HOLLYWOOD, Fla. (WSVN) — New York Yankees player Alex Rodriguez's recent suspension has re-ignited debate about performance-enhancing drugs. What are they, and can they really build a better athlete?

Doctors say there are several different types of PEDs. The most commonly abused are anabolic steroids and even designer drugs like Pre-Pro, THG or The Clear, which are created to be undetectable in drug tests.

"Anabolic steroids are agents that mimic the action of our own testosterone," said Dr. Paul Jellinger, an endocrinologist at Memorial Regional Hospital. "What testosterone does is, it attaches to androgen receptors within our cells and it builds muscle and subsequently builds strength."

Dr. David Westerdahl, who practices sports medicine at Cleveland Clinic, said PEDs can give baseball players like Rodriguez a physical edge over their peers. "If you are in a sport that benefits from additional muscle mass, additional speed, additional ability to recover faster, then anabolic steroid does confer a competitive advantage," he said.

Westerdahl added, however, that PEDs take their toll on male users' health. "Anabolic steroids for men can increase muscle mass, but they also shut down your own testosterone production," he said. "That can result in male pattern baldness, as well as infertility and impotence. Long-term effects, we're more concerned about from a cardiovascular standpoint."

High profile athletes have also been linked to injecting themselves with human growth hormone or HGH. "If one gives extra growth hormone when there is not a deficiency, you reduce the amount of muscle fat and increase the lean body mass, so you get muscular," said Jellinger.

While users may get lean, doctors have said, there is no definitive proof HGH actually boosts athletic performance. In addition, they worry HGH abusers could increase their chances of developing cancer. "Since it's a growth factor, can long-term exposure to growth hormone actually predispose to cancerous growth? I think there is concern that may happen over a long-term basis," said Jellinger.

For professional athletes, even stimulants and popping supplements found at health food stores can be considered PEDs. "You'll see athletes, from time to time, who may have failed a drug test, who say, 'I didn't know that was in the supplement,'" said Westerdahl. "Athletes at all levels are responsible for what they put in their body."

Rodriguez, who plans to appeal his suspension, joins a long list of Major League Baseball stars accused of using the controversial substances. Past high-profile players caught up in doping scandals have also included Milwaukee Brewers slugger Ryan Braun as well as Roger Clemens, Barry Bonds and Mark McGwire.

Experts say PEDs can be ordered off the Internet. In addition, some labs make and sell them, and some drugs are even stolen from animal clinics.

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