In the physiology of vertebrates, including humans, the measurement of the achievable distance between the flexed position and the extended position of a particular joint or muscle group is called its "flexibility", but this is more properly called its range of motion or range of movement. In this sense, the flexibility of a joint depends on many factors, particularly the length and looseness of the muscles and ligaments due to normal human variation, and the shape of the bones and cartilage that make up the joint.
Flexibility, or suppleness, is also a more generalized term used to compare the relative range of motion of all joints of an individual with a standard. The ability to achieve a full range of movements – to turn, stretch, twist and bend – without any stiffness, aching or suffering a spine or joint injury is defined as suppleness.
Medical conditions such as arthritis can decrease flexibility, while Ehlers-Danlos Syndrome can increase flexibility.
Those who practice dance, martial arts, yoga and contortion rely
on functional flexibility (increased range of motion with strength
and control) to perform their actions.
Benefits :-
Suppleness or flexibility is an important part of a healthful
life. Being supple means that you can reach up to take an item
down from a bookshelf, for example, or bend down to tie your shoe
laces, without feeling that your movements are restricted in any
way. When you are young, you tend to take suppleness for granted.
But as and when you start growing older, you need to spend a bit
of time enhancing and maintaining your suppleness.
Anyone can start a daily routine of simple stretches at any age to restore or increase that flexibility to your muscles as well as joints. Some studies show that you are never too old to reverse the reduced level of suppleness that comes with the age. It really doesn’t matter as to how long it has been building up.