The Su God of the Reopening of the Sports Arena

Chapter 2451 Did you see that?! The arms display begins.

Why is there a problem that just can't be solved?

After Moscow, Mills also wanted to upgrade Bolt, and starting the upgrade seemed to be the best and most effective approach.

It's just a pity.

It's been blocking the way in one place.

This made Mills somewhat anxious.

The place Mills couldn't get past was called...

Dynamic balance of joint torques.

From "torque imbalance" to "coordinated matching".

This also works well with Bolt's three-joint torque technique.

It's just a pity.

Difficult to break through.

Because joint torque is the rotational effect of muscle force acting on the joint, its balance directly affects the stability of movement and the efficiency of force exertion.

Tall athletes, due to their longer limbs, are prone to "torque imbalance" when starting with a straight arm. Starting with a bent arm can achieve "coordinated matching" of joint torques by adjusting the joint angles and the timing of force exertion. Specifically, this is reflected in the optimization of joint torques in the upper limbs, lower limbs, and trunk.

It's a great thing no matter how you look at it.

Once completed.

Firstly, the upper limb joint torque can be easily resolved by transitioning from "high load support" to "low load transition".

Upper limb joint torque, mainly including elbow joint torque and shoulder joint torque, plays a core role in maintaining body balance during the starting phase.

In the past, when Bolt started with straight arms, the upper limb joint torque of tall athletes exhibited a "high load support" characteristic, making it impossible to achieve true golden starting balance.

The ability to start with a bent arm can be achieved by shortening the lever arm.

Reduce the load on the joints of the upper limbs.

To achieve a functional shift from "support" to "transition".

Moreover, Mills calculated that, in terms of elbow joint torque, when starting with a straight arm, the elbow joint is in an extended state, and the torque generated by the supporting reaction force is the "elbow extension torque," which requires the triceps to exert continuous force to maintain balance, with a torque value of 85-95 N·m.

This exceeds the optimal range of force exerted by the triceps, which leads to faster muscle fatigue.

If Bolt starts with his elbow bent at 90°-100°, the torque generated by the supporting reaction force will change to "elbow flexion torque".

The force is shared by the biceps brachii and brachioradialis muscles, and the torque value drops to 55-65 N·m, which is within the optimal range of muscle exertion. At the same time, the direction of the torque is consistent with the direction of "elbow flexion force" in the subsequent arm swinging movement.

This avoids the "torque direction conversion loss" when pushing away with a straight arm.

It can increase Bolt's swing arm starting speed by 25%-30%.

That's all!
Because that's the biggest problem with being tall.

It's a huge improvement.

Whether it's theory or not.

They are all too tempting.

If this is combined with shoulder joint torque, such as when starting with a straight arm, the shoulder joint is in a forward extension state. The "forward extension torque" generated by the supporting reaction force needs to be balanced by the continuous force exerted by the posterior deltoid muscle. The torque value reaches 75-85 N·m, which can easily lead to tension in the muscles on the back of the shoulder joint.

When starting with bent arms, if the shoulder joint angle is adjusted to 130°-140°, the "adduction torque" generated by the supporting reaction force will be borne by the middle deltoid muscle.

The torque value drops to 50-60 N·m.

Matching the torque direction with the subsequent "adduction-abduction" movement of the arm swing reduces the "direction conversion cost" of muscle force exertion.

Shoulder joint swing efficiency is improved by 20%-25%.

Mills believes that if successful, the range of torque fluctuations in Bolt's upper limb joints during a bent-arm start, and the difference between the maximum and minimum torque values, will decrease from 35-45 N·m with a straight arm start to 15-25 N·m.

Since then.

Stability will be improved by 40%-60%.

can.

It effectively avoids motion deformation caused by torque fluctuations.

At this point, the lower limb joint torque can shift from "single dominant force" to "coordinated force exertion".

As is well known, the torque of the lower limb joints, namely the torque of the hip joint, the torque of the knee joint, and the torque of the ankle joint, is the core source of power in the starting phase of running.

During Bolt's straight-arm start, the lower limb torque of tall athletes exhibits a "solely dominant knee joint" characteristic.

If you adopt a bent-arm start, you can adjust the angle of your torso.

This allows for coordinated force generation from the hip, knee, and ankle joints.

Increase overall torque output.

In other words—

Regarding hip joint torque.

When starting with straight arms, excessive forward lean of the torso results in a hip joint flexion angle of ≤90°. The hip joint's "hip extension torque," the torque that propels the torso backward, needs to overcome the excessive torso's gravitational torque. The torque value is only 120-130 N·m, which cannot fully utilize the gluteus maximus's power advantage, since the gluteus maximus is the main muscle that generates the hip extension torque.

If Bolt uses a bent-arm start, he can increase his torso angle to 45°-50° and his hip flexion angle to 110°-115°.

