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Archive for the ‘Flexibility’ Category

I Wanna Be FLEXIBLE!!! (Part 2) —

So I left off a while back having discussed the MAIN STRUCTURAL COMPONENTS responsible for flexibility (bones, ligaments, etc.) to give some idea of the hard limits that we have to our total joint range.  But as most of us realize, that’s not the whole picture.  After all, it’s not usually our skeleton that’s restricting us in day-to-day activities.

Where do we typically feel “tight” instead?  In our muscles!  And that brings me to the major focus of this blog entry — the NEUROMUSCULAR SYSTEM!!!

You see, the primary job (mechanically speaking) that our muscles have is, simply put, managing joints.  Put another way, they’re primarily responsible for making sure that the bones can actually maintain proper contact with each other, can move (or not move) properly, and that force can be distributed throughout our bodies in an appropriate way.  If our muscles are working well, then we’re having a good time.  If not, then we start to see dysfunction — in the form of pain, arthritis, weakness, poor performance, coordination issues, and all sorts of other not-so-fun stuff.


A less-than-optimal neuromuscular system often leads to pain and other issues -- from

A less-than-optimal neuromuscular system often leads to pain and other issues — from


So to illustrate how some of this works, we have to break down the actual structure of a muscle and the “stuff” it interacts with.  Note that this will be PRETTY basic, but there’s still some science ahead.  So saddle up!

Muscles are, at least in my opinion, some of the coolest things ever devised by nature.  They consist of tons of tightly packed subcellular machinery that allows our bodies to convert the chemical energy of our food and the products of food breakdown into actual mechanical energy (FORCE)!  This is no small feat.  I won’t get into the metabolic pathways and mechanisms that govern this right now, but just know that there’s a lot of stuff that has to happen for your muscles to work!  So let’s talk a little about their structure (feel free to skip this portion if you’re already familiar with basic muscle structure):




***Keep in mind that this post is going to talk about skeletal muscle.  This is the stuff that attaches to our bones and helps us move.  There are two other types of muscle — cardiac (heart muscle) and smooth (which operates in our organs and around blood vessels) — but this isn’t immediately relevant to us.  So I’ll stick to skeletal muscle today.***


First off, I want you to look at the structure of a typical muscle.  Notice that it’s a big hunk of tissue that’s attached to a bone by something called a TENDON.  But when we break it down, we see that the whole muscle is actually comprised of a bunch of chunks of  muscle units called “fascicles.”  The word “fasciculus” actually means “bundle” in Latin.  This makes perfect sense, as you can see that each fascicle is really a bundle of individual muscle fibers.  I sometimes like to think of it as a bundle of straws wrapped in a thin sheet of tissue.  And all of those bundles come together to make the whole muscle.  Also– in muscles, a “fiber” is the same thing as a “cell.”  So keep that in mind if you see it anywhere else.  Again, FIBER = CELL.



Muscles have a really cool structure — notice how muscle fibers (cells) are bundled together into fascicles, and then THOSE are bundled together again. It all packs together into what we know as a whole muscle — Taken from


This gives a good basic overview of how our muscles are organized on a larger scale.  Now let’s look a little closer at a single muscle cell (one of the straws) to see how it’s put together:


So we see that, even on a smaller scale, things are bundled up in a similar fashion.  Inside a single cell, we see these individual cylinders called "myofibrils" that have their own components within THEM -- from

Smaller bundles of “straws” within each of the ones from the previous diagram — from


So we see that, even on a smaller scale, things are bundled up in a similar fashion. Inside a single cell, we see these individual cylinders called “myofibrils” that have their own components within THEM.  It is within these myofibrils that the smallest functional unit of a muscle is found — THE SARCOMERE.  I won’t get too deep into how this little guy works, but suffice it to say, these are where the magic really happens.  Here’s one last picture to help you visualize things on this microscopic level:


A diagram of the basic structure of a SARCOMERE -- from

A diagram of the basic structure of a SARCOMERE — from


So all you really need to know about sarcomeres is this — tiny little proteins (filaments or myofilaments) inside the sarcomere attach and “crawl” over each other so that each end (the Z-disc or Z-line) is pulled toward the middle.  Now all of these sarcomeres are attached end-to-end (in “series” as it is known).  If we zoom back out a bit, we can imagine how the whole muscle will shorten as each individual subunit shortens.  Here’s a neat way to visualize this:

Imagine you and nine friends are all side-by-side, and you each represent a single sarcomere.  You each have your arms outstretched and are holding hands with the person next to you.  Now imagine that, while doing this, you’re sitting on a REALLY slick surface so you can pull all of the people on either side of you closer to your position.  If you pull your arms in (“contract” like a sarcomere), you get “thinner” and the people on either side of you will slide in towards you.  The overall length of the system (all 10 people) will get a LITTLE BIT shorter.  Now imagine if ALL TEN of you do the same thing.  Every person pulls the people they’re holding hands with closer to them.  As you might imagine, the whole chain will get MUCH shorter, as everyone is pulling their arms in at the same time.  This is what happens within a myofibril, and within a whole muscle on a larger scale.  The whole muscle shortens, because TONS OF INDIVIDUAL SARCOMERES SHORTEN.

