Exercise is good for you. This is the gospel that we doctors are enjoined to preach to patients - we even have prescription pads to refer people to the gym.

But there is a snag: the more you exercise, the more likely you are to pick up a sports-related injury. We are taught from an early age that warm-ups and cool-downs are the best way to prevent this, but it is not entirely clear whether either routine does us any good.

The science supporting the notion is far from robust. A review of the evidence published last year by the international, not-for-profit Cochrane Collaboration suggested that warm-ups did not prevent injury or muscle soreness after exercise, while cool-downs did not prevent post-exercise pain either.

These studies involved only small numbers of fit, healthy people - the benefit for the less hale and hearty has yet to be established. Indeed, a review entitled "Does warming up prevent injury in sport?", published in Sports Medicine Australia in 2006, concluded: "There is insufficient evidence to endorse or discontinue routine warm-up prior to physical activity to prevent injury among sports participants." The paper did suggest that more work was needed to define the relationship between warm-ups and injury. So far, no compelling evidence has appeared.

So what would help? The British Medical Journal recently published a paper examining the effects of "neuromuscular training" on female players of floorball (a sport similar to hockey) in Tampere, Finland. The women were trained to improve balance, posture and control during fast, zigzagging manoeuvres. The number of non-contact injuries among this group was significantly lower compared with a group that had not received the training. This kind of research is certainly useful, although it needs to be replicated more broadly and in different types of sport.

Until then, I suspect I will continue to recommend walking as the best exercise. It can be done with minimal special effort, you don't need to buy any equipment and it's sociable. And because walking is so "normal", no one feels the need for a warm-up before they set off.

Margaret McCartney is a GP in Glasgow

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