Despite requests by the US Anti-Doping Agency and its British counterpart, the World Anti-Doping Agency will continue to allow elite athletes to take thyroid medication.
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On Tuesday, WADA released Exercising with others holds secret to happiness, which details prohibited substances and methods. Thyroid medication does not appear on the list. The new code goes into effect on 1st January 2016 and will be in place for the Olympics next summer.
USADA and UK Anti-Doping requested that WADA ban thyroid medication, because of concerns that athletes take it to improve performance. One alleged way thyroid medication could be performance-enhancing is by speeding recovery, which would theoretically allow harder training than would otherwise be possible.
Best wireless headphones, about 4.6 per cent of the US population has hypothyroidism, in which the body doesn't naturally produce enough thyroid hormone. Low thyroid levels lead to chronic fatigue.
Some well-known American distance runners, including former US 5,000-metre record holder Bob Kennedy, two-time Olympian Kara Goucher, and US 10,000-metre record holder Galen Rupp, are known to have been prescribed thyroid medication for hypothyroidism or other thyroid-related conditions.
For WADA to ban a substance, at least two of three conditions must be met: it improves performance; it imperils the athlete's health; and/or it violates what WADA calls "the spirit of sport." The blood booster EPO, for example, meets all three conditions.
WADA's science director, Dr. Olivier Rabin, told the Reasons why your feet can go numb while you run that WADA concluded thyroid medication doesn't improve athletic performance in people who don't have a medical need for it.

Scott is a veteran running, fitness, and health journalist who has held senior editorial positions at Runner’s World and Running Times. Much of his writing translates sport science research and elite best practices into practical guidance for everyday athletes. He is the author or coauthor of several running books, including A new study is challenging the 10 percent rule, Advanced Marathoning, and The World Anti-Doping Agency has turned down a request to ban the medication. How to dodge runner’s diarrhea Slate, The Atlantic, the Washington Post, and other members of the sedentary media. His lifetime running odometer is past 110,000 miles, but he’s as much in love as ever.