I mentioned earlier that muscles generally attach to our bones at what is called a tendon.  While they don’t generate force directly, healthy tendons are absolutely vital for allowing us to transmit that force from our muscles to the bones (or vice-versa) and do all of the things that we ask our bodies to do.  If a tendon fails, then the muscle can’t do its job.  This is important to keep in mind, as these structures are often overlooked when we talk about building strength and power and developing our physiques.  We’ll look at tendons and how they are involved in stretching a little more later.




So from all of this, we can see that there’s an intricate structure that contributes to the way our muscles do their jobs.  Millions of tiny units work together to create the large-scale movements that we see and use every day.

I needed to go into the structure of muscles a bit so you have a basic understanding of the pieces that make up the whole.  Muscles are an intricate (and WAY COOL) system of components that come together beautifully to allow us to perform all of the actions of daily living that we take for granted.  Without muscles, there is no controlled movement.  So now that you know a little bit more about how muscles are put together, what about the effects of stretching?  How does attempting to move into extreme ranges affect these tissues?  I’ll describe this in the next entry 🙂


I Wanna Be FLEXIBLE!!! (Part 1)

Well friends, it’s time for another update.  Based on some recent observations (and a good bit of input from some friends and family), I feel it’s appropriate to discuss a topic that seems to be on everyone’s mind — FLEXIBILITY!  (Warning, this’ll be a little longer than my last entry)

It seems you can’t go half a day without hearing someone in your social network or at the workplace talking about how “tight” something feels.  If you were to ask a random room of 200 people from all over this country which ones feel they need to be more flexible, almost every hand would shoot up.  It’s seen as a universally good thing to be flexible.  This is common knowledge.  Right?

Hmm… not so fast.  First off, what IS flexibility anyway, and how can we affect it?  Some people would define flexibility as the ability to move throughout a certain Range of Motion (ROM) at various joints.  Others describe it more as a sensation of “looseness” or softness in the muscles that often like to tighten up.  At the end of the day, we have probably all known those people who seem to be able to contort themselves into all sorts of wacky positions without trouble.  We also know other people who are at the other end of that spectrum (and maybe you’re one of them!).

Isn't it just so unfair?  We all know those people who can do ridiculous things with their body.

Isn’t it just so unfair? We all know those people who can do ridiculous things with their bodies. — (Wikipedia image)

So I’d say it’s all kinds of things, depending on the person and the goals.  A person’s overall capabilities in terms of flexibility/motion will depend on two main factors: 1) Structural limitations and 2) Neuromuscular capabilities.  Sadly, there’s no way I can cover all of the intricacies of the topic in a single blog post.  For this post, I’ll describe a little bit about joint structure: 



This might sound silly, but first we have to define a joint.  A joint is any place where two bones come together/interact.  Note that I didn’t say they have to MOVE!  This is important.  Some joints are completely fused, while others have a little or a lot of motion allowed.  A super detailed description of all of the variations is beyond the scope of this post, but be aware that there are differences.  I’ll probably go into more detail in a future segment that I post as a permanent link.

There are a few fancy words that anatomists and biomechanists use to describe the structure and function of the joints in question.  Specifically, a synovial joint is surrounded by a joint capsule that contains synovial fluid for lubrication and nutrient flow.  The term diarthrodial is often used interchangeably with “synovial” and describes a joint that is “freely moving.”  These are the joints that we most often think about as contributing to the movements that we try to accomplish throughout the day.  Synarthrodial joints, on the other hand, are fused and allow essentially no motion (such as the sutures fusing the separate bones of your skull).  Amphiarthrodial joints allow some movement (think of the intervertebral joints in your spine, etc.).


A breakdown of the six basic categories of synovial joints

For the purposes of this discussion, I’ll focus on synovial /diarthrodial joints.  There are six (6) generally accepted subtypes within this joint category that most of us in the exercise industry are used to.  Note that I have taken the images in this section from the “Synovial Joints” section at  It’s still a little simplified, but it can give you a decent idea of the structure and function beyond what I’m writing about here, and I think the diagrams get the point across nicely.

