The Su God of the Reopening of the Sports Arena

Chapter 2153: Stand back! Let me show you

Hayward Live.

Carter showed off his strong start.

Bolt.

Not much less.

Or.

This guy's brain.

There is no concept of "let".

During the static squat phase, the forefoot bears a static load of approximately 60% of the body weight.

From the perspective of the human kinetic chain, this load distribution is closely related to the human anatomical structure and muscle function.

The forefoot connects to the front calf muscles and small foot muscles that play an important role in maintaining body posture and providing initial support.

Because the body's center of gravity leans forward when sprinting starts, the forefoot, as the front support point, needs to bear a greater load to maintain body balance.

From the perspective of mechanical principles, this load distribution places the body's center of gravity in a relatively stable area, laying the foundation for subsequent starting movements.

According to the principle of moment balance——

The torque generated by the body's gravity needs to be balanced by the counter-torque generated by the supporting force of the forefoot and the rear foot. The forefoot bearing a larger load helps reduce the torque generated by the supporting force of the rear foot, making it easier to maintain a stable posture of the body during the static squat phase.

Why say this?

That's because... that's what Bolt is doing now.

It was also Mills who told him that it was called the bipedal pressure center migration trajectory.

For example, the pressure center of the rear foot moves backward during starting.

That is, the pressure center of the hindfoot moves 2 - 3cm posteriorly along the sagittal plane.

This phenomenon has a deep neuromuscular control and mechanical logic.

It's not a random thing.

Mills is definitely a man of quality.

During the transition from squat to start, the neuromuscular system makes subtle adjustments to the body's posture.

The posterior shift of the rear foot center of pressure is due to the pre-activation and contraction preparation of the posterior calf muscles, such as the triceps surae.

Contraction of these muscles pushes the hindfoot backward and downward, causing the center of pressure to shift posteriorly.

From the perspective of sports mechanics, the rearward shift of the rear foot pressure center changes the line of action of the rear foot support force.

This changes the direction of the torque generated by the rear foot support force.

This helps provide a backward and downward push at the moment of departure.

Provides high-quality reaction force for the body to accelerate forward.

Additionally, this backward shift also adjusts the shape and size of the body's overall support surface.

This is equivalent to further optimizing the body's balance state before starting, which in turn improves the stability of starting.

Of course, Bolt didn't understand these things.

He doesn't need to understand.

Mills just understands.

When the reaction time reaches the threshold of 180-220ms, the peak pressure can reach 3.5 times the body weight in the forefoot and 2.8BW in the hindfoot.

This is because at the moment of starting, the neuromuscular system is rapidly activated and the muscles produce a strong contraction.

The peak pressure in the forefoot mainly comes from the explosive contraction of the anterior calf muscles and foot extensors. These muscles generate huge force in a short period of time, pushing the forefoot down to press the starting block.

The peak pressure of the hindfoot is mainly caused by the strong contraction of the posterior calf muscles, especially the triceps surae.

According to the mechanical principles of muscle contraction, muscles can generate greater force when they contract rapidly than when they contract statically.

Then, at the critical moment of starting a sprint, the rapid contraction of these muscles can cause the pressure of the feet on the starting blocks to increase sharply, forming a pressure peak.

And then…the pressure gradient difference enters and forms a propulsion couple.

This is the key mechanism for generating forward propulsion during a sprint start.

Because the peak pressures in the forefoot and hindfoot are different for each person, a pressure gradient is formed along the sagittal plane.

According to the mechanical definition of a couple, a couple is a force system composed of two forces of equal magnitude, opposite direction and non-collinear, and its effect is to cause an object to rotate.

During the start of a sprint, the greater pressure on the front foot and the relatively smaller pressure on the rear foot form a force couple, which has the effect of rotating the body forward around a horizontal axis, thereby generating forward propulsion.

From the perspective of motion chain transmission, this propulsive force couple is transmitted upward to the trunk and upper limbs through the lower limb joints, including the ankle, knee and hip joints, driving the entire body to accelerate forward.

The subsequent formation of the propulsive force couple is also closely related to the coordinated control of the neuromuscular system over the extension of the two feet.

Only when the pushing force and timing of the two feet are precisely coordinated can an effective propulsive force couple be formed and an efficient sprint start be achieved.

Mills.

One of the start-up optimizations for Bolt's winter training this year.

This is what was arranged.

Then based on the principle of peak power output of the ankle joint.

Bolt's ankle joint generates a peak power output of about 2800W at the moment of pedaling off, a phenomenon that stems from the efficient work of the calf muscles.

The gastrocnemius and soleus muscles at the back of the calf are the main drivers of plantar flexion of the ankle joint.

