Stretching is Not Stretching, And How It Really Works
When we bend forward to touch our toes, we feel what we call a “stretch” in the backs of our legs. The sensation of that stretch is familiar to us all. We may notice that after a few minutes of stretching this way we can reach further down toward our toes. The idea is that at first, our short, tight hamstrings prevent us from bending forward, and then, by pulling on them, we stretch them out. Because the muscles are stretched out, it is easier to bend forward. This is the commonly held idea about stretching.
An extension of this idea is to think that by repeatedly stretching our muscles, we can become more flexible in a more permanent sense, having physically changed the muscles. Not only does one session of stretching seem to make it easier to touch our toes, but also if we practice repeatedly, our muscles seem to stretch out more permanently, and we can more easily touch our toes on the first try. Thus, it seems that muscles are a bit like fabric: by pulling on them enough, you can stretch them out, and then they stay stretched out.
The reality is completely different than the idea. Muscles do not stretch like fabric at all. While it is obvious in our experience that the act of so-called stretching does make us more flexible, it is not the result of stretching the muscles or the related connective tissue. Most of the increased flexibility is due to relaxation of the muscles. The muscles are not getting longer because you are stretching them – they are simply relaxing. In their more relaxed state, they do not provide as much resistance to the movement, and we can bend farther forward. In some cases, a small amount of additional flexibility is gained by warming and hydrating the connective tissue that is part of the muscle. But muscle tissues and connective tissues do not get longer in an elastic or fabric-like way when you pull on them. Those tissues simply do not work that way, and never will.
Almost everyone who practices stretching exercises does so with false ideas about how the exercises are working. Those false ideas lead to ineffective use of the exercises, and often to self-harm. To understand how stretching exercises like Yoga really work to increase flexibility, one must understand how muscle tissue and connective tissue can change in length and consistency. This kind of understanding isn’t merely academic: when we know how the process works, then we can work with the process.
When we correctly understand the natural process of tissue lengthening, we can work much more safely and effectively with ourselves and others. It is possible, for example, to simply relax the hamstrings on purpose – no stretch at all – and instantly increase forward-bending range of motion. The alternative – pulling forcefully on the resisting, contracted hamstrings under the false pretense that the force will stretch them out – seems foolish when viewed from the perspective of what’s really going on.
The commonly held false ideas about stretching are so deeply ingrained in our minds that even experienced, successful Yoga practitioners and instructors may have a difficult time reorienting their perspective on this subject. However, in every case, precise awareness and understanding of the real process yields immediate and lasting benefits. For this reason, I recommend that readers choose to set aside their preconceptions about stretching, and read this article with open curiosity. The information presented here is not a theory or an opinion. It is just simple, anatomical facts about your muscles, connective tissue, and nervous system.
How Muscles Shorten and Lengthen
Contracted muscles are the primary cause of limited range of motion in the joints. When a muscle is contracted it keeps the joint that it crosses from being able to move freely. In other words, short, contracted muscles reduce flexibility. For example, the hamstrings cross the hip joint in the back. When the hamstrings are contracted, they prevent the hip joint from flexing. When we bend over to touch our toes, we are flexing our hip joints, and attempting to lengthen our contracted hamstrings. Because they are contracted, and contraction is shortening, our hamstrings do not want to lengthen.
The sensation that we call a “stretch” is the feeling generated by the nerve-endings in the muscle and connective tissue of the hamstrings when those tissues are under potentially harmful strain. The mild to moderate pain you experience while stretching is a message from your muscles to your mind. It says, “These muscles are contracted, and you are trying to lengthen them. That doesn’t make sense. You shouldn’t do that.” Pain, even mild pain, is the body’s way of saying no.
The contraction of muscles that limits range of motion during stretching is primarily caused by the muscle tone signals generated in the brain and spinal cord. Similarly, the cause of relaxation is a change in the tone signals from the brain and spinal cord. In no case does a muscle actually stretch into greater length. Instead, the act of lengthening a contracted muscle against its own resistance causes the stretch receptors in the connective tissue to send a “danger” signal to the spinal cord. If the stretch is strong enough, then the spinal cord responds by causing the affected muscles to contract more. In other words, when you stretch a contracted muscle to the point of pain – even just moderate pain – the body responds by making it more difficult for you to lengthen that muscle. This makes sense, since the body is attempting to keep you from tearing the tissue. Despite this fact, most people who stretch do so in direct opposition to their body’s natural protective mechanisms. The sensation that most people associate with stretching is in fact the sensation that makes lengthening muscles more difficult.
