Snow had fallen, so might you

The wisdom on winter sports injuries is handed down from skier to skier, and from one newspaper article to the next. That's how we all know that late-afternoon runs are the most dangerous, that you are most likely to injure yourself on the third day of your skiing trip, that snowboarders have more accidents than skiers. There is truth in some of this shared knowledge, but much of it cannot survive exposure to the facts - as collected by Medecins de Montagne, a network of 74 doctors working in 52 French winter sports centres.

Its statistics, apart from disproving myths such as the dangers of the third day, also throw up some strange-but-true phenomena in the pathology of the skiing injury. For example, women over the age of 25 are twice as likely as men to suffer from a rupture of the anterior cruciate ligament in the knee, now the most widespread serious injury among skiers - although women average the same number of injuries overall as men (another myth debunked). Snowboarders do suffer more injuries than skiers, but only because they are so accident-prone as beginners; when they have seven days' experience behind them, snowboarders are no more likely to be injured on the slopes than skiers. (In contrast, there is no discernible difference between the injury rate of experienced skiers and that of beginners.) And the British are no more injury-prone than other nationalities: "I suspect that British knees are the same as everyone else's," says Bernard Dupuy, one of six doctors working in the ski area of La Plagne.

Dupuy and his five colleagues supply to Medecins de Montagne information on the injuries in the La Plagne area, which have run consistently at 25 per 10,000 skiers day after day (the second and the fourth, as well as the third) for the last five years. They get back endless graphs showing the evolution of the ski injury since 1975, which Dupuy talked me through in his surgery up at 2050m in Belle Plagne.

They show, dramatically, the effect of developments in ski equipment. The graph for limb fractures is in the shape of a flattened "X": lower- limb fractures have fallen from almost 70 per cent to about 25 per cent, with upper limbs doing the opposite. The curves cross in the early Eighties, by which time most skiers had rigid plastic boots and easy-release bindings to protect their legs. But with the new bindings, arms and shoulders hit the piste harder; and snowboarders - who break a lot of wrists - have topped up the recent figures for upper-limb fractures.

Tight-fitting plastic boots have had another striking effect. By protecting the ankle and lower calf, they transfer the shock of a fall or other impact up to the leg's weakest point, the knee; and although damage to the anterior cruciate ligament was almost unknown in the early Eighties, it now accounts for 10 per cent of all skiing injuries in France - about 13,000 cases a year.

"The problem is," says Dupuy, "that the knee is not nearly as well designed as the ankle, and has to be held together with these ligaments. If I had a leg injury, I would much rather break an ankle than damage my knee: an ankle will heal completely in a few months, but knee damage can stay with you for the rest of your life." Dupuy does, however, still see broken ankles: "The soft boots which snowboarders now use are bringing back the injuries which I used to see with skiers when I started my practice 20 years ago."

What about the far higher incidence of anterior cruciate ligament injuries among women? "I suspect that it's a problem of female anatomy," he says. "The hips are wider, so the hip bone is more sharply angled into the knee. But we simply don't know yet."

Among the variables affecting the likelihood of injury, time is important. But the afternoon, between 3pm and 4pm, when skiers are tired, is not the only danger period. "There is another peak at 11am," says Dupuy. "This may be because people don't eat enough at breakfast to compensate for cold weather, which uses energy more quickly." Bad weather, however, does not seem to be an important factor - "perhaps because it makes skiers more cautious. But although their incidence stays constant, the injuries change with the conditions. Broken hips and shoulders tell me the snow is icy; more twisted knees and sprains, and I know there's soft, deep snow.

So what, apart from having a big breakfast, can a skier do to avoid injuries? If you are a woman, slacken the grip of your bindings: for the last two years Medecins de Montagne has recommended this to lessen the danger of knee ligament damage. If you are a child, wear a crash helmet: the high incidence of head injuries among children, partly a result of their heads being proportionately larger than adults', led to the Skiez casque campaign for under-16s in French resorts - which has cut head injuries by 40 per cent, at least among skiers (early teenage snowboarders are too cool for crash hats).

Dr Dupuy's regime for healthy skiing is as follows. "Skiing is a sport; and as for other sports, you should eat well, drink well - water, not alcohol - and get plenty of sleep. But avoid sleeping pills: at altitude people often sleep badly because of the thinner air, but the pills will make you drowsy in the morning, so you won't ski well. And, most important, you should exercise for a couple of months before going skiing."

He is not talking about exercise for better skiing, so much as for better falling. "People who have trained muscles can control themselves when they are falling. I see people here who cannot get up off the couch without help because their stomach muscles are not strong enough. When they fall, they are out of control."