Pilates: the good, the bad - and the beautiful

Madonna does it. So do Demi Moore, Elizabeth Hurley and Sigourney Weaver. Even Hugh Grant's known to indulge. Along with the beautiful people, an estimated one million people in the UK practise Pilates, a form of exercise also known as body control. Its fans say regular classes result in a sleek and streamlined physique while improving overall fitness and flexibility.

Devised in the early 20th century by a German-born nurse, Joseph Pilates used his system to rehabilitate First World War soldiers who had difficulty walking by helping them build up enough arm and abdominal strength so that they could stand.

Focusing on the "core" of the body, Pilates works on strengthening the deep torso muscles. Drawing in your navel to your spine is supposed to engage a deep abdominal muscle called the transverse abdominus. The theory is that if you pull in this muscle often enough, it will eventually work on its own, improving posture and balance, while protecting the lower back.

Although doctors and physiotherapists often recommend Pilates as one of the safest forms of exercises, including for those patients with back and neck problems, some experts have criticised the programme.

Stuart McGill, a professor of spine biomechanics at the University of Waterloo in Canada, who has treated patients with back disorders for 25 years, said that strengthening the "core" muscle often worsens back pain. "If you hollow in, you bring the muscles closer to the spine, and you reduce the stability of the spine," said Dr McGill. "Try rising from a chair with a hollowed-out stomach. Not only are you weak, it is very difficult."

According to the charity BackCare, almost half of all UK adults suffer from back problems. But when they conducted an internet survey, Pilates emerged as the most effective long-term approach for back pain.

"Pilates, yoga and other exercise programmes can all be part of the 'staying active' regime," says Dr Dries Hettinga of BackCare. "It goes without saying though that adequate instruction by a qualified instructor is essential if the programmes are to be safe and effective."

Dr Hettinga says that if you experience worsening back pain as a result of a certain exercise, you are advised to contact your GP and perhaps try a different exercise programme. "For back pain there is no one-size-fits-all approach."

Watch physiotherapist Caroline Blackburn's tips on Perfecting your posture.

Look at Dr David Bull's video guide on How to avoid back pain in the workplace.

Learn more about Pilates including how to select a teacher and find a class from the Pilates Foundation.