Stretching mechanism and effects

Stretching mechanism and effects

Stretching and elasticity-
Stretching is the term related with the elasticity. We can stretch those parts which have elastic property. In our body,blood vessels and muscles are highly elastic. Other smooth parts like skin,internal organs,ligaments have little elastic property. To very small extent the cartilages of respiratory system are elastic.but the bones ,especially long and flat are not elastic. (Only in the early childhood, they are little elastic.) Because of the elasticity, the internal structure protects themselves from the various types of pressures.

Stretching in living body-

In external movements like flexion, extension, adduction, abduction and rotation of various parts of the body, we have to consider the stretching mechanism of skeletal muscles. In every external movement or in any static state there is stretching of some particular skeletal muscles in varying degree. Thus in living body, during every moment somewhere is the stretch. Also in relaxed state of the body like shavasana, there is little stretch in leg muscles.
Basically, stretching is not the active work of the tissues. It is totally passive thing. In our body, we have more than 600 muscles which are attached to the bones. In the mechanism of movements, we have to consider two types or groups of muscles. i.e. agonist and antagonist. Agonist means that get contracted and helps to pull the bone for movement. This is the active work of the muscles. Antagonist means that get stretched during that particular movement. Thus the contraction and stretching are two opposite work. One is active and other is passive. In contraction we require energy but in stretching , very less or almost nothing.
When one muscle get contracted the opposite to that get stretched. Thus the degree of movement depends upon these both groups. If there is no proper contraction, then though the opposite muscles have good ability to stretch, cannot stretch properly. Or if there is no proper stretching, though the opposite muscle have good ability of contraction, can not contract properly.

Stretching is closely related with the relaxation of muscles. In fact, only relaxed muscles can undergo through proper stretch. Sometimes ,for example, due to prolonged use of weight exercise, the muscle tone get increased, so in resting state, also they remain in the state of contraction to some extent. Such person becomes bulky but not so flexible because of no proper relaxation or stretching of muscles.


Now we come to the point of flexibility. It is the movement of bone at the joint region up to its highest capability, depending upon the structure of that particular joint. In other words, it is the maximum degree of flexion, extension, adduction , abduction or rotation. Ideally flexibility depends upon following points-
Specific structure of the joint.
Health of bones, cartilages and ligaments.
Strength and elasticity of the muscles.
Calmness of the mind.

What happens during stretching-

Sometimes we observe some healthy, muscular peoples who are not able to do the particular movements to its maximum degree. This clarifies how the elasticity is important for the flexibility. In other words , greater the stretching, greater the flexibility. Let us know what happens during the stretching. But before that we must know the anatomy of the muscle. Usually the skeletal muscle is made up of two parts- Bulk and tendon. Bulk is contractile and tendon (rope like) is non contractile part. Bulk is made up of many strands of tissue called as fascicles. Each fasciculi is made up of bundles of muscle fibres.Each fibre is made up of thousands of thread like myofibrils. Each myofibril is made up of various bands called as sarcomeres. 5this is the functional unit of muscle. Each sarcomere is made up of thick and thin filaments which are arranged in overlapping manner. (one above one).These are myofilaments (actin and myosin ). Chemically these are nothing but the proteins having contractile property.
During stretching the area of overlapping of myofilaments get reduced. Thus the muscle fiber get elongated. When all sarcomers get fully stretched,the collagen fibres in surrounding connective tissue also get force so that the muscle fibre is pulled out to its full length ,sarcomer by sarcomer,and then the connective tissue takes up the remaining slack. When this occurs,it helps to realign any disorganized fibers in the direction of tension. This realignment helps to rehabilitate scarred tissue back to health. Thus the regular stretching helps to improve the efficiency of the muscles.
In some movements or posture the particular muscle is partially stretched. i.e not all fibers get lengthed. Some remains at the rest. But in some advanced asanas , some muscles get fully stretched.

Stretching and blood supply-
Mucle fibers get blood through capillary network. When the muscle fiber is stretched ,the surface area for the capillary exchange get increased. Thus more blood .rich in nutrients and oxygen get received by the muscle.Thus greater the stretching ,greater is the blood supply to them. This is also important for the health of muscular tissue.

