Center of Mass Management: A Missing Link in your Assessment Toolkit?

If you’re reading this, it’s probably because some part of your body hurts, and it don’t make no sense.

I get it. I had(ve) mysterious symptoms that baffled and frustrated me for years. And then I was introduced to the concept of mass management, and things finally started making sense.

No, I’m not talking about weight management…

Center of mass (CoM) management. Physics. Not physiology 😉 Not that I’m an expert in either…

Your body has it’s own personal, unique, unconscious CoM management strategy. Understanding it is a powerful tool to help your body get well.

If you have a goal of moving with more ease and less pain, I hope today’s blog post will serve as a useful introduction to what CoM management is, and why it matters. Because whether you like it or not, you’re managing your mass right now, even if you’re sitting on your butt…

Further down in this post I have a video with a simple assessment you can follow along with to start making sense of your personal CoM management strategy in your own body. Or just skip ahead to it, whatever.

Ready?

What is center of mass?

Here’s the technical definition (which is not necessarily easy to grasp unless you enjoy physics, which I do NOT, thank you Mr. Smith for ruining it for me):

“The center of mass is the point on an object at which the weighted relative position of the distributed mass sums to zero—the point about which objects rotate.“

Translation…?

Consider a sphere- Its CoM would be right smack in the middle. As the sphere rolls along the ground, the middle point (CoM) of the sphere doesn’t actually move relative to the edges of the sphere, but remains constant as the axis of rotation.

But bodies are not spheres. They are little more complex.

Imagine if someone were to tie a rope around your wrist and dangle you from the ceiling. Then (after being let down for a break), you were dangled from your ankle from the same ceiling rig. The center of mass of your body would be consistently in the same loaction no matter which limb you were dangled from.

You can also imagine it as the central axis through your body while doing a cartwheel- An axis of rotation through which no actual motion occurs relative to your limbs.

So where exactly is this central point located in our bodies?

The location of the human body’s CoM is slightly different for each individual, depending on proportions. Some say it is roughly 10cm below your navel. I’ve read it to be anywhere between L3 and S2 vertebral segments. There seems to be a lack of concensus, and probably requires exact measurement for each individual.

But ain’t nobody got time for that.

So as a general estimate, if you were to put your finger somewhere between your belly button and pubic bone, and imagine a point at the depth your spine, that ought to be good enough.

What is CoM Management?

When you walk, your body has to transfer its entire weight from one foot to the other. I tihnk its pretty increadible that we even can do it without falling down. Silly bipeds. But somewhere in our evolution standing upright and growing our brains became more useful than being on four legs, so here we are. Every step a leap of faith.

The reason we don’t fall down is becaues we have specifically sequenced and timed body mechanics that help us manage the chaotic journey we call walking. A journey in which our CoM bravely shifts from right foot to left.

In gait, the center of mass of your body needs to get all the way from one foot to rest over top of the center of mass of the other foot.

The center of mass of the foot is the 2nd (or intermediate) cunieform.

Full weight-bearing on one leg happens when the CoM of our body sits directly over top of the CoM of our foot (2nd cuneiform).

This ideally needs to happens in the loading phase of gait (or suspension phase, in AiM terms). This is when the highest amount of force will enter that limb, which makes it a critical moment in time to have our body mechanics set up in an organized way to absorb the shock.

Except a lot of the times our bodies are not so organized…

Disorganized, distorted, off-center, our CoM makes a different sort of journey.

Maybe it doesn’t quite get over 2nd cuneiform. Maybe we find a strategy that puts extra strain on different parts of our bodies to compensate for that. Maybe we spend a higher percentage of time with our weight on one foot. Or more total mass on one leg than the other.

That is the essence of CoM management: The particular way your skeleton organizes the journey of getting it’s CoM over to the opposite foot, and back again.

You could think of it as your unique “swagger”.

Why care about CoM management?

If it is true that there is a particular set of mechanics with which we’d ideally like the body to use for optimal, flowing, efficient gait (and I believe that there is), the million dollar question is: How close to that “ideal” is your body currently able to use?

This is why I think taking a presonal interest in learning about movement mechanics is a critical tool for anyone interested in actually getting well. Most of us get busy fixing things before taking the time to understand the problem.

But rather than rant about that…

Using the lens of CoM management we get different information than assessing joint range of motion, “functional” movement patterns, and strength testing alone, such as:

• Can your CoM move equally onto either foot, or is there a leg you don’t trust to weight bear into fully?
• Why don’t you weight-bear fully into one leg? Do you avoid it due to a past injury or accident?
• Which past injuries or accidents might be part of that strategy(ies) and need help now? Ankle sprain?
• What problem areas today might actually have began as solutions for a past problem?
• What body parts are you using to shift your CoM from right to left instead of actually getting your CoM to travel through space? Ribcage? Arms? Head?
• Do you stand evenly on both feet at rest? If no, how could this be putting extra pressure, compression, or tension on some parts of your body more than others?

