SOME of the toughest, fittest people in world sport are in the territory this weekend to thrill thousands of rugby fans at the Hongkong Rugby Sevens. Brilliant as they are, they have one thing in common with Hongkong's more humble sportsmen - they are prone to injuries that can disrupt and even end their competitive careers. During last year's tournament, the physiotherapist unit tended to 92 players for an assortment of sprains, ligament injuries, bruises and dislocations. Six players had to be taken to hospital. ''Some of the things we see are fairly serious, like when joints are wrenched into a strained position so the supporting ligaments become damaged, head injuries, concussions or the occasional dislocated shoulder,'' said Ms Janice Morton, a physiotherapist with Byrne, Hickman and Partners, the official Sevens physiotherapists for the past 10 years. ''More minor injuries include sprained hands, wrists and thumbs. In most cases they can go back and play, but there are still quite a few who are out of the tournament for the rest of the weekend.'' But the injuries can be more serious. In the 1988 Sevens, Dutchman Marcel Bierman was left paralysed from the waist down after a tackle. And two Hongkong stars, Stewart Brew and Gary Cross, have suffered serious ligament injuries. Cross hopes to be back in action within six months, but Brew will never play competitive rugby again. Up to nine physiotherapists work virtually non-stop during the Sevens weekend. Experts stress that taking proper precautions can go a long way to preventing injuries. ''It doesn't matter what sport you're playing,'' said physiotherapist Ms Lesley Hickman. ''It is most important to do stretches before and after, and also do preventative strapping techniques.'' ''This is not just bandaging, but specialised sports strapping. Most of the top teams, like the Australian, New Zealand and Fijian squads, all strap their ankles before they play, particularly over old injuries. ''If there are old injuries, strapping is done not to stop the player from having normal movements, but to prevent over-stressing the area. And while we do preventative strapping on the field, it is often better for the players to do it themselves as theyknow exactly the range they want,'' she said. Before the game, most players are out on the field stretching their muscles. ''They all realise the importance of general fitness, but the way they stretch is equally important. We find the top teams stretch properly, but the lesser ones are not as aware of how they should be preparing,'' Ms Hickman said. ''The players have to train quite hard, and the bulk of the injuries are for ankles, knees, shoulders and neck. But I had to accompany the Dutch player [Bierman] to the hospital when he broke his neck. Still, there are a few rugby players who get away with anything.'' During the weekend, the clinic gives the players rubdowns, preventative strapping, and neck and back treatments. A doctor is on call if players require more serious attention or need hospital treatment. ''We set up a fully-equipped physiotherapy department at the stadium,'' Ms Morton said. ''Ours is a big practice in Hongkong, anyway. We have six clinics around the territory, so we mobilise physiotherapists from all clinics. ''Before the weekend itself, any of the injured players from the Fiji Sevens, for example, can come to the Central clinic to be treated. That is why we insist that all our physiotherapists be sport-injury trained.'' The number of casualties often depends on the weather. ''Last year, conditions were treacherous,'' Ms Hickman said. ''If there is a little rain, the ground can be in good condition so if the players fall, injuries are reduced. If the ground is like concrete, and a player is tackled and goes down with others piling on top, it can be a bit more dangerous.'' Ms Morton said their presence at the Sevens was crucial. ''We have a doctor there to deal with the stitching and more serious cases. The physio room screens all the injured players, and if it is something that needs more attention the doctor reassesses and makes a decision as to whether stitching and medication is necessary.'' Another physiotherapist with the clinic, Mr John Moses, has been looking after the Hongkong team and has the players on a regimented system of dieting and exercise. ''We work mainly on the basis of a carbohydrate diet, and I advise them to stick to a vegetarian menu when they are going through a training regime, although meat is occasionally allowed when we get into competition. ''A couple of days before the competition, we get into a very high carbohydrate diet - lots of rice, vegetables and breads and specific foods designed for sports.'' Alcohol is not encouraged, if only because it causes the blood vessels to dilate in case of injury. ''I don't mind the guys having a beer, but I try to get them to realise it may not be such a good idea.''