27 world records were broken during the 2016 Summer Olympics. They fell in swimming running weightlifting and a number of other sports. But how do athletes continue to get better, jump longer, run or swim faster? Although scientists say that athletes have reached their limits (极限), records continue to fall. In almost every sport, athletes have become better since the Olympic Games begin.

    One reason is that and more people than ever beforehave access tosports and exercise. They start at an earlier age and can compete longer in their sport. In schools more and more natural talents can be discovered.

    Besides, athletes can train full-time instead of training after works. As medicine improves, athletes can stay in competition for a longer time and overcome injuries (损伤) faster. Many top athletes achieve their best results later on in their careers. Technology has also helped improve scores.

    One of the most important reasons, however, is the human mind. We always want to be better and faster that someone else. It can release (释放) great power in our body.

    So, where are limits? One of the most difficult questions to answer is how fast a human being can run. Many years ago, nobody thought a person could ever run within 10 seconds in the 100-metre race. But the record was broken at the 1968 Mexico City Olympics. A t the moment Sustain Bolt is the fastest man on Earth at 9.58 seconds. Scientists say that 9.48 may be the limit, but, who knows, maybe some runners will one day run within 9 seconds.