Bang bang bang bang bang bang.

The quadriceps femoris is the main muscle in the knee extension joint and plays a key role in the startup process.

When the knee joint is excessively flexed, the quadriceps femoris will enter a longer length state. In this case, centrifugal contraction, the cross-bridge connection and dissociation process within the muscle will be affected.

According to the gliding theory of muscle contraction, muscle contraction is achieved by the cross-bridge interaction between actin and myosin.

Excessive flexion causes the initial length of the muscle to be too long, and the formation and dissociation of the cross-bridge connections slow down, resulting in delayed centrifugal contraction of the quadriceps femoris.

This not only weakens the efficiency of the brake force converted to forward driving force at startup, but may also lead to an extended start-up reaction time.

Controlling the knee angle of the front leg at 105°-110° can keep the quadriceps femoris at a relatively appropriate initial length, ensuring that it can quickly and effectively perform centrifugal-centripe contraction conversion during startup.

The first level of preparation is prepared for the body to move forward.

Then there is the setting of the hind leg knee angle.

Carter's choice here is 130°-135°.

When the knee joint of the hind leg is in a reasonable range, muscles such as the calf triceps and the Achilles tendon are in a moderate stretching state.

According to the principle of elastic mechanics, an elastic potential energy will be stored when an elastic body is stretched, and the magnitude of the elastic potential energy it stores is related to the degree of stretching.

At this angle, the Achilles tendon is stretched to the appropriate level, which can maximize the reserve of elastic potential energy.

At the moment of starting the ground push, the Achilles tendon rebounds like a compressed spring, releasing stored elastic potential energy, assisting the calf muscles to contract and providing the body with additional forward propulsion force.

This utilization of elastic potential energy can effectively reduce the energy consumed by active contraction of muscles, and at the same time improve the output efficiency of ground-pushing force, allowing Carter to obtain faster speed and stronger explosive power when starting.

Let's take another step.

The dorsiflexion angle of the fore ankle joint is set to 25°±2°.

This mainly achieves "preloading" through precontraction of the plantar flexor muscle group.

The plantar flexor muscle groups include the calf triceps, etc. When the ankle joint is at this dorsiflexion angle, the plantar flexor muscle groups are stretched and pre-contracted.

From the perspective of neuromuscular control, precontraction can activate the muscle shuttle receptors in the muscles. The muscle shuttle transmits information about changes in muscle length and tension into the central nervous system, allowing the central nervous system to adjust and prepare the muscle contraction state in advance.

At startup, this preloading state allows the plantar flexor muscle group to contract rapidly and forcefully, generating strong plantar flexion force to push the body forward.

at the same time.

Pre-contraction can also increase muscle stiffness, improve muscle stability and strength transmission efficiency, and reduce the risk of joint damage during exercise.

The last step.

The dorsiflexion angle of the posterior ankle joint is set to 15°±2°.

Compared with the forefoot, the rear foot mainly assumes the role of supporting and assisting pedaling when starting.

This smaller dorsiflexion angle puts the plantar flexor muscles of the hind foot in a relatively low pre-contraction state.

But at this time, it is still possible to ensure that the necessary strength is provided when starting the pedal.

Combined with a smaller dorsiflexion angle, it helps maintain stable contact between the hind feet and the ground.

Ensure that the force can be effectively transmitted to the ground during the pedaling process.

At the same time, it avoids uneven distribution of plantar pressure and decreased ankle joint stability caused by excessive dorsiflexion.

This angle setting is also related to the body's movement coordination mode.

As long as it is properly combined with your own physiological conditions.

Can cooperate with the movements of the front and rear legs.

This can achieve efficient startup action chain.

Carter's four golden steps here.

There are indeed many things.

Indeed, it has been deeply optimized.

Following the process of constantly learning and imitating Su Shen.

Carter himself and his team unknowingly read a lot of papers and research reports published by Su Shen.

Slowly.

They also unknowingly entered the field of scientific training.

The second is...

Bolt.

This shot continues to show off his winter training results!

Here Bolt shows his differences more clearly.

What adjustments did Mills make?

Carter?

It's indeed very soon.

But.

I started this year.

Not bad either.

Come.
Chapter completed!