Athletes who want to maximise their performance are continually tempted to use illegal drugs to gain competitive advantage and to aid recovery from training and injuries. Recent revelations of widespread doping arising from investigations of the distributionof the anabolic steroid tetrahydrogestrinone by the American company BALCO (Bay Area Laboratory Co-operative) demonstrate the extent of this problem in world class athletes.1

Some commentators have raised concerns that genetic modification or “gene doping” will be the next step in the search for enhanced performance.2 3 4 5 These concerns are based on some impressive studies in genetically modified rodents where manipulation of individual genes has increased muscle mass, muscle strength, or running endurance, depending on the gene that was manipulated. Reviews of these animal studies conclude that such genetic manipulations could also improve human athletic performance.6 7

How likely is it that athletes will use genetic modification? About 10% of athletes have used existing drugs,8 …