THERE is a scene in the hit move Billy Elliott where the young hero just can't stop running. Sprinting through the terraced pit village streets, Billy runs like the wind.

Unlike Billy, Sunderland-born David Reavely finished up with a PE teaching certificate rather than ballet shoes, but he can identify with the fictitious star.

"As soon as I was able to run, I used to escape out of the back garden and just run... they used to have to call the police out to find me," says David, who grew up in the Nookside area of Sunderland.

After the running craze passed - to the relief of his harassed parents - David threw himself into football, swimming and cycling. Then, disaster struck. He reckons he was only nine when he started getting pain in his left knee. He tried to shrug it off but it began to interfere with his ability to kick, run and jump.

"It started in my left knee, usually after a hard game of football or a long run. At the time I didn't think anything of it."

His parents took him to see their GP and a consultation was arranged with a specialist. David remembers hearing the word "arthritis" but had no idea what it meant.

His dad was told young David was "too active" and his left leg had to be immobilised in plaster for six weeks, but rather than being worried, his reaction was typical for his age. "As a young kid I thought it was great, I thought that the plaster cast would be a sort of status symbol, that it would make me the centre of attention at school," he recalls.

The treatment seemed to do the trick for a few years and young David discovered a new sporting passion - weightlifting. "I was only about 13 when I started competitive weight-lifting, I don't think they would let you do it at that age now," says David, who trained at Sunderland YMCA and joined the Sunderland Health and Strength Club, developing an interest in sports nutrition that would soon stand him in good stead.

By the time he was 17, he was doing so well in weight-lifting circles that his name began to crop up in local newspapers. But within two years, with all thoughts of arthritis pushed to the back of the mind, the problem suddenly resurfaced.

"It came back with a vengeance and this time it spread to both knees and then my shoulders," says David, who feared that his sporting life was coming to a sudden and premature end. "I remember thinking 'this can't be happening to me, arthritis is something that old people get'."

Dejected at first, but determined to explore ways of overcoming his health problems, David spent more and more time in the science section at Sunderland Library. The more he read about the workings of the human body and the role of nutrition, the more he became convinced that what you eat can affect your health and well-being.

"I started eating less white bread and white sugar and I stopped eating tinned and packaged food containing preservatives and emulsifiers. I also started making weekly pilgrimages to the local health food shop," says David.

Wholewheat bread, molasses, honey, museli, brown rice and flour made from organically-grown wheat began to replace less healthy food, David found his arthritis wasn't getting any better. "At times I was literally crippled with pain," he remembers.

That's when he made his breakthrough. Following up his research into nutrition, he stumbled across a system called naturopathy, which stresses the importance of a healthy diet and lifestyle.

According to popular television doctor Dr Hilary Jones, naturopathy is based on the belief that the body has the power to heal itself through its own inner vitality. In his excellent guide "Doctor, What's The Alternative: An A-Z of Complementary Therapies", Dr Jones writes that diet is probably the most important aspect of in naturopathy.

"Most naturopathic diets concentrate on wholefoods and vegetarian organic food, which are eaten in their raw state to retain the vitamins and minerals which would otherwise be reduced through cooking."

David began following a strict diet and gradually noticed the difference. "It was quite incredible. All signs of arthritis began to disappear. I felt fitter, looked healthier and I stopped getting colds," says David. He ended up with a diet that was predominantly fruit and vegetables.

David doesn't drink or smoke but does allow himself the occasional luxury - such as goat's cheese.

Since changing his diet, apart from a few minor lapses - when the arthritis symptoms began to return - David has enjoyed a full, active and painfree life. He qualified as a PE teacher in Ponteland, Northumbnerland and worked in Scotland before settling in Kent. These days he acts as a nutritional consultant with a Tonbridge Wells-based company called Signs of Life.

Married to Lorraine, whose family live in the North-East, he has two children, promising tennis player Adam, 14, and daughter Josie, 18, who has illustrated his latest book.

David realises that not everyone could follow his diet but he recommends that everyone should try to eat more healthily, concentrating on fresh fruit and vegetables.

"I have a fairly spartan diet but a lot of people would probably benefit from making less radical changes. The key is that eating more healthily helps to build up the immune system, which helps to protect you from illness, including long-term chronic problems."

David recommends organic soups, organic wholewheat bread, tuna, cod, wholegrain brown rice, organic jacket potatoes, cottage cheese, baked beans, salad and lots of fresh fruit and vegetables. You should drink pure spring, mineral or filtered water to help eliminate toxins and hydrate your system, he says.

David was thrilled when the internationally-known naturopath Jan de Vries, who has appeared on television's Richard and Judy programme, agreed to write a foreword to his new book.

In it, he writes: "I am pleased that Dave, with all his years of research, has shared his knowledge in this book, which can easily be understood and practically applied. I am convinced that this work will show many people some very healthy ways."

The Natural Athlete: How To Maximise Your Performance By Adopting A Natural Lifestyle (£5.99). Copies are available at Ottakar's in Darlington and Sunderland, the Health Warehouse in Darlington or by contacting the author on (01732) 832550.