Admittedly, this is a qualitative study, not quantitative. But that doesn’t mean it is not useful, or can’t be reasonably objective. It just requires a different way of thinking.

Like, using your whole brain.

A whole brain approach

Assessing individual body parts’ movement capabilities is synonymous with our left brain hemisphere’s limited observational style- Looking at facts in isolation and disregarding their relationship to the whole.

As Iain McGilchrist has written about in his book The Master and his Emissary, there is much evidence to suggest that we are biased to process the world around us predominantly via our brain’s left-hemisphere, which limits us to a narrow, incomplete perception of reality, dominated by hyperrationality, an affinity for the familiar, and a tendency to deny when it is wrong.

Bodies are complex systems. To appreciate their magnificence, and the impossibility that we could ever fully understand their complexity is a function only our right brain is wired for: The ability to contemplate the unknowable and find delight in paradox and contradiction.

Only via our right hemisphere can we view our bodies’ state, not as a state- one that is static, but as dynamic. How we move is not reduced to a mere utility (left brain’s view), but has an intention within a bigger context.

Our right hemisphere understands that our bodies are much more than the sum of its individual parts’ discrete abilties, in isolation from one another. Each individual body parts’ isolated performance matters, but only has meaning in context with the body as a whole.

Relationships between parts matter to the right brain, not to the left, which wants only to isolate, categorize, measure, and judge.

Our right brain can ask why THAT particular mass management strategy? How is that currently serving me? When did that begin? The left brain can only interpret individual, static moments in time, zooming in, getting the details, but missing the big picture.

Probing curiously into the unknown (asking “why”) is the realm of the right hemishphere. Fixating on what we think we aleady know (“my trainer said my iliopsoas is the problem!”) is what the left brain does best.

Understanding CoM management demands a whole brain approach.

Despite structural or functional distortions and imbalances, our bodies WILL find a way to get us from one foot to the other.

It may not be perfect, but…

…whether you like it or not, shift happens

That’s a saying we have in the AiM community. It means that your body WILL find a way to shift it’s mass from one foot to the other (if you have two feet…). How efficiently your body is able to make that leap of faith, is the question.

Has your body been forced to to distort itself in a way that protects an old site of pain, keeping it safe, but creating weird movement habits in the process?

If we aren’t considering CoM management, we are likely to be providing only a temporary solution because we truly haven’t taken the time to consider WHY the body has chosen the mechanics it is using.

Is there a leg YOU don’t trust?

Enough philosophizing… This information is only useful if you can put it into practice.

You probably trust one leg more than the other. Want to find out which one?

The short video below will help you start thinking in terms of mass management. The goal is to see if your center of mass unconsciously reacts, in the appropriate direction, to you moving your spine from right to left:

a) Moves towards front leg
b) Moves away from front leg
c) Does nothing

(This is a snippet from the Movement Deep Dive my all-access members are studying this month- A study of their frontal plane, i.e. side to side, hip/pelvis motion).

So… What did you find out about yourself? Is there a leg you don’t fully trust?

Why would you not trust a leg?

This is the question I leave you with.

Why would one lose the ability to fully commit to one leg? Or to put pressure only in one particular part of their foot?

Injuries. Accicents. Repetitive movements and postural habits. Things your mom told you. Trained movement skills, sports, etc.

What has your body been through? What needs attention now?

What if, like me, your body avoids one leg because of incomplete healing of an old (hamstring) injury? Unconsciously, I avoid committing to that leg. With each footstep, I reinforce a less efficient protective strategy to get from one foot to the other, which ends up making my neck sore.

Could this be keeping you stuck with limitations and pain that “stretching” and “strengthening” won’t help? Can you stretch out a CoM management problem?

Does your movement practice consider CoM management in your exercise selection?

These are the questions that I think are more useful than: Which exercise should I do? Or, how many reps? Or “what muscle should I blame?”

These are questions for your right hemisphere 😉

A final note: The goal of the video and the information in this post is not meant to “fix” your body. Simply provide an alternative way of thinking about why things feel the way they do. A tool to help you observe your body through the gestalt of your right hemisphere- More than the sum of it’s parts, but for the harmony with which those parts communicate.

All complaints the body makes stem from some kind of movement problem. Overuse, underuse, misuse, or disuse. And all movement problems will show up in gait. Gait won’t tell you what the problem is, but it will guide you where to look. And CoM management via gait analysis is an incredibly useful tool for making sense of it.

Oh, and if you’re not sure you can tell if there’s a leg you don’t trust, guess what… Sometimes it’s BOTH 😉

To learn more about CoM management, you may like to check out Liberated Body (a self-guided online workshop, avec moi)