Some people confuse stretching with warm up and this is where contradictions occur. Many athletes perform stretching exercises to warm up their muscles, but, in fact, these are two different exercise groups serving different purposes.
Warm up usually precedes a workout, which distinguishes it from stretching. Warm up is a great way to prepare your body for a workout, to flex muscles and to mobilize joints and bands for a training load. Stretching is a set of exercises which are bound to improve the muscle's elasticity, joint mobility, and general flexibility.
Contrary to popular belief, flexibility doesn't mean being able to perform a split or to throw one's leg over the head. Flexibility is defined as the full range of motion of your joints or the ability of your joints to move freely, which is unique for every person and depends on many factors.
Full range of motion (ROM) is important in every sport. In martial arts, flexible joints ease your performance of a kick or an undercut, because you spend less energy and strain on it. Thus, an athlete with good flexibility doesn't get tired as fast and recovers quickly. Moreover, a person with an increased ROM is more likely to make quicker, more precise movements, and escape from attacks more easily. Stretching exercises for martial arts have their specifics to keep in mind. For those who do martial arts, doing a split isn't enough, they have to stay dynamic while doing a split. This means passive stretching should always come with dynamic flexibility and joint mobility.
A number of anatomical factors influence an athlete's flexibility, such as muscle and connective tissue elasticity. If muscles and ligaments are more elastic, associated joints will be able to perform a full range of motion.
Stretching exercises help to flex the muscles and increase their elasticity. Without stretching, muscles can become rigid, which negatively affects their flexibility. Muscles become stiff as a result of natural aging as well. The thighs and hamstring become less flexible as we age, for example. A sedentary lifestyle also plays an important role, thus, prolonged sitting causes constant tension in back muscles and chronic back pain.