Technical Analysis Room of Ersha Island.

The group was watching the playing video of Bolt, nodding from time to time.

This is Randy and Ralph. MAN built the latest data analysis after the Champion model analysis.

There are some freeze-frame stats on it:

According to the data, the fastest frequency of exchanging legs between the two legs when running is 3.1~4.85 times/second. This can be said to be very rare in his height.

Because athletes of such height are generally stride length types, and Usain Bolt is obviously a "special case".

He is actually the type of cadence, and the key is ...... His stride is basically due to physiological reasons, and it has both.

(1) Kicking power: F=mv/t(∵F=ma; a=(v-v0)/t and ∵v0=0 ∴a=v/t), since m represents the mass of the human body here is a constant, the greater the force of the pushback (F) per unit of time, the greater the speed of the human body (v).

(2) Kicking speed: If the kicking force (F) is constant, the speed (v) is inversely proportional to the time (t) of kicking off the ground, that is to say, the shorter the kicking time off the ground, the greater the speed obtained.

(3) The degree of leg straightening: it is mainly manifested in the three joints of hip, knee and ankle in a line, so that the reaction force of the ground to the human body can fully push the body forward through the center of gravity of the human body.

(4) Kicking angle: Due to the characteristics of the human body structure, the kick angle is limited, and reducing the kick angle is not only conducive to increasing the horizontal component, but also reducing the degree of ups and downs of the body's center of gravity. In addition, reducing the back pedal angle is also an important factor in speeding up the frequency of leg exchange.

(5) The direction of the back pedal force: the direction of the back pedal force should be consistent with the forward direction, such as the direction of the back pedal force to the left or the right side will produce a component effect, reduce the forward speed, and affect the linearity of the body's center of gravity movement.

Then bring in Bolt's physical stats and athletic stats one by one.

Under the "Champion Model" display, in the final of the Beijing Olympic Games, Bolt's various data changes:

The applied force of F/N, 804.7, is a significant increase compared to the previous 2007 level.

The maximum speed is 12.04s, which is also significantly higher than the previous year.

The starting acceleration is 9.36, which is still a significant improvement.

The peak output power is 2554.35, which is nearly 100 points higher than last year.

The overall work is 80.465, compared to 07 ↑.

The efficiency of the work is 6.235, which is still a significant increase in unit efficiency compared to 07.

Swing leg front swing angle / ° at the beginning of hip feeding: 62.3.

Swing angle of the leg body before swinging at the end of the hip delivery / °: 77.

Swing leg swing angle/° from the beginning to the end of the hip feed: 14.7.

At the beginning of the hip delivery, swing the front knee joint of the leg body fan angle / °: 50.8.

At the end of the hip delivery, swing the front knee joint fan angle of the leg body/°: 78.3.

Difference between the fan angle of the knee joint at the beginning of the hip delivery and the end of the hip delivery: 27.5.

……

Seeing this dense data display on the big screen, even these "battle-hardened" veterans and coaches feel that these data are too ...... I went into more detail.

The summary of the previous competitions, compared to this, is at the level of elementary school students.

"It took 41.25 steps in the Olympics." Randy watched the video on it and toggled the progress bar little by little, saying, "2-6 steps less than the rest of the players, which shows Bolt's super long stride ability." Cadence + stride length, he is currently the most perfect one. ”

"At the Olympics, the knee angle of Bolt's support leg is 157.1° and 146.8° in the vertical phase, respectively."

"The path deviation of the launch is very small and quite straight."

"When the knee moves forward, his hip rotates inward and there is a lot of lateral shift in the center of gravity."

"His starting stance is also obviously not compact enough, but it is unconventional and a little relaxed."

"I think it's because he adopted a compensatory strategy to maximize the initial speed at which the force is generated at the beginning."

