A training ground for a sprint group.
Xue Li looked at the field and asked: "I have seen your resume. You just graduated three years ago, majoring in sports training. You should have been exposed to sprint-related training in school, right?"
Dai Li nodded: "I have learned some, but it is all superficial."
"I know that I personally participated in the compilation of many sprint-related textbooks commonly used in universities. To be honest, those things are outdated. Now is the information age. In all walks of life, various new technologies are emerging one after another. Sports The same is true for sports. The main purpose of so-called records is to be refreshed, and athletes are really taller, faster, and stronger." Xue Li said.
Dai Li didn't know what Xue Li was going to say, so he could only nod silently and listen carefully.
Xue Li then asked: "What you learned in school is that sprinting emphasizes kicking skills, right?"
"Yes, the textbook requires athletes to straighten their hip, knee and ankle joints as much as possible when pushing off the ground in order to obtain higher pushing force and achieve faster speed." Dai Li replied.
"Well, more than ten years ago, I thought the same way. We thought it was best for athletes to push back at a knee angle of 180 degrees, so the textbook just said that. But now with the latest technology, we don't require athletes to push it too far. Kick the legs straight, what we are pursuing is a 'bending kick' technique." Xue Li explained.
"Bend-pedaling technique? Does it mean that the back-pedaling leg is not completely straight?" Dai Li asked.
"Yes, we once thought that back pedaling was the only source of power for sprinting, but this conclusion placed too much one-sided emphasis on front support and resistance, and even more one-sided emphasis on rear support power. Until the emergence of Gittel, our thinking changed. Cognition." Xue Li said.
The Gittel that Xue Li mentioned comes from Jamaica, which is a capital of sprinting and has produced many world-class trapeze artists. Among these trapeze artists, Gittel is undoubtedly the best, including relay races. He won nine gold medals in three Olympic Games. He broke the world records in 100 meters and 200 meters many times. No one can shake the world records he set. Although Dai Li has never seen Gitel in person, he has already determined in his mind that Gitel's talent has definitely reached the top S+ level, and in fact, he has indeed dominated this era!
Just listen to Xue Li continue to say: "What Gittel uses is the bending pedaling technique. The knee angle of his supporting leg changes very little from vertical to back pedaling off the ground, and his center of gravity is very stable. This Some of them are beyond our understanding. It is almost impossible to maintain a stable center of gravity when pedaling violently."
"Later we discovered that we over-emphasized a certain link, and sprinting technology is actually an organic whole. We over-emphasized the resistance of the front support and the power of the rear support, which resulted in athletes having front and rear thigh problems. In the case of an imbalance in the proportion of cluster strength, the strength of the rear muscle groups seriously lags behind the strength of the front muscle groups, causing the point of emphasis to be close to the center of gravity projection point, so as to ensure that the body's center of gravity moves quickly to the support point. However, this will prolong the title time. Cadence dropped!"
Xue Li's explanation would definitely sound confusing to an outsider, but to Dai Li, there was a sense of sudden enlightenment. Just these few words made Li Dai feel that he The awareness of sprinting techniques has been raised to a whole new level.
Xue Li went on to introduce: "At the same time, our research also found that Gitel's power relies not only on the ground, but also on the forward swing of the legs. In our previous understanding, the ground is the driving force and creates speed, and Cushioning is resistance and speed is lost, so we have always emphasized increasing the force of the back pedal, the length of the pedal, the direction of the pedal, and the speed of the pedal.”
“But when the bent-pedaling technique is applied to sprinting, the previous theory that emphasized straightening of the pedaling no longer exists. At this time, focusing on the forward swing technique and strengthening the combination of forward swing and pedaling becomes the only way to increase speed. Therefore, the latest sprinting technology currently used by our national team is based on the technical theory of pendulum, using pendulum to promote pedaling, and combining pendulum and pedaling."
"You must know that when an athlete is standing, he can only push on the ground, and the thrust is vertical and upward, which cannot promote the migration of the human body. But if the athlete bends his knees and swings his legs forward and upward, the center of gravity will inevitably shift and the body will lean forward. , if you want to maintain the body's balance at this time, you need to support the leg to achieve it. At the same time, the original supporting leg will generate a downward pushing force on the ground, which will once again prompt the body's center of gravity to move forward, thus completing a double step. This is the swing. The basic principles of pedaling.”
Dai Li nodded: "I understand. To put it simply, in our previous training concept, pedaling was the source of power, and the front swing was just to control the direction of travel; but in the current training concept, the front swing is the power, and pedaling is the source of power. The ground is also the driving force, and the two are combined. It seems to be the difference between rear-wheel drive and four-wheel drive."
"That's very well said! The car example is very appropriate." Xue Li looked at Dai Li with admiration. He thought to himself that he was indeed right. Dai Li was indeed very talented.
Dai Li has more than just a plug-in in the coaching system. He is talented and good at learning. He usually works hard. After several years of work experience, he has learned to think proactively instead of like just now. Just like when I graduated, I copied the contents in the textbook.
Before Xue Li finished speaking, he used a teacher's tone and went on to introduce: "Sprinting is a complex biomechanical activity involving a variety of forces. Since humans are upright animals, pushing hard to push a relatively stationary object It is easier to push an object than a relatively moving object, so it is easier for a sprinter to accelerate in the starting stage. However, when the athlete's speed continues to increase, for the human body, because the acceleration time becomes shorter, the effect of continuing to increase the back kick becomes It’s more difficult. At the same time, when the speed increases, you have to face greater air resistance and braking resistance.”
"People can't grow streamlined, so air resistance is difficult to solve. Americans use high-tech means to make a fuss about athletes' competition uniforms to reduce air resistance, such as those one-piece tight-fitting sportswear made of nanomaterials , which was once sought after and imitated all over the world.”
"But since Gittel from Jamaica came out, they discovered that small tricks like tight-fitting sportswear are not worth mentioning in the face of absolute strength. Gittel was wearing an ordinary vest and shorts and still ran faster. Americans are faster. So a strong body and better skills are the most critical factors in improving performance."
"As for braking resistance, the essence of reducing braking resistance is to reduce the speed of the landing foot relative to the ground. The closer the landing foot is to 'zero' at the moment of landing, the better. The instantaneous speed of the landing foot of Chinese athletes is about 1.35 meters/second. That’s 17 percent more than American athletes, and that’s where we need to continue to improve.”
After Xue Li finished speaking, he pointed at an athlete running past in front of him and asked: "Look at him, what is he doing well in his foot landing movements, and what is not good enough?"
Li Dai knew that this was an on-site test question that Xue Li asked him, so he immediately observed it carefully.