At this point, the torque of the torso will decrease, and the torque of hip extension will increase to 160-170 N·m.

in summary.

It can improve performance by 23%-41% compared to straight arm.

This allows the gluteus maximus to fully unleash its power potential.

Regarding knee joint torque, when starting with straight arms, the knee joint bending angle is ≤125°. The knee joint "extension torque," the torque that propels the lower leg to extend, may be overcompensated by insufficient hip joint torque, with a torque value of 180-190 N·m, far exceeding the safe force range of the knee joint.

It can easily lead to injuries such as patellar tendinitis.

This is especially true for Bolt, who is getting older.

Not a good thing.

When starting with bent arms, the increased torque at the hip joint can lead to a coordinated increase in the torque at the knee joint.

The knee flexion angle should be adjusted to 135°-140°.

Increase the knee extension torque to 200-210 N·m, which will put it within the upper limit of the safe range.

At the same time, the difference between the peak time of torque output and the peak time of hip joint torque is reduced from 0.03 seconds in straight arm mode to 0.01 seconds.

Achieve coordinated hip-knee force.

This will increase Bolt's overall lower limb torque output by 15%-20%.

Regarding ankle joint torque, when starting with straight arms, the ankle joint flexion angle is ≤30°, and the ankle joint "extension torque," the torque that propels the foot to push off the ground, is suppressed due to excessive compensation of the knee joint, with a torque value of only 80-90 N·m.

If you use a bent-arm start, Bolt can use his hip and knee to work together to fully extend his ankle joint.

The ankle flexion angle increases to 40°-45°.

The ankle extension torque increases to 110-120 N·m.

It will improve performance by 22%-50% compared to straight arm.

This allows Bolt to fully utilize the power advantage of his calf muscles.

In other words, as long as Bolt does this, the time difference between the peak torques of the three joints of the hip, knee, and ankle during the bent-arm start can be controlled within the ideal range of 0.01-0.02 seconds.

Avoid excessive 0.03-0.05 seconds when using a straight arm.

A 50%-80% improvement in synergy is a significant leap.

This effectively avoids "overloading of a single joint".

Improve overall efficiency.

It's just a pity.

Can't do it...

Mills had already come up with the general idea, but he always felt that the specific details were lacking.

Some steps were omitted.

Some precise data is missing.

This makes it impossible to fully attribute the name to Bolt.

He had Bolt try it once, but it didn't work well.

Then something must be missing.

This technology is currently unique to Ersha Island and cannot be made public. This is actually quite normal, just like some classic core and key papers are not published at the time.

This is true in any field.

If you want to break through, then you should do your own research.

After all, this is not the day when humanity will become a community with a shared future.

It has not yet achieved universal harmony.

It's impossible to be completely free from situations where people cherish their own possessions.

Having exhausted all other options, and with Bolt agreeing to the request from the American lab, Mills finally sent his research data and ideas to them, requesting their assistance in conducting joint research.

Don't say it yet.

This is where America surpasses Jamaica by a great margin.

Nothing else.

It's his technological prowess.

It's an absolute crushing victory.

They immediately gave feedback.

To achieve dynamic balance of joint torques, changes in trunk joint torques are required.

We need to move from "compensatory stress" to "stable transmission".

The idea proposed by the laboratory in the United States is that trunk joint torque, mainly including lumbar and thoracic spine torque, is the key to connecting the energy transfer between the upper and lower limbs. In Bolt's straight-arm start, the trunk torque of tall athletes naturally exhibits the characteristics of "tension compensation". However, if the start is with bent arms, the trunk can be adjusted from "passive support" to "active transmission" by adjusting the trunk posture and muscle activation mode.

Significantly reduces torque loss.

They offered several suggestions—

Firstly, from the perspective of lumbar spine torque, tall athletes need to maintain a low torso posture with an angle of 30°-35° with the ground when starting with straight arms. Bolt's lumbar spine is prone to being in an excessively flexed state. In order to balance the "flexion torque" generated by the weight of the torso, the erector spinae muscles in the lower back need to continuously output a high load "extension torque", with a torque value of 75-85 N·m. Moreover, the direction of the torque deviates from the "upward transmission torque" generated by the lower limbs pushing off the ground by 15°-20°, resulting in an energy transfer loss rate of 18%-22% in the lumbar spine.

Laboratory electromyography data showed that the continuous activation time of the erector spinae muscles in the starting phase accounted for more than 90% of the total duration, which could easily lead to the risk of muscle spasms.

If the position is in preparation, the angle between the torso and the ground is raised to 45°-50°, the degree of lumbar flexion will be significantly reduced, and the lumbar extension torque will drop to 45-55 N·m, which is only 60%-73% of that when the arm is straight.

