Testosterone has two main effects on your body: Anabolic effects promote muscle building. Androgenic effects are responsible for male traits, such as facial hair and a deeper voice.

he long-term effects of performance-enhancing drugs haven't been rigorously studied. And short-term benefits are tempered by many risks. Not to mention that doping is prohibited by most sports organizations.

But there's no evidence that creatine enhances performance in aerobic or endurance sports.

Risks

Androstenedione (andro) is a hormone produced by the adrenal glands, ovaries and testes. It's a hormone that's normally converted to testosterone and a form of estrogen (estradiol) in both men and women.

Collins believes that some studies were performed with a conclusion in mind at the outset.

This is false. "We know steroids can be used with a reasonable measure of safety," says Charles Yesalis, a Penn State [Pennsylvania State University] epidemiologist, steroid researcher for more than 25 years, and author of the 1998 book The Steroids Game. "We know this because they're used in medicine all the time, just not to enhance body image or improve athletic performance." Yesalis notes that steroids were first used for medical purposes in the 1930s, some three decades before the current exacting standards of the Food and Drug Administration (FDA) were in place.

Even so, anabolic steroids or their derivatives are commonly used to treat breast cancer and androgen deficiencies and to promote red blood cell production. They are also used in emerging anti-aging therapies and to treat surgical or cancer patients with damaged muscle tissue.

There are more than 600 different types of steroids, but it's testosterone, the male sex hormone, that's most relevant to athletics