"Look at Usain Bolt's scavenging." Randy clicked on the video, played it for a while, and paused again: "Look at his feet, the quality of the center of gravity changes, he doesn't seem to put his feet under the center of gravity, I think the only time he can put his center of gravity down should be in the starting stage." This means that the closer the foot is to the body's center of gravity, the faster the person will be able to complete the running cycle, and the faster the performance will be. ”

"And the problem of Bolt's hip lift." "I think that's key," Randy said. ”

"A lot of our athletes put too much emphasis on cadence and neglect adequate hip movement, so that momentum is lost in the progressively decreasing stride length, which affects performance."

"And Usain Bolt's vertical oscillation, which is small." Randy tapped a small wooden stick at the corner of the screen, just in front of Bolt's running style, "Because minimal vertical swing usually reduces the pressure on the joints and increases efficiency during the run." ”

"These are some of the points that we neglect in training."

……

"Okay, let's see how our athletes compare the data from this Olympics." Randy typed a photo of Lao Yi on it, and said: "First of all, we don't have too many problems with Lao's future positioning from a physiological point of view, although Lao's height is 25CM shorter than Bolt's height difference, but we can see that even so, Lao's stride length index is still 1.249 over Bolt's 1.245." This shows that Lao should indeed walk stride flow as the main and cadence as the auxiliary. It also reveals a major reason why Lao's future is so strong. ”

Can Labor and Rest actually overtake Bolt in the stride index? Really.

But in the previous country, I am afraid that no one would dare to talk nonsense.

For fear of misjudgment and a huge public opinion attack.

"But while Law has an excellent stride index, his cadence index is quite bad." Randy seriously analyzed the data model to all the coaches and athletes on Ersha Island: "The difference is 0.554. ”

"Lao, your future should not only strengthen your future, but also your entire cadence, so that you can run faster."

Although Lao Yi didn't understand it so well, when it came to himself, he still listened more carefully than ever.

lest he finally get mixed up with the fourth 100-meter chair of Ersha Island, so he gave it up.

"The angle of your landing on the road is 65.3, which is five or six percentage points less than Usain Bolt. The smaller the landing angle, it actually means that Lao's 'ground picking technology' still has a lot of potential to be tapped. An analysis was displayed on the screen, which reads: A small landing angle means that the vertical projection point of the person's center of gravity is farther away from the landing point, which will inevitably produce a greater support reaction force opposite to the direction of running, causing a loss of speed in the horizontal direction and affecting the running speed.

The knee angle angle of the support leg of 148.3 became 140.4.

In this way, the change range of the two actions is too small, only 7.9.

And the knee angle of these two technical movements, Usain. Usain Bolt is the most obvious, his data is more than twice as direct as that of Laoyi. This shows that the muscles of Bolt's support leg are more actively retreating, and because of this, the active muscles of the support leg during the buffer period are passively elongated, the initial length of the muscles increases, and the contact area between the cross bridge and the site increases, which increases the muscle tone. As a result, it is possible to change the direction to preserve Bolt's muscles during the back pedal phase, and exert more contraction power and speed.

How to do it, Randy looked at Su Shen below and asked him to come up and explain together.

Su Shen was not polite, walked up to the audience, and said: "The next thing you have to do is to speed up the swing speed of the swinging legs, which can effectively improve the cushioning and pushing speed, and can also shorten the game time, and finally get the strategy of increasing cadence." ”

"Big bull, the minimum knee angle of the pampered swing leg is 25.5, and it can be seen that your swing leg is not folded enough, which will affect your forwardness. This year, until the end of the winter training, your swing leg folding technique should also be re-condensed, remember to try to use the swing to promote the pedal, pedal swing combination. ”

"Okay, I know Brother Xiao Tian." When Lao Yi heard this, he silently took notes.

Although he may not be so good at theoretical knowledge, Randy's method of replacing data with video and then text analysis allows many players who are not so good at digesting theoretical knowledge to quickly enter the state.

Understand where you're doing wrong and where you need to keep improving.

