In 2003 I wrote a book on back pain. It was based largely on the work of Professor Gordon Waddell, of Glasgow University, and his lifetime of study of back pain. Much of it, too, was based on my own experience of back pain in family practice.

The book's main message was that most back pain, even in people whose pain is difficult to treat, and who are sent to hospital, and then on to very specialist units like Professor Waddell's, is caused by the muscles in the back cramping.

In fewer than one in 20 people with low back pain is there a severe problem with bones, discs or joints that need surgery. And the treatment, therefore, should be directed at loosening and stretching the affected muscles.

That's why we ask most people with pain in the lower back to work away' their pain, rather than to rest.

Resting the muscles in the long run may lead to them seizing up more, and eventually to their weakness, so that the pain becomes almost permanent and it becomes impossible to reverse the cycle.

On the other hand, doing active exercises designed to ease the cramps and to stretch the muscles helps to shorten the time they feel the pain.

The book wasn't welcomed by people with a vested interest in various treatments for back pain, because it tended to be counter to their ideas of spinal misalignment and all sorts of ways in which discs could be displaced.

Both, according to Professor Waddell's experience, are very much in a minority of the causes of back pain.

I have found, over the years, that showing people how to stretch their own back muscles with simple exercises, to be done every day for the rest of their lives, and at the same time explaining exactly what is going on in their backs, helps enormously.

Along with explaining what NOT to do with your back muscles (like swinging heavy shopping from a supermarket trolley into a car boot), this simple advice usually does the trick without the need to send people for X-rays or for a surgical appointment.

I've found that two exercises in particular help a lot. In the first, you lie on your tummy on the floor with your head to one side. You clasp your hands in the small of your back, then you lift your shoulders and straight legs upwards, so that you are forming a bow, looking upwards, with only your stomach touching the carpet.

Hold that for a few seconds - as long as you can - then relax. Do it again after a minute or so, and repeat for about five to ten times. You will find it difficult to do at first, because your muscles will inevitably be stiff, but after a few days you will begin to notice the difference.

After this exercise, roll over on to your side and stand up, keeping the small of your back hollow as you do so. Stand facing the wall at arms' length, so that you are not leaning either backwards or forwards, and place the palms of your hands against the wall.

Keeping your elbows straight, push your hips in towards the wall. Hold them there for a few seconds, then straighten up again. Repeat the exercise about ten times in a few minutes. You will be amazed how quickly you will loosen up those muscles.

Doing these exercises two or three times a day for the rest of your life may well keep the back pain at bay. You may even grow half an inch taller as the muscles relax and stop compressing your spine!

I'm pleased to report that a review in a prestigious American journal has found that doing exercises like this is essential to successful back pain treatment, as long as the patient is also taught about why back pain occurs and how it can be relieved, and given support from several members of the GP team.

Warming the lower back at times of pain also helps. The report says that the benefits of manipulation are modest'. As for painkillers, they are classified as moderately effective' so that most people can expect only a twenty percent improvement in the pain. Steroids, the authors write, are no help at all'.

  • Living With Back Pain (Overcoming Common Problems), by Tom Smith, is published by Sheldon Press at £6.99.