Runners need active stretching.

Runners are advised to do static stretches before, after, and often during the run. This includes common stretches such as the standing toe touch, seated toe touch, heel to buttocks, quadriceps stretch, standing wall stretch for the calves, and elbow behind the head shoulder stretch. Many reasons are given for such stretching, which include:

1. An increase in the range of motion (ROM),

2. Reduction in the incidence of injury,

3. Delay in the onset of muscular fatigue, and

4. Prevention and alleviation of muscle soreness after exercise.

These are valid outcomes but at the same time we should remember that inappropriate stretching can be detrimental to joint integrity and stability. For example, tendons and ligaments can be permanently deformed or damaged by overzealous or prolonged stretching that decreases joint stability. In addition, overstretching of the lumbar spine can damage nerves, introvertebrial discs, and blood vessels, sometimes with serious consequences. This applies especially to passive spinal stretching in the hands of amateurs as well as forceful attempts to assume certain yoga postures which involve spinal hyperflexion, hyperextension, and rotation.

In static stretching, you hold the end range of motion for anywhere from 30 to 60 seconds. For the stretching to be "successful" you must concentrate on relaxing the muscles so that you can keep increasing the ROM. Many runners take this advice to heart and stretch as much as possible not only before running but also during the day. As a result they develop great flexibility. But does it make them better runners? No. Studies done in the former Soviet Union have shown that static stretching has no correlation to athletic performance. In my practice I have seen many runners who did an extensive amount of static stretching who were also very prone to injury. Rather than preventing injury, it appears that the overstretching creates injuries.

Active stretching, however, has a very high correlation to athletic performance. If we look more closely at static and active stretching, it will be possible to better understand why this is so. For example, static stretching normally refers to flexibility exercises that use the weight of the body or its limbs to load the soft tissues. Rarely is this term applied to stretches which are forcibly produced by voluntary muscular contractions. Active stretching, as can by typified by the "cat stretch," is employed successfully in the cat kingdom, by most humans waking in the morning, and by bodybuilders in their posing routines.

Following are some definitions that are fairly well accepted in the fitness and sports worlds.

Static Stretching. In free static stretching there is no external loading with muscle relaxation, or with isometric muscle contraction (sometimes called active static stretching). Free static stretching is usually gravity-assisted, as in the standing toe touch.

Passive Stretching. In passive stretching there is external loading on relaxed or isometrically contracted muscles. This form of stretching is usually done partner- or apparatus-assisted.

Dynamic Stretching. The most common form of this stretching type is ballistic stretching, which imposes passive momentum to increase ROM on relaxed or contracted muscles. There is an initial muscle contraction followed by passive momentum to exceed the static ROM. Also included here is active stretching, which involves continuous muscle activity to exceed the static ROM encountered during normal full range activities.

PNF Stretching Methods. Proprioreceptor neuromuscular facilitation involves intermittent or continuous phases of static or dynamic muscle action as well as relaxation or passive movement in specific patterns of activation and relaxation. In other words, the muscle is contracted and released in increments of a few seconds while moving through a particular movement pattern.

Plyometric (Impulsive) Stretching. This involves rapid termination of eccentric loading followed by a brief isometric phase and an explosive rebound relying on stored elastic energy and a powerful reflex muscle contraction. This stretch-shortening action is not intended to increase ROM but to use specific stretching phenomena to increase speed-strength of movement for a specific sporting purpose. An example of this is jumping down from a box to cause the quadriceps to undergo a quick forceful stretch and then immediately jumping back onto the box. This employs the stretch-contract reflex.

The specificity of exercise principle indicates that each one of these categories of stretching may be used effectively and safely for specific people at a particular stage of training to achieve optimal stability or mobility. Active and PNF stretching, however, which involve progressive muscle contraction and specific patterns of movement against external loading over the full range of movement, seem to offer the most effective means of improving the full range of functional performance in sport (running) and exercise. But, even though active stretches appear to be much better for athletes and runners in particular, runners persist in doing static stretches.

For example, it is not uncommon to see runners leaning into a wall to stretch the Achilles tendon and calf muscles, or bending over to touch the toes to stretch the hamstrings for fairly long periods of time. Or, to stretch the quadriceps they pull the heel of the foot to the buttocks as far as the knee will bend for 30 or more seconds. The key to successful execution of these stretches is to hold the end position for extended periods while relaxing the muscles as much as possible to get a gradual increase in the ROM. They require muscle relaxation to counteract the muscle and tendon reflexes which tend to hold back any increases in ROM.

Running is a very dynamic sport that requires active and often forceful movements of the legs and arms, especially in sprinting. The joint actions in running are ballistic in nature, i.e., they are initiated with a strong muscular contraction to accelerate the limb and to place it in motion, after which it continues on its own momentum. The movement is stopped by contraction of the antagonist muscles. Such ballistic movements create great forces that the body must deal with not only for absorption (dampening) but most importantly for accumulating energy for give-back in the push-off action.