"Brother Kai, this is your Olympic stats, especially in the vertical phase of the moment of landing, Bolt's knee angle changes by nearly 20. And Brother Kai, you're only in your early 10s. This shows that the support leg has changed from centrifugal contraction to centripetal contraction, Brother Kai, you have not done enough. There is still room for strengthening. ”

"If you look at your cadence and stride length for the entire 100 meters, it's still a little too fast." Su Shen said: "This will make your back not play to the real extreme, and the overall performance will be less optimized and slower." In particular, between the eleventh and fifteenth steps, the instability is more pronounced. If you can stabilize it, you may have to improve after your results. ”

Hu Kai also pushed his glasses.

Looking at his various running data on the entire projection screen, he also nodded silently after patiently reading it.

There was no such detailed data analysis system before.

Therefore, even if you are a coach, you can only look at the feeling.

But now Randy has brought science and systematization, which has greatly improved the team's observability.

Under the champion system model, Hu Kai has a clearer and more visible understanding of his own shortcomings.

It's really clear at a glance.

It doesn't matter to the new team members, they don't have enough understanding of this system, and they don't have a deep feeling.

But for the veteran players, they can clearly feel the kind of "change" that is earth-shaking in the post-game review.

In the past, how could the "post-match review" be so detailed, but now...... Everyone has a whole bunch of things to remember.

This is the benefit of systematic science.

Clear, clear, what the athlete wants to improve, and sometimes even look at the gaps in the data, that's enough.

……

"Haohuan, let's take a look at your set of data, your height is about five centimeters shorter than Bolt, but as a big man who is also more than 1.9 meters, the angle between your legs and the angle of your swinging legs are obviously different from Bolt. Bolt's leg angle and swing leg angle in this final are 96.8 and 12.1, respectively, while you are 100 and 11.1, which says a point. Su Shen clicked the continue play button, which showed another line of analysis, and said: "The back kick, knee angle and your support time in the back press phase are too long, so the angle between your legs and swing leg angle are weaker than Bolt's." ”

"Even considering the physiological segmentation curve, we think that if you correct this aspect well, it should be faster."

"The specific method is to strengthen your leg hinge, appropriately reduce the angle of the back pedal, and shorten your support time, which is our analysis of the championship model calculated based on your four shots and 100 meters in this Olympic Games."

Zhao Haohuan looked at it, touched his chin with his hand, and intuitively compared that he and Bolt were put together, and they could indeed see a lot of faults under the high-definition close-up shot. And compared with the past, the current adjustment is more detailed and more high-end.

This is an adjustment after the athlete has progressed to a higher level.

It's not just about tweaking a technical move.

Each of these body data may have to be turned out and compared and viewed one by one.

As for why Usain Bolt was used.

Needless to say.

Because Usain Bolt is the fastest.

Not only now, but also in the original timeline, it is also Bolt who has been pulled out for analysis and comparison countless times.

If a person runs the fastest, then any set of his running data has the significance of absorption, analysis and reference for scientific data models. This is also the reason why Su Shen must introduce the "champion model theory" to China.

Otherwise, there is no scientific data model theory to guide them, and they only rely on the so-called coaches' experience summary.

It's a little too old.

In Randy's original words in the afterlife-

"I often tell some coaches not to argue with me about science. What I'm telling you now is something that scientists all over the world have already recognized, and you just have to do it. It is basic common sense that you cannot create a new training system without the integration of scientific knowledge such as training psychology and biochemistry, human mechanics, etc. ”

"Education is not to encourage flower growers to go to the United States to learn, because a lot of knowledge is placed, and it is all Chinese, and only coaches need to go to the classroom to study seriously and systematically...... I think the flower grower should let all the coaches participate in scientific training, and if they don't go through the classroom training, they don't give them a diploma. Let the coaches understand that this is my profession, and all our coaches must be professional. ”

Referring to Randy's words, training is truly scientific, and it is necessary to have real scientific reserves to get out of the "empirical trainingism" that has dominated the track and field training system for decades or even longer. And it's not alone, it takes a lot of smart minds to work together.