During the push-off phase, these muscles contract rapidly, generating a powerful force to plantar flex the ankle.

At the moment of kicking off, the force generated by the contraction of the calf muscles reaches its peak, while the speed of ankle plantar flexion is also at a high level. The product of the two makes the power output reach the maximum value.

During muscle contraction, the cross-bridges between actin and myosin continually bind, dissociate, and recombine, a process that consumes energy and generates force.

In other words - when the muscle performs the cross-bridge cycle at a higher rate, it can generate greater force and accelerate the muscle shortening rate, thereby achieving high power output.

The key point is that Mills is improving the power output of Bolt's ankle joints!

After this winter training.

Before Bolt starts, his nervous system pre-activates the calf muscles and adjusts the initial state of the muscles, putting them in the best state of readiness for contraction.

When the starting signal is given, nerve impulses are quickly transmitted to the muscles, triggering synchronous muscle contraction.

This precise neural control ensures that muscles contract at the correct time and intensity, improving energy efficiency.

Good neuromuscular coordination can also enable muscles to recruit more motor units to participate in the work during contraction, further enhancing the muscle's contraction force and power output capacity.

Do you think this is over?

That would underestimate Mills' status as a super coach.

In Jamaica, a place where the level of technology is many years behind America, it can still cultivate such epoch-making super athletes.

More than one.

Of course I have real skills.

The above is just the beginning.

What comes next is the key point.

Only when the top is done well can the bottom be done well.

Bolt steps forward!

The knee extension torque reaches 3.1Nm/kg!

This is mainly caused by the contraction of the knee extensor muscles, including the quadriceps femoris, which include the rectus femoris, vastus medius, vastus lateralis and vastus medialis, which work together to extend the knee joint during activation.

The magnitude of the knee extension torque depends on the force generated by muscle contraction and the length of the moment arm.

During the start phase, the force generated by the contraction of the quadriceps is transmitted to the calf bone through the patellar tendon. The moment arm is the vertical distance from the center of the knee joint to the attachment point of the patellar tendon.

According to the torque calculation formula (torque = force × lever arm), Mills conducted many experiments and finally found the powerful contraction force of Bolt's quadriceps and the appropriate lever arm length!

This allows Bolt's knee joint to generate a larger extension torque when he starts.

Then strengthen other muscles and connective tissue around the knee joint.

This plays an auxiliary stabilizing and synergistic role.

Ensure smooth knee extension movement.

Through the principle of knee extension torque, muscle synergy and torque generation are achieved.

Then joint stability is used to improve the efficiency of starting the movement.

boom!

The large knee extension torque that Bolt generates in his first step not only helps propel his body forward, but is also crucial to maintaining knee stability.

This is because when sprinting starts, the body is subjected to greater ground reaction force and inertia force, and the knee joint needs to bear a great load.

The reinforcements Mills arranges can resist these external forces through a strong knee extension moment.

Prevents excessive knee flexion or injury.

The energy transfer efficiency of the lower limb kinetic chain is then improved through a stable knee joint.

This allows power to be transferred more efficiently from the hip joint to the ankle joint, thereby pushing the body forward and accelerating.

This is because - appropriate knee extension torque can adjust the movement trajectory of the lower limbs.

Keep your body in good posture when starting.

Reduce energy loss.

What Mills is dealing with here is really a chain of events.

Bolt probably doesn't understand anything.

but……

Mills understands it all.

The second step.

Through the relationship between hip joint angular velocity changes and muscle contraction, Bolt's Hill equation and muscle contraction characteristics are created.

Bolt's hip joint angular velocity accelerated from 0.2° to 85° in 155 seconds.

The Hill equation states that there is an inverse relationship between the force generated by a muscle contraction and the speed at which the muscle contracts.

During the acceleration of the hip joint, the muscles around the hip joint, such as the gluteus maximus and iliopsoas, play a major role.

When the muscle begins to contract, the muscle is able to generate a greater contraction force due to the low initial angular velocity of the hip joint.

Then as the angular velocity of the hip joint increases, the force of the muscle contraction gradually decreases, but… the contraction speed increases.

This force-velocity relationship, if handled properly, can enable the hip joint to achieve rapid acceleration in a short period of time.

Look at Bolt taking this step.

The gluteus maximus contracts with greater force.

Provides initial rotational momentum to the hip joint.

As the angular velocity of the hip joint increases.

Muscle contractions speed up.

Bolt then continued to push his hip joint to accelerate rotation.

This drives the lower limbs to swing rapidly.

The body accelerates and propels forward. Another step.