Meanwhile, the bent-arm posture reduces the deviation between the trunk midline and the direction of the lower limb push-off to 5°-8°, the direction of the lumbar spine torque is highly consistent with the energy conduction path, the energy transfer loss rate is reduced to 8%-12%, and electromyography monitoring shows that the proportion of erector spinae muscle activation time is reduced to 65%-70%.

This significantly slows down the rate of muscle fatigue.

Secondly, regarding the torque of the thoracic spine, the "forward pulling torque" generated by Bolt's straight-arm start will cause excessive extension of the thoracic spine. In order to maintain the overall stability of the trunk, the pectoralis major and rectus abdominis muscles need to work together to output "forward flexion compensatory torque", with a torque value of 50-60 N·m. This "reverse torque counteraction" will further sever the energy transmission link between the upper and lower limbs.

This increases the energy loss rate at the thoracic spine by 5%-8%.

By changing to elbow flexion, the lever arm of the upper limb can be shortened, reducing the forward pulling torque on Bolt's thoracic spine to 25-35 N·m, and reducing the compensatory torque requirements of the pectoralis major and rectus abdominis muscles by 40%-50%.

At this point, using a bent-arm posture to retract the scapula will allow the thoracic spine to be in a "neutral position" with slight extension.

This creates a "coordinated transmission channel" between the thoracic and lumbar vertebral torque directions.

The "series transmission efficiency" of energy from the upper and lower limbs in the trunk can be increased from 65%-70% when the arm is straight to 85%-90%.

They provided an analysis of the torque transmission path in biomechanical modeling—

For Bolt to successfully start with his arms bent, the "transmission consistency coefficient" of the overall torque of the torso, the matching degree of the torque of the upper and lower limbs in the torso segment, needs to reach 0.85-0.90.

It far exceeds the 0.60-0.65 of a straight-arm start.

Once the trunk's function as the "energy conduction center" is fully activated, it can lay a stable foundation for the force conversion in the subsequent acceleration phase.

Torque at trunk joints?

Yes.

Mills felt as if someone had suddenly awakened his inner core.

Suddenly, inspiration struck.

The problem was actually caused by torque in the thoracic and lumbar vertebrae.

Why didn't I think of that?
in fact.

It wasn't that he hadn't thought of it, but given Jamaica's level of experimental technology and sports research, it was simply impossible to delve into this aspect.

Compared to the relatively simple muscle components, and the three-joint torque that has been studied for many years.

These two examples are closer to the deep muscles of a person.

In other words, it is difficult for ordinary equipment to penetrate this area.

It's simply impossible to perform a test with that level of precision.

Naturally, accurate data cannot be obtained.

It is impossible to make an accurate judgment.

But this.

With the experience and advice provided by Mills...

The labs in the US quickly found a breakthrough.

This way.

By reconstructing the force transmission path, we can go from "multi-node loss" to "linear efficiency".

This is crucial for Bolt's starting phase.

Because the integrity and linearity of force transmission directly determine energy conversion efficiency, in Bolt's straight-arm start, tall athletes have a "multi-node offset" problem in force transmission due to their special limb proportions. Only by adopting a bent-arm start can the linear force path of "lower limb push-off - trunk conduction - upper limb assistance" be constructed by reconstructing the support point and adjusting the joint angle, which can greatly reduce the natural starting energy loss caused by huge height and weight.

He made it very clear to Bolt and Mills.

Judging from the starting point of Bolt's starting force line, when Bolt starts with a straight arm, the knee joint of tall athletes bears excessive load, causing the force line to shift towards the inside of the knee joint when it is transmitted upward from the ankle joint.

The offset is 8-12mm.

This results in a "knee-inward" type of force line deviation.

This causes 10%-15% of Bolt's push-off energy to be converted into lateral torque at the knee joint, preventing it from contributing to forward propulsion.

Only by balancing the load on the lower limb joints and reducing the force distribution on the knee joint to 40%-45% can the force line be transmitted vertically upward from the ankle joint along the midline of the lower limb, keeping the offset within 3-5mm.

In this way, the "linearity coefficient" of the lower limb force line, the degree of coincidence between the force line and the lower limb midline, can be increased from 0.75-0.80 when the arm is straight to 0.92-0.95.

This increases the effective utilization rate of Bolt's push-off energy by 12%-18%.

In the middle transmission segment of the force line, that is, the trunk segment, the deviation of the torque direction between the lumbar and thoracic vertebrae when Bolt starts with straight arms will cause the force line to be transmitted in a "zigzag manner", resulting in a loss rate of 15%-20% of the starting energy at the lumbar-thoracic connection.

The only way to change this is to have Bolt maintain a "slightly extended-neutral" posture, reducing the deviation of the torque direction between the lumbar and thoracic vertebrae to 5°-8°, and transmitting the force line in a "straight line" along the central axis of the torso.