The reality is that contracted muscles only relax when the tone signal from the brain changes, and that is most likely to happen when the muscle is not under strain. In other words, the desired effects of stretching are most easily and efficiently achieved while we are not stretching. To inspire the brain and spinal cord to soften the tone signal to a muscle, it works best to deactivate the stretch receptors by shortening the contracted muscle – the opposite of stretching. This in turn deactivates the protective tone response that comes from the spinal cord, and tells the brain that the muscle is already softening. Once the brain and spinal cord are aware of and participating in the softening of the muscle, then it becomes possible to draw the muscle slowly into length, without activating the stretch receptors or the protective tone response. Shorten the muscle first, and then when it begins to soften, lengthen it slowly and gently.
To really understand this process, you must experience it yourself. This is best accomplished under the guidance of a qualified instructor. However, in the interest of making this article as useful to readers as possible, I will describe two exercises that demonstrates the muscle relaxation process in the context of effective stretching. I learned the first exercise from one of my yoga teachers, Richard Freeman. The second exercise is my own modification of the technique for more flexible people. Try both.
Stretching Exercise for Relatively Inflexible People
- Lay on your back with your legs resting against the wall, knees bent, the bottoms of your relaxed feet pointing toward the ceiling. Scoot your butt as close to the wall as you can. Relax your neck, shoulders, and stomach. With your knees bent and your feet relaxed, you should not feel a stretch in your hamstrings. If you do feel a stretch, bend your knees even more.
- Flex your ankles, spread your toes, pull them back toward the floor, and push your heels toward the ceiling until the bottoms of your feet are parallel to the ceiling, and begin to slowly straighten your knees. This should produce a feeling of stretch in your hamstrings. If it doesn’t, and you can easily straighten your legs, then this exercise will not work for you. It is too easy. But for many people, the feeling of stretch will be strong enough that it may be impossible to fully straighten out your knees. Experiment with your pain tolerance. Give yourself the sensation of ineffective stretching by lengthening your contracted hamstrings against their own resistance.
- Rest by allowing your knees to bend and your feet to relax. Reach up and massage and karate chop your hamstrings, quadriceps and glutes in an enjoyable way. While you are massaging yourself, gently point your toes, and relax them, point and relax. Just wiggling your feet a little bit. You can also gently bend and extend your knees – not to the point of stretch, but rather to enjoy un-resisted movement. This is shortening and softening the muscles before lengthening them.
- Now begin to slowly straighten your knees, while still massaging your legs and gently wiggling your feet. Use the massage and movement to continue to encourage your hamstrings to relax. Don’t push into the painful part of the stretch, just massage and move your way into the gentle extension, emphasizing the softness of your hamstrings rather than the sensation of the stretch.
- If you have successfully relaxed your hamstrings, then your knees should begin to straighten softly without producing very much stretch sensation. With a little bit of practice, it should become fairly easy to straighten your legs and flex your feet without much resistance at all. When that happens, rest with your legs straight, and reflect on what stretching isn’t, while you happily wiggle your feet.
- When done properly, this exercise demonstrates that muscles lengthen more easily when not under strain, and that relaxation by shortening first, then lengthening, is more effective than sustained, semi-painful stretching against resistance. Since most people have habitually stretched against resistance for their entire lives, it can be quite a challenge to conjure up the patience and curiosity needed to explore this more gentle, conscious way of relaxing into length. However, once you directly experience the process, and understand the natural mechanisms at work, it becomes apparent, and even obvious, that fighting against oneself in a sustained, semi-painful stretch just doesn’t make sense. Once you are able to engage in the process, then it becomes clear that if you have the ambition to increase your flexibility, the best thing you can do is leave your ambition at the door. Real lengthening happens more quickly when approached slowly and gently.
Stretching Exercise for More Flexible People
Less flexible people can do the first five steps of this exercise, and experiment gently with the rest as long as it remains comfortable. Remember, these stretching exercises barely involve any stretching. If you are pushing into mild discomfort and you need to breath deeply to overcome the intensity of the sensation, then you are not following these directions. For some people, it takes quite a committed effort not to push.