The rapid increase in angular velocity of the hip joint…means that a lot of energy is converted into rotational kinetic energy of the hip joint.

During this process, the muscles convert chemical energy into mechanical energy through contraction, providing power for the movement of the hip joint.

at the moment……

New and efficient energy conversion.

It is one of the key factors in Bolt's outstanding performance in the new season.

Mirsky attempted to use reasonable muscle contraction patterns and neural control to allow Bolt to put more energy into the acceleration of the hip joint in a short period of time.

This results in a faster startup speed.

Combined with the rapid rotation of the hip joint, it drives the coordinated movement of the entire lower limb movement chain.

Further improves the body's forward propulsion efficiency.

This is the new starting mode that Mills has created for Bolt.

Again.

Bolt himself may not know why he did this.

What is the reason for doing this.

can.

Mills knew enough.

Although Bolt's brain is not that good.

The specific principles and processes cannot be analyzed.

can.

He has a talent, which is that his body can quickly master the things that Mills arranges.

It’s okay if you don’t understand.

Strictly implement.

The brain doesn't understand the principle.

As long as the body can be made, it's fine.

But such talent is rare.

Most people don’t understand.

Your body is also difficult to fully understand.

Bolt is the typical "talented black athlete".

No need to know why.

As long as someone tells him what to do.

As long as Mills has excellent direction control.

Then Bolt can also...

Excellent work.

at this point.

It is also a talent point that Blake does not have.

boom.

Another step.

The four golden steps.

last step.

It is also the last kick Mills gave Bolt to start the optimization. Through the principle of hamstring eccentric-concentric contraction conversion efficiency, a stretching-shortening cycle mechanism is created.

The so-called stretch-shortening cycle mechanism is a muscle movement pattern, which refers to the process in which the muscle quickly enters concentric contraction after eccentric contraction, with a short transition phase in between.

For example, when jumping vertically, you first squat down to stretch your muscles and enter the eccentric phase, and then jump up with force to enter the concentric phase. This process embodies the SSC mechanism.

Why did Mills do this? The reason is——

During the eccentric phase, the muscle is stretched rapidly, like a spring being stretched, and the tendons and muscles store elastic energy.

The transition phase, also called the isometric phase, is a brief transition between eccentric and concentric movements during which the body needs to maintain stability to ensure smooth energy transfer.

During the concentric phase, the muscles contract rapidly, releasing the elastic potential energy previously stored.

This allows for greater bursts of power and better athletic performance.

For example, the four golden steps now.

At the start of Bolt's sprint.

The hamstrings undergo an eccentric contraction first.

During hip extension and knee flexion, the hamstrings are lengthened, storing elastic potential energy.

The hamstrings then rapidly contract concentrically, releasing the stored elastic potential energy while also generating contractile force on their own.

Then, the superposition of this elastic potential energy and the active contraction force of the muscles enables the hamstrings to produce greater force and power output during the concentric contraction phase.

This is Mills' final step in building Bolt's starting ability.

Utilize the SSC mechanism.

To improve Bolt's shortcomings.

effect.

Pretty obvious.

Even if Carter had a strong start in the front, he should have been ahead of the rest, and even Bolt should have been left far behind.

result.

Bolt was by Carter's side.

Not been...

How much to pull apart.

even.

The last of the four golden steps.

He wants it all.

Catch up???

what happened?

Carter was also a little confused.

Bolt is over 1.96 meters tall.

You told me that startup can be compared with myself.

Or compare yourself with yourself after completing the optimization this year?

It doesn't make sense.

Absolutely no sense!

This is impossible!

This is unreasonable!

but……

There is no such thing as reasonable or unreasonable.

Reality doesn't require logic.

Bolt.

Just start chasing Carter closely.

Start the master Carter.

During the startup phase.

Actually...

Take a person who is nearly two meters tall.

There's nothing we can do.

This was something Carter himself had never thought of.

No matter how it was before, I couldn’t run a hundred meters, I couldn’t run for the future, so I started…

Can you still outrun it?

just now.

Startup is caught up!

Carter felt a little bit upset too, and his head was turning white.

See it.

This is what I am capable of now.

Bolt is extremely confident.

His coach, Mills, also nodded slightly beside him, as if he was admiring the masterpiece he had created with his own hands.

but.

Have you forgotten something?

Carter is awesome. He has made a breakthrough this year and is reaching a new level.

Bolt is very good, and his start this year was even better, making up for his shortcomings and greatly improving his starting speed.

They are all awesome.

They all feel that they can do it.

Can……

This is in the eyes of another person.

Just want to say one thing -

Crooked, crooked.

Have you finished performing yet?

The performance is over.

Just step back.

It's my turn.