Creatine monohydrate is a compound produced by your body that helps release energy in your muscles. Creatine is a naturally occurring compound — you can ingest creatine from protein-rich foods such as meat or fish, or you can take a nutritional supplement. Supplements are available over the counter.

Unlike androstenedione, scientific research indicates that creatine may have some benefit — it can produce small gains in short-term bursts of power.

"Most of the research points to small improvements in short-term power activities like improving maximum-weight bench press or increasing speed during cycling sprints of very short duration," says Edward Laskowski, M.D., a physical medicine and rehabilitation specialist at Mayo Clinic, Rochester, Minn., and co-director of Mayo Clinic's Sports Medicine Center. "Some studies have shown an increase in lean muscle mass with creatine. As a result, we've got a lot of press on creatine producing steroid-like results without the side effects."

Creatine helps muscles make and circulate more adenosine triphosphate (ATP). ATP is used for quick, explosive bursts of activity, as in weightlifting or sprinting. Creatine also reduces energy waste products — such as lactic acid — that can cause muscle fatigue. As a result, creatine is purported to enhance performance and decrease fatigue. But there's no evidence that creatine enhances performance in aerobic or endurance sports.

Your liver produces about 2 grams of creatine each day. You can also get creatine from the meat in your diet. Creatine is stored in your muscles, and levels are relatively easily maintained. Because your kidneys remove excess creatine, the value of supplements to someone who already has a high muscle creatine content is questionable.

Possible side effects of creatine that can decrease athletic performance include:

Stomach cramps

Muscle cramps

Nausea

Vomiting

Diarrhea

Weight gain is a known side effect of creatine — one that is sought after by athletes who need to increase their size. But with prolonged creatine use, weight gain is more likely the result of water retention than an increase in muscle tissue. Water is drawn into your muscle tissue, away from other parts of your body. This puts you at risk of dehydration.

High-dose creatine use may potentially damage your:

Kidneys

Liver

Heart

It's unknown what kind of effect taking creatine has over the long term, especially on teens or younger children. Dosage levels vary widely, depending on which product you use and how much creatine you take.

Since creatine isn't regulated by the Food and Drug Administration (FDA), you can't be sure of the purity of creatine supplements you buy on the market. Studies have found varying mixtures of creatine in different creatine products. And some of the inactive ingredients mixed in with the creatine may cause significant side effects, such as allergic reactions.

The bottom line is that the safety of taking creatine is questionable. Most studies involving creatine use examine the performance-enhancing aspects, and side effects are generally reported only anecdotally.

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

Manufacturers of synthetic androstenedione, through vigorous marketing efforts, have claimed that their products increase your body's production of testosterone. According to proponents of andro supplements, an elevated level of testosterone allows athletes to train harder and recover more quickly.

Scientific studies that refute these claims are now emerging. In fact, these studies show that supplemental androstenedione doesn't increase testosterone and that your muscles don't get stronger with andro use.

On Oct. 22, 2004, the Anabolic Steroid Control Act of 2004 classified andro as a controlled substance, adding it to the list of banned anabolic steroids and making its use as a performance-enhancing drug illegal.

Side effects of andro differ for men and women. In men it can actually decrease the production of testosterone while increasing the production of estrogen. Side effects in men include acne, diminished sperm production, shrinking of the testicles and enlargement of the breasts. In women, side effects include acne and masculinization, such as deepening of the voice and male-pattern baldness. Andro might also stunt your child's growth.

In men and women, supplemental androstenedione can decrease high-density lipoprotein (HDL) cholesterol (the "good" cholesterol). Lower HDL levels put you at greater risk of heart attack and stroke.

Some athletes take a form of steroids — known as anabolic steroids — to increase their muscle mass and strength. The main anabolic steroid hormone produced by your body is testosterone.

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.

The anabolic steroids that athletes use are synthetic modifications of testosterone. These drugs were developed in an attempt to maximize the anabolic effects and minimize the androgenic effects of testosterone. As it turns out, these two actions of testosterone can't be separated.

Given by pill, injection or topical treatment, these hormones have many medical uses. Some of these include replacement therapy for men deficient in testosterone, helping people with AIDS maintain muscle mass and reduce muscle wasting, and treating rare types of anemia.

Why are these drugs so appealing to athletes? Besides making muscles bigger, anabolic steroids may help athletes recover from a hard workout more quickly by reducing the amount of muscle damage that occurs during the session. In addition, some athletes may like the aggressive feelings they get when they take the drugs.

However, many athletes take anabolic steroids at doses that are much higher than those prescribed for medical reasons. The effects of taking anabolic steroids at very high doses haven't been well studied.

Anabolic steroids come with serious side effects.

Men may develop:

- Prominent breasts

- Baldness

- Shrunken testicles

- A higher voice

- Infertility

Women may develop:

- A deeper voice

- An enlarged clitoris

- Increased body hair

- Baldness

- Increased appetite

Both men and women might experience:

- Severe acne

- Liver abnormalities and tumors

- Increased low-density lipoprotein (LDL) cholesterol (the "bad" cholesterol)

- Decreased high-density lipoprotein (HDL) cholesterol (the "good" cholesterol)

- Aggressive behaviors, rage or violence

- Psychiatric disorders, such as depression

- Drug dependence

If an injected form is used, you'll face a higher risk of infections and diseases that are transmitted in blood, such as HIV and hepatitis. And in teens, steroids can halt their normal pattern of growth and development and put them at risk of future health problems.

Anabolic steroids aren't legal substances, unless your doctor has prescribed them for medical reasons. Taking anabolic steroids to enhance athletic performance, besides being prohibited by most sports organizations, is illegal.

One anabolic steroid receivng a lot of attention is tetrahydrogestrinone (THG). Until recently, THG was marketed as a dietary supplement for enhancing athletic performance. However, researchers have found that THG is actually a chemically altered version of an anabolic steroid that is banned by most sports organizations. THG is referred to as a "designer" steroid because it's undetectable by traditional steroid testing techniques. A new laboratory test, however, now makes its detection possible. The Food and Drug Administration (FDA) warns that athletes taking THG may be putting their health at risk — THG is an unapproved new drug and little is known about its safety.

Other common anabolic steroids include dehydrochlormethyltestosterone (Turinabol), metandienone (Dianabol), methyltestosterone (Android), nandrolone (Durabolin), oxandrolone (Oxandrin), oxymetholone (Anadrol) and stanozolol (Winstrol).