Nandrolone is an anabolic steroid which acts in a similar way to the hormone testosterone, increasing muscle size, aiding recovery and allowing harder and longer training. Its potential side-effects include kidney damage, impotence, heart and liver disease and dramatic mood swings, known as "roid rage."
Nandrolone is not a "designer steroid" - it is well known, and easy to discover. The only mystery is why sportsmen and women continue to test positive for it, although one obvious reason may be a scientifically proven incidence of the substance turning up in nutritional supplements which should not contain it.
In 1999 the International Olympic Committee laboratory in Cologne run by Professor Wilhelm Schaencer began a two-year study of nutritional supplements and discovered that a significant proportion - 16 from the first 100 investigated - had been contaminated during production with pro-hormones which the body metabolises to produce nandrolone.
The investigation was prompted by a glut of nandrolone positives in athletics involving names such as Linford Christie, Merlene Ottey, Doug Walker and Mark Richardson. In February 2001, Schaencer confirmed that contaminated supplements had caused volunteers to return urine samples well above the legal limit of two nanograms per millilitre, with the highest recorded being 600 nanograms per millilitre.
Nandrolone won a high profile in 1990 when the then world 400 metres record holder, Butch Reynolds, tested positive and received a two-year ban despite pleading innocence. Eight years later the Czech tennis player Petr Korda tested positive for nandrolone and received a ban, although he was later acquitted. In 2003 seven tennis players were cleared by the Association of Tennis Professionals, which admitted it may have given players contaminated supplements.
Also in 2003, Greg Rusedski was cleared of a positive test for nandrolone using the same line of defence. In the world of doping, it seems, nothing is simple.