Why Athletes Use Clenbuterol for Performance

Alberto Contador of Spain and Team Saxo-Tinkoff reacts as he crosses the finish line at the end of stage eighteen of the 2013 Tour de France, a 172.5KM road stage from Gap to l'Alpe d'Huez, on July 18, 2013 in Alpe d'Huez, France.
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Clenbuterol, also called "clen," is considered a performance-enhancing drug. It's banned from most athletic competitions. Both the World Anti-Doping Agency and the International Olympic Committee include clenbuterol on their lists of prohibited drugs. Even so, athletes continue using clenbuterol for its ability to help burn fat, build muscle, and improve performance. This is unfortunate because clenbuterol has been linked to a number of serious side effects.

Not Meant for Human Consumption

Clenbuterol is a type of medication that's a selective beta-2 agonist/antagonist and bronchodilator, which means it relaxes the smooth muscle tissue that makes up the airways to allow for freer breathing. The United States Food and Drug Administration has approved clenbuterol only for use by veterinarians, who may prescribe it to treat horses with obstructive pulmonary disease or other lung conditions. The trade name for clenbuterol used for horses is Ventipulmin.

The "human equivalent" of clenbuterol is albuterol, which is a prescription-only medication used to treat or prevent bronchospasm caused asthma, bronchitis, emphysema, and other lung diseases, and also to prevent wheezing caused by exercise.

There are a variety of brand names for albuterol, including Ventolin, Proventil, Accuneb, among others. Regardless of whether it comes in generic or brand name form, albuterol comes in an inhaler that a person can use to breathe the medication in through the mouth so it can easily reach the airways.

In the past, clenbuterol was given to livestock to increase to increase lean muscle mass and the overall yield of livestock production. Now it's banned from being used for this purpose in the U.S. and much of Europe. Even so, athletes who test positive for clenbuterol often claim they must have eaten contaminated meat. Three-time Tour de France winner Alberto Contador may be the most famous athlete to have used this excuse after testing positive for clenbuterol.

Athletes who use clenbuterol do it to burn fat, build muscle, and improve sports performance. The drug is believed to increase the development of skeletal muscle by enhancing muscle protein synthesis. At the same time, it aids in fat loss by increasing metabolism.

In general, any positive effects of taking clenbuterol seem to be temporary and short-lived.

Dangers of Taking Clenbuterol

The effects of clenbuterol on athletes who take the drug over a long period of time aren't known. What is clear is that besides affecting the muscles of the airways, clenbuterol is taken up by other tissues in the body. Animal studies have shown that clenbuterol use may lead to apoptosis—the death of normal cells—in the muscles, including the heart muscles. For this reason, veterinarians are cautioned against giving the drug to horses who have cardiac issues.

Clenbuterol may cause cardiac hypertrophy (enlargement of heart ventricles), a potentially serious form of heart damage, as well as irregular, heart rhythms. Other side effects of clenbuterol use include muscle tremors, increased perspiration, increased blood pressure, insomnia, headache, nausea, and vomiting. An athlete who chooses to rely on a banned performance-enhancing drug rather than hard work and practice not only is risking being caught for cheating. He also may be risking his health.

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