The anabolic steroid claimed its most glamorous star even before the start of the World Athletics Championships, ending Jamaica Merlene Ottey's record run of medals and denting her golden career.

Nandrolone already has cut short the career of 1998 Australian Open tennis champion Petr Korda, and forced Pan American Games officials to strip two Cubans of their weightlifting gold medals.

Explaining the sudden rash of Nandrolone cases leaves many stumped.

``I have absolutely no idea. I would be very grateful if someone could give an explanation,'' said Istvan Gyulai, secretary general of the IAAF, athletics' world governing body.

With yet another Nandrolone scandal overshadowing the sport, Gyulai was trying to put a positive spin on the situation. ``Maybe it is showing that the control system is also becoming more efficient,'' he said.

World soccer's medical chief, MichelD'Hooghe, agreed. ``Maybe it is also showing that the control system is becoming more efficient,'' he said. This spring, France's World Cup star, Christophe Dugarry, tested positive for Nandrolone.

And even though most concede new, sophisticated equipment is partly responsible for the breakthrough, IAAF drug chief Dr Arne Ljungqvist is considering other options.

Ottey is 39, the same age as 1992 Olympic champion Linford Christie, athletics' other high-profile athlete who tested positive for Nandrolone during a winter meet.

``It is a fact that many of those athletes who have been found recently are on the verge of retiring or retiring age. You could possibly think that they are more inclined to use food supplements to extend their career an extra few years,'' Ljungqvist said.

He said such supplements might lack sufficient controls and might contain the precursors or the illegal substance.

Considering the current crop of high-tech drugs, many are surprised top athletes would still want to useNandrolone, which has been around since the 1970s and has been detectable.

``It is one of the drugs of choice these days,'' said D'Hooghe, also still groping for a full explanation.

Ljungqvist said many of the athletes caught recently also would have tested positive with equipment available in the past. Nandrolone boosts bulk, muscle growth and physical strength, key ingredients in the athletes' performance.

The body itself produces a limited amount of Nandrolone but levels found in athletes testing positive for the drug go far beyond that. Some claim contaminated food might explain high levels.

In Britain, research into the drug is increasing following the case of Christie and the positive test of 1998 European 200-metre champion Doug Walker of Britain.

Walker was cleared by his federation, which said he used the banned substance in an ``innocent and accidental'' manner. The IAAF is sending the case to an independent arbitration panel.