In this way, the "continuous transmission efficiency" of the force line in the torso segment can be increased from 70%-75% when the arm is straight to 88%-92%.

Laboratory motion capture data shows that when Bolt starts running with his arms bent, the difference in the force transmission velocity between any two points on the central axis of his torso is ≤0.02m/s.

Compared to straight boom, it reaches 0.05-0.07 m/s.

The synchronicity of force line transmission is significantly improved.

Then, after stabilizing the thoracic and lumbar vertebrae.

At the end of the force line, that is, the upper limb end, when Bolt starts with a straight arm, the upper limb needs to undertake the "active support-push-off" function. After the force line is transmitted from the torso to the upper limb, it needs to turn to the ground, with an angle of ≥30° with the forward direction. This will cause 5%-8% of the energy to be used for the upper limb push-off action and cannot be converted into forward kinetic energy.

At this time, when starting with bent arms, the upper limbs will switch to a "passive transition" function, so that after the force line is transmitted to the upper limbs, it only needs to maintain the body balance, and the angle between the direction and the forward direction is ≤10°.

In this way, the energy loss rate of the upper limb segment will be reduced to 1%-3%.

This allows more energy to be concentrated on pushing off the ground with the lower limbs for propulsion.

In this case.

A comprehensive quantitative analysis of force line transmission shows that if Bolt adopts the "total force line loss rate" during a bent-arm start, the sum of energy losses in each stage accounts for only 18%-22% of the total energy of the push-off.

And the percentage of runners who start with straight arms reaches 35%-40%!

That means the efficiency of force transmission can be improved by 40%-50%!

This is also one of the core reasons why Bolt's vertical support reaction force at the moment of pushing off the ground increased from 2.8 times his body weight to 3.2 times his body weight.

Lausanne stadium.

Bolt looked at Suarez's expression with satisfaction.

Honestly, he hadn't enjoyed that expression in far too long.

It seems that they have become increasingly rare since 2011.

But before 2011.

Such an expression.

It is not uncommon.

But even all of the previous experiences combined don't compare to the experience Su Shen has now.

After all, Su Shen had witnessed all those previous events.

And this is it now.

This is the first time in history.

"Su, just watch closely."

"Your craftsmanship."

"I can do that too."

Su Shen looked at Bolt.

It's rare for me to be stunned for so long after the restart.

I kept hearing the electronic commands coming from the loudspeaker behind me.

He had just come to his senses.

He realized that Bolt would improve in certain areas.

But he didn't expect that Bolt would master the bicep start before retiring.

That would mean deviating from one's original ideas.

What consequences will occur?
He doesn't know anymore.

"set".

Mills was also watching from the sidelines at that moment.

He was still in the stands.

Because he said he didn't like watching from the sidelines.

And this time.

Mills was also muttering to himself.

Let everyone take a look.

The first curved-arm start not on Ersha Island.

Just how amazing is it?

Yussane.

Arms display.

Please begin.

……

BOOM ————————————

The others were also somewhat stunned by the starting posture that Bolt displayed.

Including Ersha Island.

You should even know that Yu Weili's mind immediately raced with many thoughts. He glanced at Yuan Guoqiang beside him, and the two of them had the same idea—

Could there be a mole within the organization?

Otherwise, how did they learn it?
Information on this topic.

Su Shen.

But it has never been made public.

It has always been a unique feature of Ersha Island.

Now it has suddenly appeared in Bolt.

That makes things more complicated.

It's a bit too big.

Especially at the Bird's Nest, which is just around the corner.

will not.

What other unexpected events might occur?

Why is it that every time our country's top track and field athletes have to compete at home?
There will always be some kind of obstacle.

This is what Liu Xiang looked like in 08.

Because Robles suddenly broke his world record.

This caused the entire team to become extremely tense.

The previous sense of relaxation has been lost.

The intensity and density of training also increased unconsciously.

Otherwise, it's hard to say whether they could have made it through the 08 Olympics. But there's no time for them to think about that now, because the starting gun has already been fired.

Did Usain Bolt actually use a bent-arm start?

Or is it just for show?
The answer will be revealed soon.

Bolt's mind is currently focused solely on those key parameters—

Adaptive adjustment of key joint angles.

When tall athletes start with straight arms, their hip joints (≤90°) and knee joints (≤125°) are excessively bent, which causes the joints to be in a "non-optimal force-generating angle," and the muscle power output is only 65%-70% of the maximum force.

To achieve the optimal power angle, you need to start with your arms bent to adjust the hip joint angle to 110°-115°.

The knee joint angle should be adjusted to 135°-140°.

Adjust the ankle joint angle to 40°-45°.

This ensures that all three major lower limb joints are within the peak range of the "force-angle relationship curve".

This allows muscles to output 85%-90% of their maximum strength.

The adaptability of joint angles is improved by 30%-38%.

Then comes the smooth shift of the body's center of gravity.

