he joined the Giants--not exactly a common occurrence for someone well into their 30s at the time.) It would have been nice if the article had explained what brings that side effect on--and why the hip hop artists don't have huge noggins like Barry. Does it come from heavier dosages? Long-term use? Does it vary from user to user? When they ignore one of the best-publicized side effects it makes you wonder if they truly have a firm handle on the situation.

Marcus61 -- Great title!

I have a hard time believing that HGH is great for "bare-chested stage acts", as the author suggests, but that 50 Cent (in the linked picture) can't bench more than I can, because of his HGH-created "lean body tissue" -- well, and his time in the prison gym.

The fact is, baseball players among others haven't been doubling up on the two drugs for their endorsement poses. Just like Arnold Schwarzenegger, they thought that HGH would indeed enhance their performance, whether via added muscle mass or speedier recovery time.

It's illegal, it's cheating and it's right to group the two together in a sentence. And Sundown is right, if you're going to complain because people lump the two together, then please continue the list of known side-effects. They are far similar than marijuana and heroin -- maybe heroin and crack would have been a better comparison.