Athletics: Can turtle's blood make you a champion?: Gail Vines searches for the mystery ingredient that makes Ma Junren's female athletes the fastest in the world

THE WOMEN'S race in the IAAF's biennial World Marathon Cup is not usually considered one of the highlights of the athletics calendar. This year's event, however, which takes place in San Sebastian in Spain next Sunday, is expected to attract an unprecedented degree of attention. Not only will the year's two most controversial world record breakers, the Chinese athletes Wang Junxia and Qu Yunxia, be competing, but their equally controversial coach, Ma Junren, will be there too.

The success of Ma Junren's runners - who recently broke world records in the 1,500, 3,000 and 10,000 metres by astonishing margins - has inspired dark mutterings about drug abuse among his charges. Ma Junren denies foul play, and insists that it is simply good food and hard work that have enabled his runners to extend the frontiers of athletic achievement so dramatically. Intriguingly, many of Britain's leading sports scientists seem to agree.

Ma puts his athletes through a gruelling regime. Day after day, the women run the equivalent of a marathon and then lunch on turtle soup washed down with turtle's blood. 'The turtles are very nutritious,' he claims. Such explanations 'won't wash in the West', snarls one sports commentator, John Rodda, who is convinced that no woman could train as hard or race as fast as the Chinese do without using anabolic steroids. Yet British sports scientists are more hesitant about putting the Chinese success story down to pharmaceutical mischief.

Most agree that diet is likely to be important, although none sets much store by tipples of turtle's blood. The blood of these reptiles, like that of any other back-boned animal, is rich in iron and contains a variety of proteins such as albumin, the protein of egg-whites. But eating steak and eggs would give you a similar complement of nutrients. 'I don't believe the Chinese have any magic potion that could make that much difference in performance,' says Eric Newsholme, of Oxford University, one of Britain's leading exercise biochemists and a seasoned marathon runner as well. But Newsholme does suspect that the local staple diet of rice and vegetables might provide part of the explanation. 'A high- carbohydrate diet from the word go might be ideal for distance running,' he says. Eating four-fifths of your calories as complex sugars and starches from childhood might boost the muscles' ability to store glycogen, a vital source of energy.

David Collins, sports psychologist at Manchester Metropolitan University, suggests a psychological explanation: specifically 'the very large carrots' on offer. Even if drugs are part of Ma's regime, he argues, the secure lifestyle and comprehensive support that the athletes enjoy is probably a more crucial ingredient.

'Cultural differences' are singled out by Phil Jakeman, a biochemist in the sports science department at Birmingham University. Coaches can select the youngsters with the greatest potential, discard the ones that don't make the top ranks and then work the rest very hard for years on end. The result is 'planned optimalisation' of the nation's athletic potential.

Like Jakeman, Sharp points out that Chinese coaches have a 'gigantic' number of women to choose from - a fifth of the world's female population - most of whom will be accustomed to hard physical labour. What's more, many of Ma's athletes grew up in China's highlands, living at 6,000 feet or more, and so have blood adapted to carrying more oxygen than that of lowlanders.

Finally, Sharp says, the Chinese coaches are following good coaching regimes. Ma's training scheme builds aerobic stamina with very high mileages at relatively low speeds. He then switches his runners to months of speed work. The result is runners who can sustain a fast aerobic pace but can also spring very fast in the crucial last few metres of a middle-distance race. This mixed regime is especially good for the muscle fibres known as the IIB or glycolytic fast fibres. These are primarily devoted to short-term power and speed, but endurance can be built into them too.

Sharp's most telling observation, however, is that the Chinese have attacked the 'softer' records. Women on average run between 90 and 93 per cent of men's speed at any event, from the 100m to the marathon, he claims. But until recently this otherwise straight line sagged a bit at 1,500m and 5,000m, and especially at 10,000m.

'The Chinese may be to women what the Africans were to men,' Sharp says, 'the thin edge of a wedge that is going to drive very deep. There is probably nothing sinister about it; it was almost inevitable.'

So is there nothing special in turtle's blood after all? The openminded Sharp is reluctant to be dogmatic. 'Maybe by accident the Chinese are taking some micronutrients that are right,' he speculates. 'But I think probably not.'