When you start running with your arms straight, the vertical displacement of your center of gravity from "ready" to "take off" is 0.35-0.40m, while the horizontal displacement is only 0.20-0.25m. The movement of your center of gravity exhibits an "up and down" characteristic, which will consume an extra 10%-12% of energy.

To avoid this, when using a bent-arm start, you should reduce the vertical displacement of your center of gravity to 0.20-0.25m.

The horizontal displacement was increased to 0.30-0.35m.

The trajectory of the center of gravity movement is closer to "forward translation".

In this case.

Energy waste can be reduced by 60%-70%.

Motion capture data during training.

By doing this, the ratio of horizontal displacement to total displacement during a bent-arm start can reach 0.65-0.70.

Compared to a straight arm, it is only 0.40-0.45.

The efficiency of focusing on advancement has been significantly optimized.

Finally, there is the precise coordination of action timing before the start of the break.

When starting with straight arms, the time difference between the upper and lower limbs exerting force can reach 0.05 seconds, which can cause a disconnect between the "lower limbs pushing off the ground and the upper limbs pushing off" movements.

Mastering the bent-arm start is essentially simplifying upper limb movements.

This reduces the time difference between upper and lower limb exertion to 0.01-0.02 seconds.
The "coordination coefficient" of the "push-swing" action sequence, the matching degree of the start time of the upper and lower limb movements, can be improved from 0.60-0.65 when the arm is straight to 0.90-0.95.

At the same time, the bent-arm start makes the time allocation of each stage of the start, from preparation to push-off to acceleration, more reasonable.

The proportion of the "push-off phase" has increased from 30%-35% when the arm is straight to 40%-45%.

It can provide a longer window of opportunity for your lower limbs to exert full force.

So many years.

They lost from London in 12 all the way to Moscow in 13.

until now.

It's been three or four years already.

Bolt is somewhat overshadowed by Suarez.

Now even world records have been broken.

If he can't come up with something else...

Then he would be completely suppressed.

There is no chance of turning things around.

So Bolt has been playing at full capacity for the past two years.

He could even say that he has lived his whole life.

I wasn't that serious.

in order.

It means defeating this Asian man next to you.

This was more than any opponent he had ever encountered in his life.

They all want to defeat them.

Bolt's body first entered a "static charging" state.

The details of the movement and muscle activity at this point demonstrate the adaptability of the flexed arm technique to tall body structures.

His feet were positioned on the front and rear starting blocks respectively, with the balls of his feet fully pressed against the front step and the heel of his rear foot slightly raised, only the outer edge of the forefoot touching the rear step. The distance between his feet was approximately 1.2 times his shoulder width.

This width is precisely calculated to avoid the dispersion of hip joint torque caused by excessive abduction of the lower limbs, and to reserve enough space for the coordinated "hip-knee-ankle" force exertion during subsequent push-off.

The posture of the upper body is the core manifestation of the bent-arm technique: the torso is not excessively low like in the traditional straight-arm start, but maintains an angle of 45°-50° with the ground, the shoulder line is slightly higher than the hip, the cervical spine is naturally flexed forward, and the eyes are looking straight ahead at the ground 1.5 meters away, avoiding lumbar compensation caused by excessive backward tilting of the head.

More importantly, the upper limb movements are as follows: the elbow joint is noticeably bent, the angle between the upper arm and forearm is stable at about 95°, and the top of the elbow joint is about 15-20cm from the ground, which is 8-10cm higher than when starting with straight arms.

The shoulder joint angle should be adjusted to 130°-140°.

The scapula retracts downwards and backwards, bringing the upper arm close to the sides of the torso, rather than extending and abducting forward as in the case of a straight arm.

This posture directly alters the force distribution pattern of the upper limb muscles.

From a muscular perspective, Bolt is currently building a stable support system through "multi-muscle group graded pre-activation." In the upper limbs, the biceps brachii and brachioradialis muscles are the first to enter a state of tension, with the muscle fibers showing a slight shortening trend, bearing the main load of the elbow flexion torque.

Because the elbow joint is bent, the direction of the torque generated by the supporting reaction force changes from the "elbow extension torque" when the arm is straight to the "elbow flexion torque". The triceps brachii, which originally needs to exert continuous force, can relax and only maintain 10%-15% of the basic tension to avoid excessive bending of the elbow joint.

At the same time, the middle deltoid is in a moderately activated state, with electromyography (EMG) showing an integrated EMG value of approximately 45 μV·s. It generates an adduction torque through slight contraction, fixing the shoulder joint in a neutral position of 130°-140°. This prevents muscle tension caused by excessive load on the posterior deltoid due to the "extension torque" when the arm is straight. At this time, the supraspinatus and infraspinatus muscles around the shoulder joint are also activated simultaneously, forming a "dynamic stability ring" to prevent force line deviation caused by scapular anterior tilt.

