With the Olympic Games just a week away, two new, undetectable drugs have emerged, which could help endurance athletes improve their performance.
Only a couple of weeks ago, Riccardo Ricco, the Italian cyclist, tested positive for a new drug called CERA, a so-called third generation of the banned red blood cell-boosting substance EPO.
CERA had only been approved for clinical use in late 2007 and was only made available to buy in January of this year, but by July ? and possibly earlier ? it was already in the sports world.
Now it is feared two drugs, which have only been tested on mice, could be used by cheating athletes at the Beijing Games.
One drug, AICAR, enabled a mouse that had done no exercise to run 44 per cent longer than a similarly sedentary mouse without the drug.
The other drug, GW1516, allowed trained mice to run for 77 per cent longer, covering 68 per cent more ground than mice without the substance.
According to reports, the World Anti-Doping Agency has been working on a test to detect the use of the two substances, but that it is unlikely to be ready in time for the Olympics.
However, it is unknown what benefit ? if any ? the drug has on humans. But lead researcher Ronald Evans of the Salk Institute for Biological Studies in La Jolla, California, told the Los Angeles Times he had already been approached by athletes interested in AICAR.
Evans is the professor who, in 2004, created the so-called ?marathon mouse? or ?Armstrong mouse? by injecting a single gene into a fertilized egg to create mice that had more efficient muscles, quicker metabolisms and stronger hearts.