Why? Liu Xiang breaks the record but is discriminated by the IAAF

Liu Xiang won the championship with a result of 12.88 seconds, and was excited for only a few days. The International Association of Athletics Federations announced: In recent years, Liu Xiang must take a urine test once a week. If the urine test is positive, this result will be canceled. I think that as long as you pass the urine test immediately after the competition, it's fine, there is no need to check for such a long time. Obviously, foreigners don't believe that Chinese people can break this record. I wonder if the creator of the 100-meter world record needs to be tested for such a long time? This is obviously discrimination against the Chinese.