As a rule, runners do static stretches to prepare for running. In these stretches the runner holds a particular position for up to 30 or more seconds to stretch the muscle and connective tissue surrounding the affected joint. For example, it is not uncommon to see runners leaning into a wall to stretch the Achilles tendon and calf muscles for fairly long periods of time or bending over to touch the toes to stretch the hamstrings.
The key to successful execution of theses static stretches is to hold the position while relaxing the muscles as much as possible to get a gradual increase in the range of motion. The key element in these static stretches is muscle relaxation which is needed to counteract the muscle and tendon reflexes which tend to hold back any increases in range of motion (ROM).
These stretches have become well accepted in the U.S. and are practiced by most runners. For anyone to suggest that runners should not do such stretches is almost sacrilegious. But if we closely examine not only the research done on static stretches in regard to running but practical experiences as we will see that static stretches do not prepare you for the running or prevent injury.
Running is a very dynamic sport that requires active and often forceful movements of the legs and arms especially as you begin to run faster. Such movements which are ballistic in nature, i.e., they have a strong muscular contraction to put the limb into motion which then continues on its own momentum until stopped by contraction of the antagonist muscles. Such movements create great forces that the body must deal with.
However, when you do static stretching the amount of force being exerted is insignificant. Even more importantly, during the static stretch the muscles are completely relaxed, whereas in running the muscles perform very dynamically in both a shortening type contraction (concentric) to initiate movement of a limb and a lengthening type contraction (eccentric) to slow down and stop the movement.
The forces experienced in such movements far surpass those that are experienced in static stretching. As a result, you can never prepare yourself adequately to cope with these movements if you only prepare yourself with static stretches. This is one reason why it is not uncommon to find injuries occurring. This is substantiated by recent studies which show that execution of static stretches prior to running do not decrease the number of injuries experienced by runners. Nor do they prepare the runner for running.
The range of motion seen in running at both slow and fast speeds is determined by how strongly the muscles contract to move the limbs through this ROM. Thus an active ROM is determined by the strength of the muscles involved not by the amount of flexibility that one has. It is the muscular contraction that moves the limb through whatever range of motion is possible.
But if you have an ROM of 180° but the muscles are only strong enough to move the limb voluntarily through 150° the remaining 30° of motion will never be seen during the actual running. Because of this, to truly prepare the muscles for running the active stretches must involve the muscles through the range of motion in which they must operate.
In other words, the muscles must be activated the same as they are in the running stride. You must involve the muscles and the corresponding nerves (which send the proper signals to the muscles for a timely contraction with the intensity that is needed).
It can be said that running is a neuro-muscular activity since it requires constant firing of the nerves to activate the muscles to continue the leg and arm actions. This is a very active process. Thus to truly prepare the muscles and joints for running, especially sprinting, you must do some active activity to bring about proper preparation of the muscles and joints involved.
The main outcome of most static stretching is to permanently elongate the relevant tissues through plastic deformation. This is desirable if you have a limited ROM due to a shortened length of some component of the muscle-tendon-ligament complex. But if the ROM is not limited then the static stretching may be ill advised if the increase in ROM by static stretching compromises the integrity of the joint.
In other words the excessive stretching may stretch the ligaments or other tissues to such a degree that they no longer are elastic and return to their original shape and size. This is one of the main reasons for the increase in a number of injuries that can be seen in runners and other athletes. Because of the excessive static stretching they end up with weaker joints more susceptible to injury. The problem is compounded even more so if no strength training is done to maintain the integrity of the joint.
Most effective in such cases is to stretch and strengthen the joint through the same range of motion. When the stretches are accompanied by strengthening the danger of injury is decreased tremendously and more importantly, the muscles and joints are prepared for forthcoming activity. Active stretches which are dynamic in nature truly warm up the muscle which is an important goal of stretching in the warm-up.
As the term implies, warm-up means to increase the temperature of the muscle prior to participation. By doing active stretches with involvement of the muscles and joints through a full ROM the muscles warm-up and truly become prepared for the activity.
For more information see, Explosive Running