- Sit on the floor with your feet in a relaxed c-shape in front of you, like a baby playing with toys in her lap. Allow your knees to be bent enough that you feel no stretch in your hamstrings or thighs. Wiggle your feet, wiggle your legs, and move your pelvis to encourage them to relax. Flex and extend your spine gently to encourage it to relax. Breathe, sigh, and soften yourself all over.
- Now move one leg so that it is turned out to the side, bent at the knee, and relaxed. Now both knees are bent in the same direction and your weight is more on one hip than the other. Again, wiggle your feet, flex and extend your spine, and gently twist at your waist and hips to loosen everything up.
- Bend forward over your forward knee and place your forearms on the floor to either side of the knee. This should not produce a stretch in your hips, thighs, hamstrings, or low back. If it does, then come up onto your hands and continue the exercise from there. Also, to reduce the stress, bring your forward foot in toward your midline, increasing the bend in your knee.
- From the forward-bent position, again flex, extend, twist and rotate your spine and hips. Walk your forearms over to one side of the knee, then to the other. Remember, if there is any stretch at all during this exercise, it is very, very mild. Anything more, and you need to back off. You are not stretching yourself, you are relaxing yourself.
- Come up off your elbows and place your hands on the floor. Extend your back leg out behind you and square your hips over your front leg. This will bring your butt up off of the floor, and may create a stretch in your hip, thigh, and hamstrings. If it does create a stretch, come up higher on to your hands, supporting yourself more with your arms. As the exercise progresses, you will have the opportunity to lower down again as your muscles relax. Again, move your body in a relaxing way. In this position, it feels nice to wiggle your whole body a little bit. Try moving your back leg in a relaxing way.
- Walk your hands out, one step at a time, to slowly begin to explore a very gentle stretch in your hip and hamstrings. Walk your hands out, and move and relax your whole body as you lower yourself down. Eventually, you will be able to lower yourself slowly back down on to your forearms, one on either side of your forward knee.
- Once you are resting comfortably on your forearms, with very little stretch in your hip and hamstrings, rest, breathe and relax. Rock your whole body from side to side, leading with your hips. At this point, you are working directly on relaxing the muscles of the outside of your hip, your inner thigh, your low back, and the backs of your legs. Move in relaxing, enjoyable ways.
- Begin gradually lowering yourself down, moving and relaxing, until you can rest your chest on your forward knee, forehead on the floor, arms relaxed. From here, move your body in relaxing ways. Come up out of the forward bend, and melt back into it. Melt your legs, hips, and low back. If you find yourself going into a strong stretch, back off, breathe, soften your attitude, drop your hurry, and focus on the feeling of relaxation rather than the feeling of the stretch.
- Come back up onto your hands and extend your forward knee a little bit, so that it is farther from your midline. Flexible people may approach a right angle at the knee. Flex and relax your ankle, and move your hips and spine. Repeat steps 6 through 8 with your knee in this more extended position, until you can rest your chest on your knee. Very flexible people may be able to rest their forehead on the instep of the forward foot. All the while, instead of stretching, you are relaxing into the movement and softness of the position.
- Change legs and repeat from the beginning.
How Connective Tissue Shortens and Lengthens
So far, I have described how muscle tissue shortens and lengthens. But muscles are comprised of two tissues: muscle tissue and connective tissue. Muscles are infused throughout with a web of connective tissue. The tendons at the ends of muscles are comprised entirely of connective tissue. Ligaments and joint capsules are also comprised entirely of connective tissue. While some connective tissue in the body can stretch a little bit, the stuff within muscles, tendons, ligaments and joint capsules cannot stretch at all. It is made of a protein fiber called collagen, and collagen does not have any elastic properties. When you pull on collagen fibers, they do not stretch. If you pull hard enough, they break.
Pulling on collagen fibers by stretching the into length is even less effective than pulling on muscles, since unlike muscles, collagen fibers don’t have the option of relaxing. Since they don’t stretch, and they don’t relax, collagen fibers just resist until they break. Tendons and ligaments are really tough, but the fiber network that weaves through every muscle of the body isn’t as strong. Painful stretching can tear those collagen fibers and lead to inflammation. If you’ve ever stretched so much that you were sore the next day, you tore collagen fibers. Even though they are strong, people frequently damage their tendons and ligaments with repetitive, painful stretching exercises.
