I ran into a physical therapist at the gym about six months ago, and after we exchanged some “hey, how ya doing” chit-chat, she revealed her frustration of the moment: “Why do I get so tight and stiff??”
I don’t think she really expected me to answer her, because she certainly knows a lot about exercise physiology, stretching, and manual therapy. But she was authentically perplexed in that moment, just as many of us are at times, about why her muscles weren’t responding readily to all the good stretching techniques she knew how to use.
Perhaps because it is such a universal, lamenting question for people over forty, this question kept surfacing in my thoughts. For months, I pondered writing about it, friends and colleagues brought up the question without my prompt, and I began to give them partial answers. I also suffered through my own minor running injuries which were attributable to tightness that wasn’t responding to stretch. Tightness can perplex even the experts!
After much rumination on the question “why tightness?” I finally decided to organize the bits and pieces of my knowledge into a more or less comprehensive explanation. (More, because I managed to come up with eight different reasons for tightness, only two of which are related to aging. Less, because I have omitted any discussion of disease-related tightness.)
While writing, I realized that I actually have a lot to say on the subject of tightness and stiffness, so in this article I will focus only on “Why does it happen?” and in my next article (mid-December) I will focus on “What can I do about it?”
If you want to cut to the chase, here are my eight reasons:
- Chronic dehydration
- Too much sitting and inactivity
- Trapped nerves and arteries
- Bursts of activity after long periods of inactivity
- Whiplash or traumatic fall
- Sudden growth spurts
• • • • •
Why do we get SO TIGHT that our muscles don’t respond very well to stretch? And, why do we start to feel SO STIFF as we get middle-aged?
Often we just give up and say, “Tightness and stiffness are due to aging.” But that’s not exactly true.
When fascia or fibrous connective tissue becomes dehydrated, the fascial layers that are supposed to glide start to stick and drag. What this means for your muscles is that neighboring muscles can become adhered together, and the separate parts within a muscle can also get stuck together. This makes a muscle group such as your quads more blocky, which makes it a little less responsive to stretch and more vulnerable to micro-tearing or strain. Drier, stickier, denser fascia provides resistance to stretch and can make you more vulnerable to stretch-related injuries. This basic understanding underlies all eight reasons for tightness that I describe below.
As women age, their fascia tends to dry out. This change can be pronounced, especially when estrogen levels begin to drop at age forty and plummet around age fifty. Men seem to get stiffer as they age too, but I don’t think this is a hormonal effect; drier fascia in older men is likely due to chronic dehydration, densification of fibers due to micro-trauma, and the other causes I describe in this article.
On the other end of the age spectrum, when men are young, their testosterone levels are naturally higher, which could actually increase their collagen production. A tendency to lay down more collagen fibers, especially in those early years of having higher testosterone levels, could contribute to tightness or inflexibility in men, especially in conjunction with other factors that contribute to tightness. (There will be more on tightness in young men at the end of this article.)
2. Chronic dehydration, especially overnight
At nighttime, our bodies are busy replenishing our tissues with nutrients, exchanging these nutrients with metabolic waste products. All this renewal and rejuvenation of the tissues depends upon ample presence of water in the tissues.
Now, if you forgot to drink enough water during the day, your body probably had to borrow some water from your muscles and skin, in order to keep your vital organs and your brain running well. When evening comes, if you quaff a few glasses of wine and have a snack before bed, your body can end up in serious water deficit during the night!
Alcohol causes you to lose water through your kidneys, and the digestion and metabolism of food uses up water, forcing your body to borrow even more water from somewhere, in order that vital organ renewal can continue. In terms of the hierarchy of importance, your body will want to borrow water from your skin and extracellular matrix, also known as your fascia, to preserve the health of your kidneys and other organs. Your muscles and fascia and skin end up suffering first from lack of water. (They suffer before the internal organs.) The glide planes within the muscles and fascia become stickier, and you wake up stiffer in the morning.
3. Too much sitting, coupled with general inactivity
A classic location for adhesion is in the middle third of the posterior thigh. We spend a lot of time sitting on our hamstrings, which presses the hamstrings against the adductors (especially if the edge of the chair presses into the muscle because the chair is too hard or too tall).
Primarily our fascia (the fibrous connective tissue that supports our muscles and joints and holds our nerves, arteries, and organs in place) is made up of fibers and a gel called “ground substance.” This gel holds a lot of water in “bound” form, which means the water in our bodies isn’t sloshing around. Most of the water that is not contained in cells is bonded to protein-sugar molecules in our connective tissue, which hold the water molecules like a sponge. Compression or continuous tension cause the “sponge” to lose water.
