South Africa's golden girl Penny Heyns has disclosed the secrets behind the winning streak that saw her slashing her seventh world record in Sydney on Friday.

They are: (1) her creator and (2) her Creatine.

A Christian, she attributes her success to God. She also takes a food supplement which has given her bigger muscles.

After her record-breaking blitz this week, Heyns revealed she had used the controversial food supplement to give her career a boost. It worked.

Her latest coup was in the 200m breaststroke final in a time of 2:23.64 at Friday's Pan Pacific championships.

Creatine, sold as a legal alternative to anabolic steroids, is widely used in professional sports such as baseball, soccer and America's National Football League (NFL), while French tennis player Mary Pierce has credited the supplement for her increased muscle bulk.

Heyns said she reached the stage where she hated her sport, but after deciding to carry on to next year's Sydney Olympics, she wanted to do everything possible to make sure she competed at her best.

"I'd be swimming pretty well whether I was on it or not," Heyns said of Creatine. "But I have the attitude that I don't want to get on the blocks during my career and know that I've trained and swum as hard as I could, but that there was a nutritional side that I didn't do the best I could in. I want to cover all the bases."

Creatine is a protein which is produced naturally in the liver and kidneys. But over-use has been linked to problems such as cramping and dehydration.

"I think if you take a big dose it makes you feel sick," Heyns said. "I take a very low dose. I think with a lot of the swimmers, it varies with how much they take, as far as being sick. They take too much."

Two NFL clubs, Tampa Bay and Cincinnati, have banned their players from taking Creatine, while several national Olympic committees have asked the International Olympic Committee (IOC) to add it to its banned list.

The IOC's medical commission, headed by Prince Alexandre de Merode, cleared Creatine last year, saying it was a food. He added that while it helped to build muscles, it should not be lumped with testosterone or anabolic steroids.

Pierce is the most publicised recent case of a professional athlete using Creatine. Her increased strength and muscle mass was the centre of attention during this year's Wimbledon championships.

"I'm not a scientific person. I don't know all about it, but it really helps recovery," Pierce said. "It helps you when you lift weights, run hard. It helps to rebuild the muscle tissue and the fibres you tear a little bit."

Creatine supplements work by helping the body to replenish adenosine triphosphate, known as ATP, which is a key source of energy.

Cape Town's Sports Science Institute's biokineticist, Mr Justin Durandt, said the supplement would not make a champion out of you and was not a wonder drug. He said there was no correlation between Creatine and swimming performance. Durandt said Creatine helped only those who needed extra strength.

"Its main effect is to increase muscle size," he said. "In certain individuals, it may allow them to train harder."

When Heyns broke her seventh world record on Friday, her mother, Patsy, could sense the event.

Speaking from her Amanzimtoti home minutes after her daughter broke the record, she said: "I just knew she was swimming now. I could just feel it."

Mrs Heyns said she was immensely proud of Penny's achievements.

Heyns practically learnt how to swim before she could walk. At 11, she started training heavily, swimming both before and after school.

Contrary to recent reports, Mrs Heyns did not think her daughter was on the verge of retirement.

"If she feels that the Lord wants her to continue after the Sydney Olympics, she will," she said.

Her mother knew she was taking the supplement and said Penny's muscles had got noticeably bigger.

A number of South Africa's rugby, hockey and cricket players take Creatine. Used as part of an intensive gym programme, it results in increased muscle and body mass.

However, Dr Ludwig Bohmer, a local private school doctor, has warned against the use of Creatine for school-going sports players as it has been known to increase muscular injuries in young developing bodies.