Of course, there is also an illegitimate way: concealing the use of performance-enhancing drugs. The sporting world is strewn with careers that have been shattered and reputations wrecked through the detection of banned substances in the blood and urine of some of these prized athletes. Offenses include cyclists injecting erythropoietin to create an overabundant supply of red blood cells, baseball players using anabolic steroids to stimulate muscle growth and enhance strength, sprinters inhaling beta 2 agonists in doses far exceeding the range used for treating asthma to get an extra jump in their stride and archers using beta blockers to steady their hands and calm their nerves.6 With the recent revelation that tennis star Maria Sharapova failed a urine toxicology test, we learned about meldonium, a heretofore unheard of drug in Western countries that gained popularity in the Soviet Union as a compound that purportedly enhanced the stamina of Soviet army recruits drafted to fight in the high-altitude mountain ranges of Afghanistan.7
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Explore This IssueMay 2016
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Even one of our favorite drugs, probenecid, is on the World Anti-Doping Agency (WADA) watch list, because it has been used in nefarious ways to mask the presence of other banned substances.
There may also be a third way to gain that competitive edge—one that isn’t illegal but still raises some serious questions. In these cases, the athlete seeks the advice and the prescribing powers of physicians who foster controversial approaches to managing selected complaints. This may take the form of injecting platelet-rich plasma or stem cells into aching joints and injured tendons in an effort to get them to heal more quickly. Or it may have arisen when an athlete, such as nine-time Olympic medalist Carl Lewis, felt lethargic as he struggled to earn a berth on the 1996 U.S. Olympic Team. After consulting with an endocrinologist who steadfastly believed that young, elite athletes are prone to developing hypothyroidism, even with normal levels of thyroid-stimulating hormone (TSH less than 2 units), Mr. Lewis began taking levothyroxine and immediately felt well enough to go on to win the gold medal in the long jump.8 Can one truly be hypothyroid with a normal level of TSH? Is this observation a scientific breakthrough or pseudoscience?
This same physician, who serves as a consultant to Nike, has also diagnosed five of the 30 members of its elite distance running team with hypothyroidism. That is an interesting statistic because hypothyroidism is highly uncommon in healthy young people. According to WADA, thyroid hormone use is not banned, because in their view, no evidence proves that it enhances performance. However, they seem to contradict themselves by banning human growth hormone use even though it, too, lacks data showing that it enhances athletic ability.
Gene Doping: The Next Frontier?
The transforming growth factor-beta superfamily includes a large group of growth and differentiation factors that play critical roles in regulating embryonic development and maintaining tissue homeostasis in adult animals. In 1997, researchers at Johns Hopkins University in Baltimore identified a new family member, myostatin, that is mainly expressed in skeletal muscle, which is also its primary target.9 Interestingly, the myostatin gene is a negative regulator of muscle growth and regeneration, and silencing it creates rodents with sizable muscle hypertrophy known affectionately as Schwarzenegger mice. This observation has caught the attention of WADA, which has expressed concern that its next challenge may be dealing with gene doping by athletes hoping to unleash muscle growth by inserting genes or their products into their muscles.