What is the mechanism of stretching?
Scientist have proved that majority of resistance to stretch is not from the muscle, but rather from the connective tissue framework in and around the muscle. Flexibility is achieved by applying force externally or actively to improve range of motion at joint. Muscle is composed of non-elastic collagen fibers within a protein matrix that creates various soft tissue structure including tendons, ligaments etc.To produce permanent result, Stretching techniques must be designed for more duration and to the point of mild discomfort. It takes a minimum of 6 to 10 seconds to elicit the stretch response from the neuromuscular mechanisms. Muscle tissue has two properties elastic (Temporary) and plastic (permanent).An elastic stretch is an elongation of tissue that recovers when stretch is removed. A plastic stretch is an elongation in which the elongation to tissue remains even after the stretch is removed.
What are the principles of stretching?
- Elevated tissue temperature facilitates range of motion.
- Flexibility is specific, therefore, exercise must be specific to each joint and muscles.
- For permanent effect, stretch should be held for a minimum 10 sec to 30 seconds.
- Contracting antagonist muscle will enhance stretching effect. eg- Contracting quadriceps muscle during hamstring stretch would enhance effect of hamstring stretch.
- One should stretch to the point of mild discomfort and he should avoid pull or pain feelings.
There are four types of stretches :
Static stretch– It involves a slow, gradual, controlled stretch to the point of mild discomfort and hold it for 15-30 secs. One obvious benefit in this is that the chance of injury is minimal. This type of stretching is ideal to stretch the connective tissue/non-contractile elements since it makes use of the viscoelastic properties to cause elongation of the tissue.
Dynamic (ballistic) stretch– this describes a type of stretch whereby a muscle is taken through a full, slow and large amplitude movement. The opposing muscles are used to produce the force in this type of stretching. This type of stretching is done under control and is not jerky in nature. Dynamic flexibility uses sport specific movements to increase an athlete’s readiness for competition. In contrast to static stretching, dynamic stretching is best done during your warm up as it prepares your body for the strenuous workout that lies ahead.
Ballistic stretching – is similar to dynamic stretching because it uses movement. However, the movements are quick, jerky and bouncing which triggers the stretch reflex, thereby contracting the muscle, not relaxing it. This type of stretching can be dangerous and in my opinion the risks outweigh the benefits. It involves rapid, repetitive bouncing stretch. This technique incorporates a high force, short-duration stretch.
PNF (Proprioceptive neuromuscular facilitation.) – PNF uses the concept that muscle relaxation is fundamental to elongation of muscle tissue. In theory, it is performed in a way that uses the proprioceptive abilities of the GTO and muscle spindle to relax or inhibit the muscle in order to gain a more effective stretch. It does so using autogenic inhibition and reciprocal inhibition. PNF stretching exists in a number of different forms, but the only ones discussed here will be the contract relax (CR), hold-relax (HR) and contract relax and antagonist contraction (CRAC) methods. This stretching methods involves an initial isometric contraction against maximum resistance at the end of the limbs range of motion for approximately six seconds,followed by relaxation and slow ,passive stretch at the point of limitation.
What are the benefits of stretching?
- Stretching exercise improves range of motion at joint.
- Stretching exercise at joints avoids muscular imbalances created by daily activities or exercise.
- Stretching exercise facilitates neuromuscular co-ordination.
- Stretching exercise improves blood supply and nutrient to joint structure.
- Studies have shown that nerve impulse velocity is enhanced with dynamic flexibility training.
- Stretching exercise reduces muscular tension.
