单选题：The Science of Sport　　1　At the 2004 Olympic Games in Athens,

The Science of Sport
　　1　At the 2004 Olympic Games in Athens, the Chinese athlete Liu Xiang equaled the
　　world record for the 110 metres hurdles （跨栏） when he ran the race in 12.91 seconds. This record time had been set in 1993 by British sprinter （短跑运动员） Colin Jackson and 9 years went by before another athlete was able to run as fast.
　　2　Record-breaking in all track events is slowing down and we appear to be moving much closer to the limits of human performance. Nevertheless, every four years, records which were previously thought to be unbeatable are broken. So what's behind this never-ending improvement in performance? And how long can we keep breaking records? Is there a limit to human performance or will athletes continue to gain seconds?
　　3　Most experts agree that it isn't the athletes' bodies which have changed but the huge advances in sport science which have enabled them to improve their performances. The individual athlete obviously has to have the necessary skill and determination to succeed, but the help of science and technology can be significant. Research has brought a better understanding of the athlete's body and mind but the advances in sports equipment technology have also had an important impact on human performance.
　　4　Scientists have shown that an athlete's body's needs vary according to the type of sport. This research has helped top sports people to adapt their training programme and diet better to their particular needs. Running the marathon and cycling, for example, are endurance （耐力） sports and require a different parathion （硝苯硫磷脂） to that of a 100-metre sprinter. In some sports, changes in techniques have significantly improved performance.
　　5　But in any sport, a player's success or failure results from a combination of both physical and mental abilities. Most coaches use psychological techniques to help their athletes cope with stress and concentrate on their performance. For example, the English football team listens to music in the changing rooms before a game to help the players relax and not feel so nervous. Before a difficult match, tennis players are encouraged to use visualization （相象） techniques to build confidence and this is almost as good as practice.
　　6　But as science, begins to dominate sport, are we in danger of losing sight of the heart of the competition, the sporting challenge? What's more, are all these advantages fair?
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