As the fascia loses water, the fibers within the fascia become stickier and less slippery. The protein-sugar molecules (proteoglycans) that are the basis of the gel that keeps the fibers moist are actually very much like glue; with adequate water held in the glue/gel, it is less thick and more slippery. (Imagine the difference between fresh, liquidy rubber cement and old, dried-out rubber cement. Ew! The solvent in our fascia is water (not acetone, or whatever it is in rubber cement), but doesn’t that image of dried-out rubber cement make you want a glass of water?)
So, compression, dehydration, and inactivity, all can trigger adhesion amongst the collagen fibers and between the muscle layers. A little bit of adhesion can be easily freed by stretching and/or moving the limbs in a variety of big expansive ways (followed by appropriate hydration, so that the fascial layers can suck up water and restore glide).
However ordinary walking generally doesn’t demand that these muscle groups separate very much, so, day after day of sitting, with only minimal walking breaks for exercise, will lead to the fascial layers getting even more stuck together. When you finally do experiment with a forward bend or hamstring stretch, the muscles feel short or tight and not very responsive to stretch, BUT, it is not just the muscles that are under strain.
4. Trapped nerves and arteries
Nerves and arteries run along in between muscle groups, and they can get trapped if the layers of muscle get stuck together. Branches of the sciatic nerve and the major blood vessels supplying the hamstrings pass between the hamstrings and the adductors. Big leg movements that involve multiple angles of stretch and contraction will help to keep these nerves and blood vessels gliding freely.
However, when your muscles have been relatively inactive for a long time, and you realize finally your hamstrings feel shortened and tight, the source of tightness may not be simply the muscles, it could be that the arteries and nerves supplying the hamstrings are under strain, because their capacity to glide between the layers of muscle is diminished. If you then decide to do a forward bend, which asks the the muscles to slide across one another, then the trapped nerves and arteries receive an even greater shearing strain, and localized entrapment, WHICH triggers a very interesting phenomenon (one that most manual therapists and doctors are not aware of):
Too much tension on the arteries or nerves supplying a muscle can actually make the muscle hypertonic or tight.
When you bend forward, you register the sensation of the strain as “tight muscles,” AND in fact, your muscles do reflexively tighten up in response to the physical stresses imposed on the vulnerable trapped nerves and arteries; the muscles are attempting to protect the nerves and arteries from strain and overstretch.
Athough your muscles feel shortened, it’s not the muscles’ “fault.” It’s the gluey-ness of the connective tissue, which restricts nerve and artery glide, that leads to protective muscle shortening.
Many kinds of stretches will not improve nerve and artery glide, they may even trigger increases in collagen fiber production. Inflammation around the irritated nerves and arteries will increase collagen production, and the tissues will get stiffer. The end result with nerve and artery entrapment is that the muscles will continue to feel tight or hypertonic and unresponsive to stretch. (I have remedies for this, so don’t despair.) Nerves and arteries will respond to certain kinds of stretches, and they can become more pliable and extensible again.
(Note for the anatomy nerds: Extreme local tension or overstretch-injury to a nerve can alternatively make the muscle hyPOtonic, or low-tone and semi-functional, but that’s the topic for some other article.)
5. Bursts of activity, after long periods of inactivity
Now, slightly trapped arteries and nerves usually don’t feel like a big deal when you are just sitting or walking or lying down, doing modest or sedentary activity. That’s why it is so easy for us to ignore or forget about our need for stretching and making expansive movements. But after a period of relative inactivity, when you finally decide to do yoga or some sort of stretching that you haven’t done in a long time – OR, you suddenly find yourself running around on a soccer or softball field, or climbing a steep hill, or doing some intense gardening – something else besides a protective shortening of the muscles can happen…
As I said before, if your activity asks for two muscle layers to slide across one another when they are somewhat stuck together, this transmits a shearing force to the nerves and arteries that run between the muscles. Now if you do this quickly or strongly and with many repetitions, then the shearing force is more likely to produce a message of pain or strong discomfort, because the delicate vital structures (nerves and arteries) don’t like this shearing stress at all.
Pain in this situation is supposed to be telling us, “Proceed with caution and moderation,” or, “Back off the intensity,” but it is easy to override this message and push harder, when we want to get into shape or get something done. (Especially if we are doing something we have enjoyed doing in the past, we think, “but I should be able to handle this intensity!”)
If we override this sense of pain and distress during stretching or exercising, pushing a stretch too much or holding it too long, or doing too many repetitions under a big load, then micro-tearing will occur (not just micro-tearing of muscle tissue, but also micro-tearing of the connective tissue that supports the nerves and arteries). Again, this triggers a repair response. The body will repair these micro-tears with new collagen fibers, but the newly repaired tissue is stiffer, not as well organized, and not as stretchy.