The pre-activation of the lower limb muscles revolves around "torque reserve." The gluteus maximus, as the core muscle group generating hip extension torque, is already 20%-25% activated at this point, with its muscle fibers exhibiting a slow stretching tendency, storing elastic potential energy like a compressed spring.

With the trunk angle increased to 45°-50° and the hip flexion angle reaching 110°-115°, compared to ≤90° when the arm is straight, the gluteus maximus does not need to resist excessive trunk gravitational torque and can complete pre-charge by maintaining basic tension. Electromyography monitoring shows that its IEMG value is about 60μV·s, which is much lower than 85μV·s when starting with a straight arm.

The quadriceps, especially the rectus femoris and vastus lateralis, are activated simultaneously, and the muscle fibers are in a "stretched-tense" state, fixing the knee joint at the optimal force-generating angle of 135°-140°. At this time, the knee extension torque has been initially established, laying the foundation for the explosive torque during subsequent push-off.

Bolt's calf muscles, including the gastrocnemius and soleus, maintain a 15%-20% activation level, with an ankle flexion angle of 40°-45° and the sole of the foot slightly pressed down, allowing the plantar fascia and muscle fibers to enter a "pre-stretched" state in advance, thus avoiding delayed push-off due to delayed muscle activation after the starting gun.

The operation of the back muscles demonstrates how the bent-arm technique optimizes trunk stability. Due to the increased trunk angle, the erector spinae muscles do not need to continuously output high-load extension torque as they do when starting with a straight arm. They only need to maintain 30%-35% activation to balance the flexion torque generated by trunk gravity. The muscle fibers exhibit a uniform tension state, rather than the "localized spastic compensation" seen with a straight arm.

Slight contraction of the rectus abdominis and external oblique muscles generates a moderate flexion torque, creating an "antagonistic balance" with the erector spinae muscles to fix the lumbar spine in a neutral position.

At this time, the extension torque of the lumbar spine is only 45-55 N·m.

It is 40% lower than when he has his arm straight.

It effectively prevents excessive fatigue of the lower back muscles.

Alright, all work is ready.

We're just waiting for the gun to fire.

It has been shown to the whole world.

He hadn't used it before.

That's why we've been waiting until now.

They were just waiting for this moment to face Su Shen face-to-face.

Should I make it for him myself?

The entire "preparation" phase lasts about 2-3 seconds. Bolt's body functions like a precisely calibrated mechanical system, adjusting the angles of his joints through bent-arm support, ensuring that the main muscle groups are in a "low-load pre-activation" state.

This avoids energy consumption caused by premature high-intensity contraction and ensures that he can quickly enter the explosive state after the gun fires, at which point his body center of gravity is directly above the midpoint of the line connecting the two starting blocks.

It is about 0.55-0.60m above the ground.

The center of gravity height is increased by 0.10-0.15m compared to the straight-arm start.

By shortening the upper limb lever arm through bending and shortening it, and by maintaining a balanced lower limb torque, greater support stability is achieved.

This perfectly sets the stage for the subsequent explosive push-off.

The gunshot rang out.

Bolt jumped up in response.

Immediately after the gunshot, Bolt's lower limbs were the first to move. The gluteus maximus, as the core source of hip extension torque, instantly jumped from 35% pre-activation to 90%. The muscle fibers contracted rapidly at a frequency of 12-15 times per second, and the resulting hip extension torque soared from 160 N·m to 280 N·m.

The hip flexion angle is maintained at 110°-115°, which is in the peak range of the gluteus maximus's "force-angle relationship curve". The output efficiency of muscle power is over 90%, which is much higher than the 65% efficiency caused by excessive hip flexion when Bolt starts with straight arms.

A strong contraction of the gluteus maximus leads to rapid hip extension.

Rotate the torso counterclockwise around the hip joint.

The angle between the torso and the ground rapidly increased from 45° to 60°.

At this moment, Bolt's erector spinae muscles in his lower back simultaneously increased in activation to 60%.

Stabilize the lumbar spine with appropriate extension torque.

Avoid excessive extension of the torso that could cause a shift in the force line.

The energy loss rate in the lumbar spine has been greatly reduced compared to before.

Gluteus maximus activation.

work hard.

shrink.

Almost simultaneously with the activation of Bolt's gluteus maximus, his quadriceps also entered a "peak activation state," with the activation level instantly exceeding 95%.

With the knee joint bending angle at 140°, the quadriceps muscle spindle is fully stretched and then quickly released, with an elastic potential energy conversion efficiency of 85%, which drives Bolt's lower leg to quickly push forward and downward, increasing the knee joint angle from 140° to 170° in 0.05 seconds.

During this process, the force on Bolt's knee joint was precisely controlled at 40%-45%, avoiding the excessive load of 55%-60% that occurred during the previous straight-arm start.

