Legal Performance-Enhancing Drugs

Scandals in professional cycling and Major League Baseball's attempts to start clamping down on steroid use has brought greater attention to the world of performance-enhancing drugs. While many PEDs are illegal and can cause devastating effects on the human body, many performance enhancers are still on the market and widely used in sports and by bodybuilders.

Creatine

• Communist Eastern-bloc countries were the first to develop creatine, and the substance started gaining popularity in the West after the fall of the Berlin Wall. Companies quickly marketed the product in the United States as an energy-enhancing supplement that would fuel muscle growth. Creatine is a synthesized blend of amino acids, the building blocks of protein, and it provides quick bursts of energy, allowing athletes to work harder. Although no studies demonstrate that creatine is dangerous, scientists don't know much about its long-term effects.

Androstenedione

• Androstenedione is a precursor to testosterone, and it helps boost the growth of muscle tissue by raising testosterone levels in the body. Companies that market "andro" say that it provides some of the benefits of illegal anabolic steroids without the nasty side effects such as hair loss, acne and impotence. The drug gained notoriety in the late 1990s with the revelation that baseball player Mark McGwire used it before hitting a record 70 home runs in 1998. Some stores refuse to sell it out of safety concerns, but other stores and gyms do sell it.

B12

• Vitamin B12 is an energy booster that comes in many forms, and B12 injections have become popular among athletes who want a boost of energy. B12 allows red blood cells to carry oxygen in a more efficient manner. B12 is found naturally in foods like meat and eggs, but B12 shots deliver the vitamin at a much higher concentration and all at once. Shots of B12 in reasonable doses are not dangerous, although you might experience side effects such as headaches and nausea.

Caffeine

• Many Americans drink lots of caffeine every day in the form of soft drinks and coffee, but some athletes use it to gain an energy boost to help their performance in races and sporting events. Caffeine helps boost muscles by releasing calcium in the muscle, increasing athletes' endurance while reducing the sensation of exhaustion. Athletes might need as little as a single cup of coffee to boost their performance if they go without it for a while to increase the stimulant effect.