It will take time, plus gentle stretching and contraction (or specific manipulation) in order to restore suppleness to this repaired tissue. Even so, after healing, rapid and strong movements or the wrong kind of stretching can make the tissue right next to the repaired tissue vulnerable to a new cycle of micro-tearing and repair. (The repair tissue is tough, but the tissue right next to it is now even more vulnerable to overstretch, because there is less slack available in the system.) This new injury right next to the old injury increases the size of the problem area; it may “heal,” making the area even less stretchy and more vulnerable, and you soon find yourself in a chronic state of injury.
6. Whiplash or traumatic fall
Nerves and arteries running through your neck and shoulder area are very commonly overstretched when your head is thrown forward and back in a car accident, or when you take a serious tumble. Again, your body will heal these nerves and arteries, just like any tissue, by laying down supportive collagen fibers in the area, which results in a nerve or artery that doesn’t stretch as well. Then you end up with the same problem I describe above, chronic muscle tightness that is serving to protect delicate structures from further injury.
Other body parts can get whiplash too. For instance, your leg can get yanked during a serious fall, straining the femoral artery and other parts of the artery network that crosses the hip, connecting torso and leg. After the strained arteries supplying your injured leg and hip have healed, you can end up with a functionally short leg and lots of postural compensations. Your body will try to shorten up to provide some protective slack for those strained arteries, to put a little ease in the arterial network, and you will end up with lots of postural compensations for the asymmetry, and the compensations create additional sources of tightness and limitation.
Example: I can’t tell you how many times I had a “yard sale” crash, when I was downhill skiing in high school – the kind of crash where your limbs go flying and get tangled up as you hit the slope hard, and poles, skis, hat, and goggles land everywhere. This kind of fall is an instance of full body whiplash!
Even your organs can get whiplash, believe it or not. Any kind of crash (bike, car, ski) can create physical trauma in your visceral cavities. Heavy organs get thrown around, straining their ligamentous support and vascular supply, delicate organs can get bruised, and generalized bleeding and inflammation can occur. All this trauma in the torso leads to collagen fiber production and adhesion. After healing, some of the organs may stick to one another in places, instead of gliding, and this will limit torso rotation. Visceral adhesion is often implicated when someone has a stiff torso.
Widespread inflammation, rather than local inflammation, can also can lead to stiffness. Why? Inflamed nerves are less tolerant of stretch because they are already a bit irritated. With nerve irritation throughout the body, it is not very fun to move, therefore we don’t do the moderate, frequent stretching and lengthening movements that would help keep our tissues gliding rather than sticking. Widespread inflammation simply can amplify all the causes of tightness described above.
A naturopathic doctor would be an expert at tracking down the causes of widespread inflammation, if you suspect you have this. Specific foods, for example, promote general inflammation for certain people. Something else to consider: all the “eens” (including caffeine and nicotine) are nerve irritants, as are many artificial sweeteners.
8. Sudden growth spurts in young people
Even though this article is targeted toward people over thirty, there is another population of people who experience problematic tightness: young people who have recently had a growth spurt, and tall men and very tall women of any age (who all experienced major growth spurts in their youth).
The bones are the first thing to grow during a growth spurt, and all the other tissues have to catch up. During this time of rapid growth, arteries and nerves can be strained, making the muscles tight. The muscles themselves need to grow longer, and they will. Kids may outgrow this growth-spurt-related muscle tightness, OR tall guys and very tall women may develop perpetually tight hamstrings. (Tall girls are usually not as tight as tall guys, because young women’s estrogen levels are high. However, the naturally high testosterone levels in young guys may actually increase collagen production, exacerbating their hamstring tightness issues.)
My hypothesis is that when kids hit their major growth spurts, if they are very active in sports, they may be more vulnerable to the traumatic stretch or repetitive stretch injuries to nerves and arteries that I describe above. Young bodies heal well, but repair tissue is simply stiffer, even in youngsters. Unless their activity happens to naturally improve artery and nerve glide, they may end up suffering from chronically tight hamstrings and calves due to artery and nerve adhesion.
Remedies for Tightness – Check your inbox!
So now that you have a deeper understanding of what it is that creates tightness, especially what sort of events and habits contribute to inflexibility and stiffness, you are much closer to knowing just what you can do about it. In my next article, I will be sending out some specific suggestions for “what to do about it.”
This spring, I plan to make a short video (or a series of short videos) on stretching strategies for runners and hikers — “on the go” stretches for opening up sticky glide planes between the muscles, which will free up trapped nerves and arteries and make your legs feel lighter. When the videos are ready, I will post links in my newsletter.
So keep an eye on your inbox (sign up to receive my newsletter if you are not already on my list), and in the meantime drink water and keep moving!
Thanks much for reading. :~)