After all, there is always a limit to a person's mind.

Even if it was Su Shen himself, if he hadn't reopened, then he wouldn't have been able to do so many things alone.

And in the later stage, even he needs a strong and stable team and laboratory to constantly innovate.

The most taboo thing about sports science is to be complacent.

Thinking that things are the best, and then no longer going beyond and breaking through, then the meaning of the scientific movement will be lost.

"In the end, it's me." Su Shen asked Randy to come back to them, but Randy waved his hand and refused.

Because of Randy and Ralph. Man hopes that Su Shen can come by himself.

For them, bringing out a few excellent athletes, although there is also a high sense of achievement, but ...... The highest sense of accomplishment is to help a country create an overall scientific sports system. And these are ultimately up to the natives.

Seeing the two of them say this, Su Shen had nothing to say, nodded, and continued to say to the video playing: "This is my four shots in 100 meters this time." ”

"As you can see, from the preliminaries to the finals, within four shots, the number of steps is actually increasing slightly, the average cadence is also increasing, and the average step length is decreasing. In other words, my cadence index increased as the race progressed, and my stride length index decreased. ”

"The following shows the segmented cadence changes in the 100-meter running process of my 4 guns in the North Olympics, which can be divided into two situations: one is the three stages of frequency increase-hold-decline after the start, showing an inverted "V" shape. The other situation is the increase in frequency after the start - hold - drop - increase frequency - drop again, and the cadence change trend of the whole process presents an "M" shape. ”

"Considering the relationship between excitation and inhibition of the nervous system, the high-cadence running method, in the process of running quickly throughout the whole process, often cannot appear many times and maintain a very high cadence, and considering that the former one mainly appears in the preliminaries and semi-finals, and the semi-finals and finals are all M-shaped types, so I think the latter is in the high-intensity confrontation, and may be more meaningful for research under the current physiological conditions."

"And now it's the same comparison Bolt." Su Shen pressed the pause button, and a running picture of himself and Bolt appeared on the big screen, and said: "We can see that Bolt has been running for a long time or distance from the 6th ~ 35th step in the Beijing Olympics, and the cadence of this 100-meter run is unchanged for a long time or distance. The rest of the players, including myself, had a big up-and-down in these segments. My words, especially after 60 meters, the fluctuations become more and more obvious. ”

"So what does this smaller fluctuation mean, look at this set of data, when Pele broke the world record, the change in cadence throughout the whole process was very small, and the difference between the maximum and minimum cadence of the whole course was only 0. 1 step/second, the first 10 meters reach 4. 63, keep it until 30 meters, from 30 ~ 60 meters his cadence rises to 4. 72 steps/sec, in the last 60 ~ 100 meters cadence back to 4. 63 steps/sec,. Su Shen looked at the big screen seriously and said, "So his whole cadence change line is almost a horizontal line." ”

"So we're going to make a hypothesis. Compared with the rest of the players, Bolt's cadence is low throughout the whole course, can the lower cadence be maintained for a longer time and not be easy to fatigue? Clicking the mouse, Su Shen said: "Although Bolt is a cadence type, but because of the physiological conditions, his stride is naturally large, for example, he runs 40.5 steps in 100 meters, and others run 49 steps, from the perspective of energy distribution, you only run about 80% of his distance." According to the data, we can find that whether it is a Chinese athlete or a foreign athlete, as long as the six-second rule is correctly activated, then basically the vast majority of their athletes will start to slow down at the 30-34th step. If you have a large stride length, 27 steps to 60 meters, then you may have to be 80 meters away to enter the physiological natural deceleration stage, if you have a small stride length, 32 steps to 60 meters, then about 65 meters you will naturally start to slow down. Due to the excitation and inhibition mechanism of the nervous system, it is impossible for people to maintain a high frequency for a long time, and the 100-meter run can only be completed by rising and falling the frequency in the whole process, so how to stabilize has become a key. ”

