This is the temporary lengthening of soft tissue due primarily to the elastic properties of all muscles.
Elastic elongation is accomplished by stretching exercises.
It temporarily increases the extensibility of the muscles. This is the permanent lengthening of soft tissue. This is seen more in ligaments than any other soft tissues. Once a ligament is stretched, as in the case of a joint injury, it will never be as taunt as it once was. Chronic flexibility exercising can also stimulate plastic elongation, which is not necessarily a bad thing.