# Programming the human nervous system. Stretch reflex

Published on March 10, 2017

# Programming the human nervous system. Stretch reflex

When stretching (stretching), people often do not see a stable result from mechanical stretching:

“I got sick, I didn’t work a week, I need several weeks again to return the stretching”, “I've been going to stretching for six months already, in the hall it’s already possible to sit on the longitudinal splits , but a couple of hours after the session, problems with stretching again ... "

One of the many stretching complexes, which practically does not work

What happens, why stretching the muscle leads to its shortening, how this reaction is used to improve posture - under the cut.

How does the muscle length maintenance system work?

In the muscle, there are receptors of the length of the muscle - the muscle spindles with annulospiral endings. When a muscle is stretched, a signal from them is sent to the spinal cord and a signal for muscle contraction is formed there, which returns the muscle to its original state. When I check knee reflexes at the reception, this is exactly what happens (in response to a quick blow with a hammer on the patella tendon, the spindle muscle is stretched, after which the four-headed thigh muscle is reduced - the leg jumps).

At the level of the central nervous system, this reflex (stretch reflex, myotatic reflex, muscle length maintenance reflex) closes in the gray matter of the spinal cord — the sensitive neuron (Ia fiber in the figure) switches to the motor neuron (${\alpha }_{one}$$α_1$-motoneuron in the figure).

Simultaneously with the signal to the muscle to reduce, ${\alpha }_{one}$$α_1$-motoneuron sends a signal to the Renshow intercalation cell, which inhibits the transmission of the following pulses to ${\alpha }_{one}$$α_1$-motoneuron (returning from the acceleration of the legs to the starting position will not be able to provoke the reactivation of the reflex).

The picture shows the “fast” component of the stretch-reflex, in response to rapid changes in length; there is also a “slow” component of this reflex, it occurs according to a similar system, only receptors that are slowly excited by a change in length participate in it. The "slow" component of the stretch reflex is responsible for the greater contraction of the muscle after prolonged stretching and is often included if improperly engaged in stretching.

In the picture you can see several other sources of signals for the reflex to maintain the length of the muscle.

The first is “central influences” - these are signals from the systems of preparing the muscle for movement and maintaining stability; these signals through${Υ}_{one}$$ϒ_1$-motoneuron affect the length of the muscle spindle, setting a new level of muscle length.

The second, the “pyramidal tract,” transmits our conscious signals to muscle contraction through${\alpha }_{one}$$α_1$-motoneuron; At the same time, in the pyramidal tract, about 70% of the signals are inhibitory, they prevent the manifestation of underlying reflex effects on the muscle (you can consciously suppress the stretch reflex, because of this, not all people on the admission foot jumps when struck with a hammer right away, you need to divert their attention to make the reflex work).

The hammer of the neurologist is not the most important reason for the presence of the stretch reflex.

Why do we need a stretch reflex?

The statues of a standing person require a massive foundation - the foot support area is small, the center of gravity is high, the statue cannot balance at the slightest jolts and has to weigh down the pedestal.

At the same time, a living person does not need a pedestal. Thanks to the sustainability system, he confidently maintains the balance of the body in most situations. At the lowest level of the system for maintaining body stability, a stretch reflex works.

In a static posture, the impulses of the overlying levels of the nervous system set the length of the muscles, adjusting the tone of the muscle spindle through${Υ}_{one}$$ϒ_1$-motoneuron. Deviation from a given posture causes stretching of the muscles of the body from the opposite side of the body, the stretch reflex quickly, even before the information about the deviation reached the brain, corrects the length of the stretched muscles and returns the body to its original position.

How to apply the stretch reflex to improve posture?

Readers of Giktames have already tried to improve their posture by standing for 10 seconds . In this lesson, you had to stand with your feet together, heels and socks, place your hands with the letter “T” and swing only in the ankle joints forward, without lifting your heels from the floor, stay for a few seconds in this position of the “Leaning Tower” and return to the starting position, give up.

"I tried, I did not feel anything ..."
“I tried the exercise with the slope. He leaned over, felt the tension in the muscles of the “back of the body,” starting from the buttocks to the neck and ankle (it was difficult not to tear the heels off the floor). Indeed, after the exercise, some kind of lightness felt as if it were a natural position for the body. ”
“Indeed, there is something in it: after doing the exercise, there was a feeling that excessive tension along the spine disappeared for a while.”
“The tension in the upper part of the back subsided, and today it slept noticeably better than usual, in the morning also noticed that there was less stiffness in the back, even lying down.

Chain myotatic reflex

The mechanism of the chain myotatic (stretch) reflex was involved in the lesson “Even back standing for 10 seconds”. At the time of inclination, the calf muscles first lengthen, which leads to an increase in tone in them. Then the back muscles of the hips, the muscles of the buttocks, the muscles of the loins, the longest muscles of the back, the latissimus muscles of the back, the trapezius and rhomboid muscles are included in this chain of body retention from tipping over.

When doing this lesson, you should pay attention to how the muscles are activated across the entire back surface of the body - from the heels to the crown - often people with a slouching posture do not turn their neck and shoulder girdle into motion, not deviating forward enough.

Since you are not moving abruptly, and for some time you are delayed in the “leaning head” state, receptors for the “slow” stretch-reflex component are activated, which allows the new muscle tone along the back surface of the body for several minutes or even hours to keep the body even in position standing up

Achieving evenness with this method of alignment of posture allows you to update the internal reference points of a flat posture, which acts much better than aligning yourself with external reference points (for example, standing at a wall using various fixtures or electronic posture controllers).

At the same time, it should be remembered that this calibration lesson, making this lesson more than 3-4 times a day, provokes too long muscle tension on the back surface of the body - this can lead to back pain or the soles of the feet.

PS I invite you to your seminar "Stretching without stretching . "

Beginning at 6 pm on May 26, 2017. Duration 4 hours. Moscow, Warsaw highway, 1 bld. 1, subway Tulskaya. Business center "W-PLAZA", office 603 "B", training center "Synthesis-Knowledge".

The cost of 5,000 rubles, a discount of 1,000 rubles for prepayment until May 24, two tickets for prepayment until May 24 for 7200 rubles.

Click on the link, fill in the registration form for the seminar, during the day you will receive additional materials for the meeting and details for payment.