Flexibility refers to the ability to move joints through their whole span of movement, from a flexed to an extended position. The flexibility of a joint would rely on many factors including the length and suppleness of the muscles and ligaments and the shape of the bones and cartilage that form the joint.
Flexibility exercises is an important element of fitness and exercise tends to increase the amount of flexibility in a joint. Flexibility is also specific to the type of movement needed for a sport so it is more valuable for some sports than others. Cyclists, for example, require less hip flexibility than hurdles, and swimmers require more shoulder flexibility training than runners.
How to improve Flexibility? Flexibility can be genetic, but it can also be developed by flexibility stretches. Improving flexibility is done mainly by performing stretching exercises. All stretching techniques -Static, Ballistic and PNF Stretching are based on a neurophysiologic phenomenon involving the stretch reflex. Every muscle in the body contains mechanoreceptors that when stimulated inform the central nervous system of what is happening with that muscle.
The most usual classical stretch exercise are static stretching, sustained stretching exercises that are slow and controlled. Static stretches are regarded as safe for most persons. They include a slow, gentle stretching exercises of the muscle that is kept in a lengthened position for 10 to 60 seconds and repeated about three times, which is sufficient time for the muscle organs to begin responding to the increase in tension. The impulses from the muscle organs have the ability to override the impulses coming from the muscle spindles, allowing the muscle to reflexively relax after the initial reflex resistance to the change in length. Thus lengthening the muscle and allowing it to remain in a stretched position for an extended period of time is unlikely to produce any injury to the muscle.
Another type of stretching exercise is called Ballistic Stretching. Ballistic Stretching involves gradual increases in your range of motion and speed of movement with a controlled swing (not bounce) that attain the limits of your range of motion in a controlled manner. You never force this type of stretch. Examples of Ballistic Stretching are slow, controlled leg swings, arm swings, or torso twists.With the jerking, bouncing motion of Ballistic Stretching the muscle spindles are being repetitively stretched; therefore there is continuous resistance by the muscle to further stretch. The Ballistic Stretching is not continued long enough to allow the muscle organs to have any relaxing effect.
Ballistic Stretching exercises improve flexibility required in most sports and are often performed after a warm up before aerobic exercise training.Ballistic Stretching exercises includes 10 to 12 repetitions of the movement.Ballistic stretching uses momentum in an attempt to force a joint beyond its normal range of motion. This type of stretch should be careful because there is an enhanced risk of injury (from overstretching the muscles, tendons or ligaments) with Ballistic Stretching .
The effectiveness of the PNF techniques stretching exercises may be attributed in part to these same neurophysiologic principles. The slow - reversal - hold technique' discussed previously takes advantage of two additional neurophysiology phenomena. The maximal isometric contraction of the muscle that will be stretched during the 10 - second push phase again causes an increase in tension, which stimulates the Golgi tendon organs to effect a reflex relaxation of the antagonist even before the muscle is placed in a position of stretch. This relaxation of the antagonist muscle during contractions is referred to as autogenic inhibition.
During the relaxing phase the antagonist is relaxed and passively stretched while there is a maximal isotonic contraction of the agonist muscle pulling the extremity further into the agonist pattern. In any synergistic muscle group, a contraction of the agonist causes a reflex relaxation in the antagonist muscle, allowing it to stretch and protecting it from injury. This phenomenon is referred to as reciprocal inhibition. Thus with the PNF stretching exercises the additive effects of autogenic inhibition and reciprocal inhibition should theoretically allow the muscle to be stretched to a greater degree than is possible with the stretching exercises of static stretching or the ballistic technique.