In any city park in China at dawn thousands of people can be seen doing fan-dancing, kick-boxing, quick-steps, taichee and other forms of exercise, including the oldest of all, qigong.

Those doing qigong make slow deliberate movements, stand quite still or commune with trees. It is a unique Chinese sport.

But there is also medical qigong, an ancient therapy applied by expert practitioners to help control the energy of a body which is out of alignment.

Medical qigong has one practitioner in Ireland, Noeleen Slattery, who runs a clinic of traditional Chinese medicine in Rathcoole and Rathmines in Dublin.

Ms Slattery, a former nurse whose personality seems to combine an aura of tranquillity with utter determination, became interested in Chinese medicine in the early 1980s through Dr James Clarke, a specialist in a nursing home she then ran in the writer Christy Brown's old house and art gallery in Rathcoole. She saw how he detoxified patients through acupuncture, which releases the toxic heat, and achieved dramatic results.

She first travelled to China to find out more in 1988. "Everyone thought I was mad, including my own children," she said. But Ms Slattery qualified as a doctor of traditional Chinese medicine at a university in Nanjing that year, and vowed one day to return to study medical qigong under a master. The opportunity came in October, when she signed up for a course at the Beijing College of Acupuncture and Orthopaedics under a much-respected expert in traditional chinese medicine, Prof Hu Xiao.

Before returning from Beijing on November 10th she explained what drove her to make her own way to China and endure the deprivations of a student hostel at a Chinese medical college.

"I wanted this for my patients to help them have a better quality of life, for example in the case of serious illnesses to prolong their lives with quality," she said.

She has used qigong, sometimes combined with tuinaa, the art of massaging to bring the body into alignment, for the past 10 years. "Mostly I trained myself to do it but I wanted to perfect it, though when I came here I discovered that 90 per cent of it was right." The theory of medical qigong is based on knowledge of the internal energy called the qi, or life force.

"This is what drives you, what keeps your blood flowing, what keeps your organs in good health, your vision good and your hearing good. When something goes wrong with the qi of your body there will be stagnation. You won't have a free flow. Illness will develop eventually in some place or other. You will get pain. "First of all I will do a diagnosis. I will tell you how I think your body is. You get very observant. When somebody walks in the door I know straight away what their colour is, the whites of their eyes, how they breathe, how they hold their body. Sometimes I can tell people they have pain which they haven't told me about."

A session begins with about 20 minutes of total quietness. "I can sit with my eyes closed and sense how your breathing changes and I will then move your qi with mine. I will guide it. It's all about sensitivity. I must have a total stillness. I will start moving it with my hand, by literally scanning your body without touching it. It's like a magnetic field." If successful, medical qigong will move out waste and stagnant energy "like cleaning the silt from a stagnant canal."

Many general practitioners refer patients to her, she said. Some with chronic illnesses will come once every six to eight weeks, others just once a year. Patients can learn from her how to practise qigong on their own.

"It's like sitting down and going to sleep or into a dream, but you are actually fully alert and you're sensing what's happening inside in your body," she said. "You can go into a state of qigong anywhere and hear nothing around you. You are totally alert, but you can switch off and take yourself into nice quiet calmness."

Her recommendation to her patients is to practise qigong for half an hour every day. But it can be done at home, she said. You don't have to go to a Chinese park at six in the morning.