In the past three years, Beijing Jishuitan Hospital has been receiving more and more patients who suffer from knee injuries caused by jogging. Guo Xianfeng, director Guo Xianfeng of the hospital's Department of Physical Rehabilitation, said that jogging has become the No.2 cause of injuries next to skiing in China.

There were 47 marathons all over China in April with 17 happening on April 15 alone. By contrast, China only witnessed 51 marathons in 2014. However, the sport has grown so quickly that the number grew to 1,102 in 2017, an increase of almost 21 times in just three years, according to Tencent Sports.

In addition, more and more Chinese people have fallen in love with jogging as they run in parks, campuses and along roads. Many then post how long they ran as well as how much time they spent on social media. The country's State Council expects the sports population to reach 435 million by 2020.

Dr. Sun Yang from Beijing Sport University, who has been offering medical service for many marathons, says most of the people seeking medical treatment after long distance races were those lacking scientific training. Some had only jogged for five or ten kilometers before rushing to participate in half- marathons (about 21 kilometers).

Sun found the same problem with lack of proper preparation even among professional runners. If a runner who is used to making three long-distance races a week increases the number to six, the chances of getting sports injuries will be magnified.

Sun interpreted lack of scientific training as not increasing running practice gradually. He does not think it's good for amateur runners to jog every day. She suggested four times of aerobic exercise a week, which means at least 24 hours of resting after each running, as the best option. During the intervals, people can do some strength exercises to build up a stronger lower body which can ease the impact on their knees.

As for amateur runners who register for marathons or half-marathons, Sun suggested that they should finish at least one or two distances required by the event one month before in a gradual process with no bigger than a 10 percent increase in distance every week.

Director Guo believes that running is a process when different joints of your body collide with each other. If the damage caused by the collision does not surpass the rehabilitation of the system, your body will not get hurt and can get stronger.

If the damage goes beyond rehabilitation, your body will suffer from injuries. At this moment, Guo suggested that you should stop the exercise at once and start a rest-cure. Normal damage may take at most two weeks to recover. If the injuries are not getting better in two weeks, the runner should seek professional help at a hospital.