January 3, 2007 Nature magazine is reporting a fascinating new discovery by researchers at Harvard Medical School which could help boost human sporting abilities, slow muscle wasting and almost certainly create even more headaches at the World Anti-doping Agency. Led by Bruce Spiegelman, the team of Harvard Medical School scientists hit upon a genetic switch that converts almost all mouse muscle fibres into type IIX. Human muscles are made of four main types of fibre, including two 'slow-twitch' varieties and one 'fast-twitch' muscle type that are suited to endurance and sprint activities respectively. Little has been known about the fourth type, called IIX fibre, because it is scattered throughout different muscles. Spiegelman's team found a specific gene can convert muscles that are a mix of fibre types into mainly slow-twitch fibres and when tested in mice, found the mice were able to run on a treadmill for 25% longer before reaching exhaustion. Sadly, the natural attributes of Joan Benoit Samuelson, Grete Waitz, Derek Clayton, James Peters, Paula Radcliffe, Khalid Khannouchi and Abebe Bikila might be overshadowed by some remarkable performances when this research filters into practical technology for athletes to abuse.