Compliance of muscle.
When one muscle is stretched ,we can feel the sensation of the stretch. This is because of the sensory receptors (muscle spindles) located in muscle fibers and tendons. The muscle spindle contains two different types of fibers which are sensitive to the change in muscle length and the rate of change in muscle length. These send signals to the spine and then spine to cortex. Some beginners may feel the uneasiness or pain when during the stretching in asana. But after regular steady practice, the sensation of pain or uneasiness get subsided. This clearly indicates the modification in the sensitivity of nerve fibers. Thus the degree of stretching also get increased slowly slowly and one can achieve the highest degree of lengthen. This is stretch tolerance or pain tolerance. Usually it develops within 3 to 4 weeks and one can go for more degree of stretch. The greater degree of stretch may be achieved with increase in force of opposing muscles which get contracted. But that may produce the pain. After regular practice one achieves the painless complete stretch , and also it requires very minimum force of contraction of opposite muscles. This phenomenon is called as the compliance of muscle.

About viscoelasticity

Development of muscle- (long term effect )
Regular stretching plays a critical role in building muscle. Every muscle in our body is enclosed in a bag of tough connective tissue known as fascia. Fascia is important for holding the muscles in their proper place in our body. Fascia is so tough that does not allow the muscle room to expand. This may oppose the muscle tissue growth. It is like stuffing a large pillow into a small pillowcase. If we expand the size of pillowcase by stretching it,suddenly the pillow within has more room and will expand to fill that new space. By stretching the muscles we can actually stretch our fascia and give the muscles more room to grow. During stretching the muscles get pumped up full of blood. And when they get fully pumped up,they are pressing against the fascia. Thus the fascia get stretched and expanded. During the stretching of fascia, we feel a powerful pulling sensation and pressure as the muscle works against the fascia to expand it. But do not stretch up to sharp pain, let should be just a steady pull. Otherwise there is fear of muscle tear. Hold each stretch for at least 20 to 30 seconds as we must give time to our fascia to be affected by the stretch.

Rules for stretching-

Stretching should be gentle. Sudden extensive stretch may lead to stretch reflex. The muscle spindle records the change in length (and how fast ) and sends signals to the spine which convey this information. This triggers the stretch reflex which attempts to resist the change in muscle length by causing the stretched muscle to contract. The more sudden the change in muscle length,the stronger the muscle contractions which restrict the motion. If you perform gental stretch and hold it for some time,then slowly slowly you may increase the time of stretch. Thus muscle spindle habituates ( becomes accustomed to the new length ) and reduces its signaling. Thus gradually,we can train our stretch receptors to allow greater lengthining of muscles.
Muscles and ligaments are not immediately ready for the extreme range of motion. (though you have great ability to stretch ) The warm up is one of the important factor for any successful stretching. Muscles can achieve their maximum performance when all their blood vessels are dilated, enabling sufficient blood flow. At rest, muscles utilize only 15 to 20 percent of blood flow, compared to 70 percent, or more, after only 10 minutes of activity.
Stretching of unwarmed muscles is like stretching a piece of un-chewed chewing gum ,it will simply split or tear (this is what can happen in case of our muscles ). However once the gum is chewed , it becomes very pliable and we can pull it wide apart without tearing. Like this, once warm, our muscles will stretch further, giving a greater range of movement and also reduce the fear of injury. After warm up just lie down and take rest so that the heart rate will come to resting rate (72/min ) and then start stretching practice.
There should not be breath holding during stretch. It may aggravate the stretch reflex also. Continue to breath deliberately while stretching. Do breath deeply after and before the stretching.
Many times the person may suffer from chronic muscular pain without any trauma or direct injury. Acute or chronic stress is the causative factor which produces recurrent sympathetic activation. Because of this the muscles always remain in the contraction phase for a long time what we called as muscle tension. In such conditions, also it becomes difficult to stretch that particular muscle. With the help of breathing techniques, the person becomes able to reduce his muscle tension and thereby able to stretch more.

Stretching in day to day life-
Due to some occupational restraints and emotional instability, the person is not in a position to maintain proper posture thereby giving rise to various complications of muscle imbalance. Furthermore this imbalance becomes the cause of some chronic postural defects which makes one unable to use his internal organs efficiently. Regular stretching practices breaks this vicious circle. Also through breaking this vicious circle, one can avoid various types of injuries which results from muscular imbalance.
Regular stretching improves the regular body activities and the static states also. One can become able to sit in one position for a long time without producing much more strain. Although if one sit for a long time in any position ,as a part of his regular work, regular stretching helps to avoid the complications which may arise from that prolonged posture.

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