Collagen fibers may be tough and inelastic, but they also have the remarkable property that allows them change consistency when massaged. The property is called thixotropy. Thixotropic compounds are firm when standing still, and become more liquid when shaken or moved. Synovial fluid in joints and the ground substance between cells are both thixotropic. Because all of the collagen fibers of the body are bathed in and infused with synovial fluid and ground substance, tendons, ligaments and joint capsules have thixotropic qualities. This means that when you massage them, they get softer. Tendons, ligaments and joint capsules don’t stretch when you pull on them, but if you gently agitate the fluid that surrounds and infuses them, the bonds between the fibers weaken, and places where the fibers are bound and scrunched up unbind and un-scrunch.
The thixotropic quality of synovial fluid and ground substance decreases when inflammatory mediators are activated. This means that if you tear collagen fibers, then the inflammatory mediators are activated, and the surrounding fluid gets thick. Likewise, the collagen fibers themselves become sticky. Stretching to the point of pain causes micro-tearing of collagen fibers, releases inflammatory mediators, and makes everything get thick and sticky. In contrast, if the inflammatory mediators in the ground substance and synovial fluid are not activated, then the fluid can become much more viscous and the collagen fibers much more slippery. The only time collagen fibers can change length at all is when they are in this soft state. Painful stretching makes this state impossible.
In the right chemical environment, collagen fibers can become surprisingly viscous – something like unbreakable snot. This extreme thixotropic state is rare, since inflammatory mediators are active so much of the time in people’s stressed out tissues. The attitude of always pushing forward, hurrying, and pushing into painful stretches rules out the possibility of super-viscosity of connective tissue. But when we slow down, gently massage the tissue, and breath easily, it can transform entirely.
There is no other way to cause this remarkable state-shift other than to stop pushing and start relaxing. Thus, combining muscle relaxation with restful breathing and gentle massage is the most effective stretching method – and it involves no stretching whatsoever.
General Principles for Effective Stretching
Think of stretching as soft releasing. Don’t push into anything, ever. Shorten and move until you relax, then slowly and gently lengthen, allowing your muscles to soften before you feel anything more than a very gentle stretch. Move into and out of each stretch again and again, changing it into a slow, repetitive movement rather than a long hard push. Rest often in neutral positions. If you ever do anything that causes you to have strained breathing, you are pushing way too hard. Stop, shorten, soften, breathe easily, then slowly lengthen into the easy, natural space.
If you practice Yoga and you apply this lesson in your practice, then your Yoga experience will be radically affected. You will no longer be able to go as deeply into any of the poses. You will look even more like a stiff person. You won’t impress anyone. On top of that, you will progress very slowly and mindfully through everything, falling way behind in yoga class. You will move into and out of the poses again and again, shortening, softening, lengthening, resting. It won’t look like yoga anymore. It will look like moving and relaxing. You won’t experience very much intensity. It will be easy to breathe.
Why Stretching Ineffectively Still Works (Sort Of)
When you lengthen a contracted muscle to the point of pain, your breathing intensifies, and you continue to push, you can overpower your body’s own protective response. This is kind of like winning a fight with your spouse by yelling so loud that they acquiesce to end the conflict, or like winning an arm wrestling match when your opponent finally gives up. Your opponent in this case is your own body, and the loser of the argument is also your own body. It is quite possible to train your body in this way, so that gradually, it gives up its tension and submits willingly to your forced posturing. Even if it seems effective and doesn’t tear your muscles and tendons in the process, it is still never actually stretching. In many cases, forceful stretching is the cause of muscle strain, joint sprain and joint instability. Practicing stretching harmfully while a person is young may seem fine, but often people suffer the consequences later in life. Ineffective stretching during yoga is the cause of an unfortunate amount of low-back, hip and shoulder pain.
Even if it doesn’t hurt you, painful stretching is a slow way to increase flexibility. Do an experiment: Try a painful stretch and notice how much progress you make. Then, re-do the exercise, working much more slowly, with relaxation, movement, and almost no stretching. If you have understood this lesson, you will naturally move much more deeply, much less painfully into every non-stretch position. Your Yoga teacher will notice the difference too!