If you have ever had backache, you may know the initial relief when the pain subsides, only to suffer a nasty shock when it comes back. Those who are in the habit of taking a walk will find their back aches much less frequently, according to new medical research. And the great news is that your walk need not be especially athletic. Scientists in Australia prescribed a walking programme for a group involving hundreds of non-athletic adults who had recovered after suffering from non-specific lower back pain. Half undertook the exercise – walking for at least 30 minutes, five days a week – while …