Anyway, let’s take a look at a “typical synovial joint” as well as the passive structures in the knee joint to get a sense of what’s going on here…

A generic synovial joint (note an enclosed capsule and articular cartilage on the surfaces between bones)

A generic synovial joint (note an enclosed capsule and articular cartilage on the surfaces between bones)

A more realistic diagram of an actual synovial joint -- the knee

A diagram of an actual synovial joint — the knee

So you’ll see that there are a number of structures in a joint that we need to be aware of.  Any one of these can have profound impacts on the ability (or inability) for that joint to move properly.  Let’s take each of these pieces one at a time:

1) The articular cartilage is an extremely smooth covering on the ends of the bones.  It pads and protects the bones from wear.  It also allows for the joints to move smoothly by allowing the ends of bones (articular surfaces) to glide almost effortlessly over one another.  This stuff is REALLY slick!  Note that irritation of this tissue from abnormal stresses can result in problems like osteoarthritis and cause inflammation that limits your range of motion.  That said, proper motion is actually HEALTHY for the joint tissues (including the cartilage).  Cartilage can adapt to stresses and become thicker/stronger where it is loaded IF you do so properly.

2) The tendons are fibrous bands of tissue that connect muscles to bones, allowing them to put force through the bones.  As will be discussed in a later entry, all movement ultimately depends on our muscles’ ability to deliver force to our bones in a sufficient and reliable fashion.  As is the case with muscles, bones, and other joint structures, tendons can adapt to stresses to become stronger.  More on this later.

3) The synovial cavity is the cavity within the joint that contains the lubricating synovial fluid.  This fluid reduces friction in the joint and allows for a sort of nutrient circulation throughout the joint.  The joint tissues can actually begin to atrophy and die without proper flow of these fluids.  Think of the fibrous tissue of the synovial cavity as kind of spongy.  In order for the tissues within the joint to receive proper nutrients and flush out toxic byproducts and waste, we have to “squeeze out” the sponge and then release it again.  We do this through loading and unloading the joint periodically through normal movement.

4) The ligaments are completely passive structures that attach bones to each other and keep the joints moving along a relatively predetermined path.  Too much stiffness in these guys (from scarring/fibrosis, adhesions, etc.) can cause limitations in motion.  Conversely, too much looseness/laxity in ligaments can result in joint instability and a predisposition for abnormal wear and/or dislocations.  When we do a significant amount of stretching, we can (potentially) affect the length of these tissues.  When we stretch out a ligament, it doesn’t readily return to its old length.  That’s something we have to keep in mind when we do really intense stretches, as I’ll discuss later.

5) The bursae (plural of bursa) are small fluid sacs that reduce friction by keeping bones from rubbing against each other and/or prevent soft tissues (tendons, etc.) from dragging over bones and wearing out.  Soft tissue specialists sometimes focus on massaging and manipulating these tissues to allow for greater mobility in a joint.  In extreme cases where they are doing more harm than good, they may be surgically removed.  I’m not currently an expert on the function of these structures, so I’ll save discussion on them for another time.

6) Finally, note the bones themselves!  People often forget about what is the most important passive structure for determining motion.  How are the bones actually shaped???  I’ve seen blatant ignorance of this in a number of places over the years.  But let me say it here and now — YOU CANNOT VIOLATE YOUR STRUCTURE WITHOUT CONSEQUENCES!!!  Some of the worst offenders are martial arts schools and ballet/dance academies where a great deal of emphasis is put on range of motion without a proper understanding of how to manipulate it.  Whatever shapes your bones and joints have will directly dictate what movements you’re capable of accomplishing.  If your pelvis and femur look nothing like Sally’s, you’re not going to be able to do the same movements that she can do.  Period.  You can check out this picture for an illustration of my point:


Note the different shapes we see in people’s femurs. It isn’t hard to imagine that different shapes allow for different degrees of mobility. I’ll explore the hip in more detail in a future post — (Image from Wikipedia)

Now that doesn’t mean it’s all bad if your structure doesn’t allow for a great deal of movement.  Sure, it’s a cool party trick to be able to drop into a split at a moment’s notice, but you make up for that with something that might be much more useful: STABILITY!

You see, your body liberates movement at the expense of stability.  If you let something move around a lot more, then you can’t anchor it in place as well and keep the bones as secure.  Think of the shoulder and how mobile it is.  Now think about how often that thing gets dislocated compared to other joints!

Likewise, if a joint is held in place with more passive structures (bony articulations, ligaments, tighter joint capsule, etc.), then there won’t be as much opportunity for movement.  Dislocations at the hip don’t happen nearly as often as at the shoulder, but you also can’t move it as freely.  In most cases, at least.

What was all that?!?

What was all that?!?

So I apologize if that was a wall of text, but I needed to cover that basic information in order to move forward.  There are a variety of structural variables we have to consider before looking at how we can really move.  Our structure DETERMINES our function.  Once we’ve discovered what our opportunities for movement are, we can then look at our ability to CONTROL that movement.  For that, we’ll have to look at the neuromuscular system and develop more of an understanding of how we tend to become “flexible.”   That’s coming up in PART 2

Thanks for reading!