"But isn't it better to stride as long as possible?" Su Shen looked down and said, "That's definitely not." ”

"Because even with a stride, it's not for nothing to surpass Usain Bolt, like Blomfield (39 and a half steps in the 100m). If you consider the physiological proportions of the human body, look at the stride index, Gatling, Bailey. Cole, Mike. Rodgers and so on are better than Usain Bolt. Therefore, the idea of simply expanding the stride length in China is not suitable for everyone, reducing and eliminating the redundant "expanding stride", cadence + stride length is the best. After all, the essence of modern sprinting is the relaxation technique in high-speed displacement based on pedaling, so we need to determine that it is the future trend to create a different golden stride cadence ratio for each person according to the physiological conditions of the human body. ”

"Our country has fallen into the trap of people who usually regard stride length and cadence as "cause" and running speed as "effect", that is, people usually think that "what kind of stride length and cadence there is, what kind of running speed will occur". Su Shen said: "Most people start from the perspective of optimizing cadence and step length, and study the improvement of special speed. However, there is no direct causal relationship between cadence, stride size, and specific speed. Running speed belongs to the kinematic parameters of the horizontal displacement of the center of gravity of the body when the athlete is in the running state, but the step length and cadence belong to the spatiotemporal structure parameters, and the two sides describe the kinematic indicators of the athlete's running from different perspectives. ”

"So what is the best way to do it? There have long been similar sayings, such as reasonable speed = 94.12.9% of the athlete's maximum stride length × 95.1±3.5% of the maximum cadence. Therefore, in the future, we will also work mathematical model research. If you want to consciously promote the increase of step length and the reduction of single step time, in fact, the continuity of running power and the systematic and mutual aid of each link must be destroyed, which will have a negative impact on the running speed of the human body. In fact, for sprinters, their running speed will be mainly affected by the ability to relax and swing at high speed, so in the future related research, we should pay attention to the kinematic parameters that reflect the high-speed swing ability of the human body, and carry out in-depth exploration around them to be more scientific and systematic. ”

Randy listened below, nodded and said, "Do you run the whole person as a whole machine?" That's an interesting point of view. Right, old man. ”

As he was talking, he saw Ralph. Mann fell into deep thought.

Don't take care of Randy next to him at all.

Because Su Shen's statement provided him with a new idea, it is true that everyone now pays too much attention to the study of simple stride, cadence and speed, in fact, forgetting that the body is a whole and is the most sophisticated instrument in the world. If we study it as a whole, will we be able to find more paths and methods in the future?

"Looking at my own side, the moment of landing in the Olympics and the vertical stage of Bolt's support leg knee angle, in fact, we can clearly see that because of physical fitness and performance reasons, the 40-50 meters of the gun in my final is obviously deviated from the semi-final data in the middle running stage, compared with my own current data collected by the championship system, it is offset by 10~5 respectively."

"This shows that the stability of my land is still lacking."

"And this problem can actually be optimized with a new technical concept."

Technology?

As soon as they heard this, everyone was excited, and they all looked at Su Shen, and little stars almost popped up in their eyes.

Even Randy was stunned.

It's obviously a summative analysis meeting, but how did it turn into a direct conclusion and the launch of a new technology?

That's what you do.

We're going to be coaches in the team in the future, and it's very stressful, so it's very difficult.

Su Shen inserted the PPT he had made, and after the computer began to read the USB flash drive, he said, "This is it." ”

"In the future winter training, we will let a group of qualified people start training to enhance their ability to run and pick up the ground on the way."

And at this time, on the big screen, a few big words were written————

Optimized "credit card" landing technology.

PS: This type of chapter is not easy to write, hahahaha, it's so slow to write, but I believe that in this way, the sense of realism can explode. And it is logical to take the opportunity to improve and launch new technologies~~~~

I hope you will support you a lot and help Xiaozi read the paper late at night to burst the liver ing~~~o(╥_╥)o~~~