When you do static stretching, the amount of force being exerted is insignificant. More importantly, during the static stretch the muscles are completely relaxed, whereas in running the muscles perform very dynamically in both concentric and eccentric contractions. 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 forceful movements if you do only static stretches. This is one reason why it is not uncommon to find injuries occurring.

Even PNF stretches, in which you do interval stretches to allow a joint to exhibit greater ROM, do not truly prepare the muscles. This is especially true of the stretches in which you hold a given static stretch for a few seconds and then release it before it becomes uncomfortable. After a very brief rest you stretch again, trying to increase the ROM of that joint a little more before again releasing it for a moment.

These stretches offer only a partial solution to the problem of producing natural functional flexibility. PNF stretches may do this only if they are very specific to the movements experienced in running. In addition, they must be specific to the muscular recruitment pattern and speed of limb movements. To do this requires a highly qualified specialist. 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 you have. It is the muscular contraction that creates the force needed to move the limb through the ROM.

If you have a flexibility range of 180 degrees but the muscles are only strong enough to move the limb voluntarily through 150 degrees, the remaining 30 degrees of freedom will elude you. Because of this, to truly prepare the muscles for running, the stretches must involve the muscles through the ROM in which they operate. In other words, the muscles must be activated in the same way in the stretch as they are in the running stride. You must involve the muscles and the corresponding nerves that send the signals to the muscles for a timely contraction and with the correct intensity. In static stretching, the nervous system is literally knocked out so that it can-not activate the muscles to ensure adequate stretching.

In running, the nervous system plays an extremely important role. Running is a neuromuscular activity since it requires constant firing of the nerves to activate the muscles to continually produce the leg and arm actions. This is a very active process. Thus to truly prepare the muscles and joints for running you must do some active to bring about proper preparation of the muscles and joints involved. The main purpose of stretching is to elongate the tissues either temporarily or permanently. When a stretch is done it produces either elastic extension (lengthening of the involved tissues with a later return to normal), plastic deformation (in which the lengthening becomes permanent), or tissue rupture. Exactly what happens depends upon the amount of force used and the duration of the force.

Since tissue tearing is obviously not desirable, the stretch should produce either elastic extension or plastic deformation. When there is elastic extension the stretching produces a temporary elongation, which is good when the subsequent running is of relatively short duration and takes place soon after the stretching session. But a short term increase in ROM has much more to do with nerve processes than with stretching. 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 or ligament complex. If the ROM is not limited, then the static stretching may be ill advised because the increase in ROM by static stretching may compromise the integrity of the joint. Excessive stretching may stretch the ligaments or other tissues to such a degree that they no longer are elastic. As a result they do not return to their original shape and size. This may be a reason for the increase in the number of injuries that occur in runners and other athletes since the excessive static stretching results in weaker joints that are more susceptible to injury. The problem is compounded even more if no supplementary strength training is done to maintain the integrity of the joint.

Most effective is to stretch and strengthen the joint-support structures simultaneously through the same range of motion. Full range exercises against resistance offer the greatest functional increase in ROM. When the stretches are accompanied by strengthening, the danger of injury is decreased tremendously and the muscles and joints are prepared for forthcoming activity. Stretches that are active in nature truly warm up and prepare the muscles for action, 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 are prepared for the activity.

This is why it is necessary to differentiate between the different types of stretching and flexibility exercises: to perform the most appropriate and effective static and dynamic means of increasing functional ROM. Unfortunately, the value of stretching that has permeated the literature is related to increasing joint mobility rather than achieving functional ROM in the shoulder, hip, knee, and ankle joints as they are involved in running.

Active stretches stretch the muscles and activate them in preparation for activity. When you do active stretches with resistance you can gain strength and flexibility simultaneously in the same exercise. Not only does this cut down on the amount of time needed for such training but you also get a greater benefit from the work being done. The newly created ROM is functional--which means it will be involved in your running. It is a "useable" range of motion in which the muscles are capable of moving the limb through the ROM developed.

We live in an age of specialization and sports are no exception. Running is not merely the simple act of going out and moving one leg in front of the other in a cyclical fashion. It is a learned skill that can be made more effective and efficient. Running can be improved greatly with proper training, not only in relation to how you run (technique), but also in relation to the exercises that are specific to running. This includes active stretches that duplicate what occurs in running.

by Michael Yessis, PhD

Dr. Michael Yessis is the author of Explosive Running and president of Sports Training, Inc. He is Professor Emeritus at California State University, Fullerton, and regularly works with runners to improve their biomechanical efficiency. For more information or to contact him, visit www.DrYessis.com. (Parts of this article were excerpted from Explosive Running.)