Stretching, a very important part of a runner's life or any other kind of athlete for that matter. By regularly stretching, you avoid muscle strains, pulls or even tears. The truth is that the subject of stretching has changed a bit over the past decade or so. We now know that there is a vast difference between the kind of stretching that athletes should be performing before workouts and after workouts.
Static Stretching is defined by the American Council on Exercise as "a stretch that is performed by moving the joints to place the targeted muscle group in an end-range position and holding that position for up to 30 seconds" and should only be reserved for after the workout has been completed. Although, there seems to be no harm to the muscles to perform static stretches after a warm-up, it is recommended that the static stretching be done properly once the entire workout is completed.
Dynamic Stretching is defined by the American College of Exercise as " a stretch that mimics a movement pattern to used in the upcoming workout or sporting event. An example of an athlete preparing for an event using dynamic stretches would be a track sprinter performing long walking strides that emphasize hip extension while maintaining a posterior pelvic tilt."
Temporary deformation is a principle that refers to Tissue Elasticity which is the mechanical property that allows a tissue to return to its original shape or size when an applied force is removed and dynamic stretching is an example of this principle. While dynamic stretching does not cause a permanent improvement to tissue extensibility, these stretching techniques activate neuromuscular patterns in preparation for the activity.
On the other hand, Permanent deformation or strain is a principle that refers to the difference or deformity between the original resting length, after being stretched beyond its elastic limit. This new state of permanent elongation is also called a plastic stretch. Static stretching is an example of this principle as it improves extensibility because the tissue deformation remains even after the tension is removed.
The more you perform static stretching, the more flexible your muscles become over time and therefore limit the possibility of injury.