The tension on the patellar tendon decreased from 3.0 times body weight to 2.7 times body weight.

It has completely broken free from the predicament of "sole dominance of the knee joint" in terms of force exertion.

This is followed by the coordinated action of the calf muscles and the tibialis anterior.

The activation level of the calf muscles increased from 40% to 92% within 0.03 seconds.

The soleus muscle, with a higher proportion of slow-twitch muscle fibers, is the first to generate the basic ankle extension torque through isometric contraction.

Subsequently, a large number of fast-twitch fibers of the gastrocnemius muscle are involved, causing the ankle extension torque to explode from 100 N·m to 220 N·m, which drives the ankle joint to quickly extend from a 42° flexed state to 175°, and the forefoot generates a strong push-off force against the starting block pedal.

At this point, Bolt's vertical support reaction force reached 3.2 times his body weight, a 14% increase from 2.8 times his body weight when starting with straight arms, and the peak time was earlier, reaching 0.08 seconds, which is basically the same as that of athletes of normal height.

It significantly solves the problem of delayed peak vertical reaction force for tall athletes like Bolt.

Push off with your foot.

hum-

During Bolt's leg push-off, the time difference between the peak torque of the hip-knee-ankle joints was controlled within 0.01-0.02 seconds.

The peak torque of the hip joint occurs at 0.04 seconds after the gunshot, the peak torque of the knee joint occurs at 0.05 seconds, and the peak torque of the ankle joint occurs at 0.06 seconds.

This "step-like burst" forms a continuous torque transmission chain, allowing Bolt's ground-pushing energy to accumulate like waves, rather than the "discontinuous force" of his previous straight-arm start.

At this time, the contraction pattern of the lower limb muscles exhibits the characteristic of "concentric contraction as the main form and eccentric contraction as the secondary form"—

Bolt's gluteus maximus, quadriceps femoris, and triceps surae all generate active force through concentric contraction, while the adductor muscles on the inner thigh and the hamstrings around the knee joint contract at an eccentric rate of 15%-20%.

This is to prevent injuries caused by overextension of the joint.

This forms a dual mechanism of "exertion and protection".

Unlike the explosive power of his lower limbs, Bolt's upper limbs maintained a "passive support-rapid transition" function at the moment the gun fired.

The bent-arm posture completely changed the force distribution pattern of his upper limbs during a straight-arm start.

This allows the upper limbs to shift from "actively pushing away" to "assisted stabilization".

It significantly reduces energy consumption and torque conversion losses.

When the reaction force generated by the lower limbs pushing off the ground propels the body forward and upward, the supporting function of the upper limbs quickly transitions to "push-off assistance"—

Bolt's palms shifted from a "completely closed" position to a "finger-tip-first" position, and his forearms slowly prolapsed under the slight action of the pronator teres muscle, causing his palms to shift from vertical support to a slight tilt, reducing the ground friction when pushing off.

During this process, the activation rate of the upper limb muscles was consistently kept below 60%, far lower than the 90% of the lower limb muscles!

The energy consumption is only 80% of that of a straight-arm start.

This allows more energy to be concentrated on pushing off the ground with the lower limbs.

boom.

The first step is pushing off the ground: a rapid secondary exertion of force by the lower limb muscles.

When Bolt lands on his first step, the ball of his foot, which is originally the supporting foot of the starting block, makes contact with the ground first. The contact point is located 15-20cm in front of the projection of his body's center of gravity, and the ball of his foot forms a forward lean angle of 15°-18° with the ground.

This angled design can both cushion the ground reaction force through the elastic deformation of the forefoot and quickly convert it into pushing power. At the moment of landing, the calf muscles first enter an eccentric contraction state, with muscle fibers slowly elongating at a speed of 0.2m/s to absorb the energy generated by the ground impact. The IEMG value briefly rises to 70μV·s, preventing excessive bending of the ankle joint due to sudden force.

At the same time, the tibialis anterior muscle is activated, maintaining foot stability through concentric contraction and preventing the risk of tripping caused by excessive toe drop.

Thus.

This looks like a memorable scene from the World Championships in Beijing.

It may not happen.

Subsequently, the lower limbs quickly transitioned from "buffering" to "pushing off the ground".

Connect the four points.

The gluteus maximus bursts with energy again, increasing its activation level from 60% to 85%. Through concentric contraction, it generates a powerful hip extension torque, driving the hip joint to quickly extend from a 130° flexion to 170°, causing the thigh to swing backward and upward, providing the body with the main forward momentum.

At this point, the quadriceps are not fully relaxed, but maintain 40%-45% activation, assisting knee extension through moderate concentric contraction to avoid knee compensation caused by excessive hip joint exertion.

Unlike the straight-arm start, the bent-arm technique provides stable trunk transmission, allowing the knee joint to still bear about 40% of the force.

