Passive movements.

Is correct to talk about stretching?

We are going to talk about all this but there is one reality that defines “stretching”, muscle contractility and elongation etc, and that is that the nervous system is the one that takes control, therefore, the resistance to elongation or to active or passive deformity is connected with the resistance of the nervous system, It is our autonomic nervous system that will reflexively or voluntarily resist to deformity (which is what is usually called “muscular stretching”).

Do you remember that in our blog we talk about  neuroplasticity?

We talked about passive movements and why they should not be called stretching.
What are the right moments to receive passive movements?
Passive movement has traditionally been used after immobilization, either by bandage, splint or formerly by plaster cast.
This has been done because after immobilization the extensibility properties are reduced, e.g. hyaluronic acid is reduced by 40% due to reduced blood supply (hyaluronic acid in the joints helps to prevent painful friction). In the cartilage it works as a restorative).
also lowers the level of chondroitin (it is a natural substance in our body and prevents other enzymes in the body from degrading the building blocks of joint cartilage), and also lowers the water and its hydration functions by 44%.

As a consequence, the stiffness and adhesions in the connective tissue are increased, and the amount and density of cross-links are known to increase.

Mobilization and stretching

To work with mobilization and stretching we have to take into account that there are 4 levels of resistance

• Intracellular level
• Intercellular level
• Fascia and aponeurosis level (endomysium, perimysium and epimysium) and also tendon level.
• Joint level

Resistance to deformation

• Joint-capsule – ligaments-tendons
• Fascia and aponeurosis – endomysium, perimysium and epimysium – endomysium, perimysium and epimysium
• Intercellular level – fibropectins and other integrins
• Intracellular level – contractile and non-contractile sarcomere components, sarcoplasmic components and collagens

Non-contractile fibers

Joint

Formed by the capsule with 47% resistance to deformation, formed by elastic fibers with collagens. Function to lubricate and allow elongation, good irrigation and good lubrication are interconnected.

Ligaments Fix bones and joints

Predominantly collagen fibers over elastins.
Binding function, therefore does not allow elongation, plastic properties

Tendons

Consists mainly of collagen fibers.
Bonds and transmits forces between muscles and bones, joints.
Binding and resistance functions

Fascia

Connective tissue that binds muscle fibers, muscles and joints. Binding, compacting, not vascularized but highly innervated.
(We have left aside the fasciae and ligaments of the visceral area).

Striated muscles

Divided into fascicles and these into muscle fibers. The fibers are polynuclear, up to 10 cm long and up to 400 microns in diameter. These may be divided into microfibrils.
Parts:

• Endomysium- Connective tissue fiber that surrounds the muscle fiber, composed of collagen and creates resistance to deformation,
• Perimysium Envelopes fascicles between 100 and 500 muscle fibers.
• Epimysium envelops the entire muscle.

All this implies a 41% resistance to deformation.

There is also connective tissue between cells and within cells (intercellular and intracellular), it is tissue that deforms and creates resistance to movement.

Intracellular resistance

Fibropectin and integrins are proteinaceous material that can double in length during neuromuscular relaxation.

Intercellular resistance,

Formed by sarcomeres. Sarcomeres are units that divide into filaments of muscle myofibrils. In these sarcomeres, resistance is generated depending on the cytoarchitectonic components of the sarcomere.
These proteins have connective tissue that generates resistance to deformation, these resistances at intercellular and intracellular level are only 1% of the total, it is not something that we can work on in a practical way, but it is interesting to know just as a curiosity.
So we are left with

The capsule has a resistance to deformation of about 47%.
Ligaments and tendons about 10%.
Fascia and aponeurosis 41%.
Cellular level 1%.

This represents in cases of muscle relaxation or immobilization studied in specific cases.

Passive mobility

Relationship with Miotendino architecture

The contractile tissue, depending on the shape of the muscle, has a greater or lesser resistance to deformation.

• Fusiforms:  The fit alignment is an example of the alveolar triceps. Greater elongation capacity.
• Peniform : Distributed by a tendon load. Example of long flexor of the fingers. Lower elongation capacity
• Bipeniform :  In the form of a plume. Distributed along the sides of a tendon. Example of the rectus femoris. Less elongation capacity than the previous ones
• Multimembranous: is more resistant to the elongation. 
• Multitendinous: This is the most rigid of all, it has its resistance to deformation. deltoid example

Muscle contraction

We can differentiate ourselves in:
antigravity muscles

Muscle boost with higher percentage of collagen fibers