In other words, there was no overload situation.

Despite its massive size and aggressive startup mode, it didn't experience excessive strain.

Isn't this exactly what Mills wanted?
Starting from the second step, Bolt's start enters the "start-up strengthening" phase, with his body posture and muscle operation gradually transitioning to acceleration.

boom.

When landing in the second step.

The angle between the trunk and the ground further increases to 75°, and the activation rate of the erector spinae muscles decreases from 60% to 50%, but still maintains sufficient tension to stabilize the lumbar spine. At this time, the energy transfer loss rate of the trunk has decreased to 6%-8%, and the energy generated by the lower limbs pushing off the ground is transferred to the whole body with almost no loss.

Bang bang bang.

Steps three through five are the key stages for speed improvement.

Bolt's lower limb muscles began to exhibit a contraction pattern dominated by fast-twitch fibers—the activation rate of fast-twitch fibers in the gluteus maximus, quadriceps femoris, and triceps surae increased from 60% to 75%, the muscle contraction speed further accelerated, and the push-off time shortened from 0.12 seconds to 0.10 seconds.

At the same time, the activation rate of the hamstrings increased from 20% to 30%, assisting in knee joint stability through moderate eccentric contraction.

The adductor muscles on the inner thigh maintain the stability of the lower limb's force line with 25% activation, preventing the loss of force caused by knee valgus.

The activation level of the anterior and posterior deltoids remains at 70%-75%, the arm swing trajectory is closer to the torso, and the effective propulsion force accounts for more than 95%.

The activation levels of the biceps and triceps are dynamically adjusted according to the arm swing position. The activation level of the biceps increases during the forward swing and the activation level of the triceps increases during the backward swing, ensuring that each arm swing movement has sufficient muscle strength support.

bang bang.

The last two steps of the startup phase.

Bolt's body has basically completed the transition from the start to the middle of the race. The angle between his torso and the ground has increased to 80°-85°, close to the acceleration posture. The activation of the erector spinae muscles has dropped to 40%, only maintaining basic trunk stability.

In terms of the lower limbs, the push-off pattern changes from "mainly back push-off" to "a combination of front and back push-offs". The activation rate of the gluteus maximus decreases to 70%, while the activation rate of the quadriceps increases to 60%, propelling the body forward through a stronger knee extension torque.

Although the activation rate of the calf muscles drops to 80%, the contraction efficiency is higher, and the extension speed of the ankle joint increases by 10%, making the transmission of the push-off reaction force faster.

The goal of "rapid start-efficient acceleration" brought about by the articulated start technique has been largely achieved.

Throughout the entire 10-meter, 7-step starting process.

Bolt's muscle work is always characterized by "coordination and efficiency".

The coordinated torque of the three joints of the lower limbs (hip, knee, and ankle), the functional adaptation of the upper limbs (arm swing and support), and the seamless connection of the trunk (stability and transmission) together construct a starting system specifically for tall athletes.

It's equivalent to saying.

The bent-arm posture not only solves the three major contradictions of center of gravity, torque, and energy transfer for tall people.

Furthermore, it achieves precise muscle activation control and optimized movement timing.

Transforming biomechanical principles into practical technical details.

This wave of technical changes.

It came solidly.

It's all baseless rumor.

Each step is supported by detailed scientific principles, scientific data, and technological allocations.

In practical terms, that's what happens.

Bolt here.

It's definitely not as terrifying as Su Shen's activation.

but.

This was definitely the fastest shot he ever fired in his life.

In the past, Su Shen could leave him about two meters behind when he started.

This time.

No more.

There's only a little over a meter between them now.

correct.

Bolt's initiation reaction.

They're all here.

He reached his peak since the Daegu World Championships.

The largest value.

0.131.

Perhaps compared to those with superhuman reflexes, he's just at a passable level.

But for Bolt...

The curse of mindset.

It's as if he crushed it with his own hands.

So this shot.

It's terrifyingly strong.

How strong is it?
Except for that bright red figure.

Start-up expert.

Powell.

Gatling gun.

Everything was suppressed.

Not to mention Guy Blake and others.

In contrast, Zhao Haohuan, who is also tall and starts with bent arms, is a better example.

The gap widened immediately.

Even Carter was watching the game on TV.

After watching it, I felt completely bewildered.

He even felt.

Even when you've pushed yourself beyond your limits.

He completed the modification of the Su Shen system's skills.

Both are on the startup side.

You won't gain much advantage.

even.

They might also lose to this giant that's over 1.95 meters tall.

This……

This game.

It's probably going to explode.

That's almost true.

All experts, please read this.

I only looked at it for ten meters.

The conclusion that can be drawn is...

Usain Bolt.

Start with bent arms.

On this magical track in Lausanne.

I started my own thing.

The first wave.

Arms display.