The human foot is arguably the most complex mechanical structure in the body. This is because it has evolved to serve two almost completely opposite functions.
Over the last couple of weeks, we’ve looked at the foot as a sensory organ and its ability to absorb and manage impact forces.
Today we’re going to explore its opposite function- how to safely return those forces back to the ground in a way that creates efficient propulsion.
To achieve this, the foot must become a rigid lever.
In order to understand this, we need to understand pronation and supination.
I don’t know about you, but this is an area I was never super clear on during my university training or the first half of my career.
When you look at most joints, like a knee, shoulder or even vertebral facet joint, the function and basic mechanics are relatively clear.
Pronation and supination are far more complex, involving all 26 bones and 33 joints in each foot.
The basic understanding I left uni with (which I’m ashamed to admit, didn’t develop all that much further over the next 10 years) was:
Overpronation = flat feet = bad.
Over-supination = high arches = also bad but probably not as bad.
(I’m exaggerating a little… but not that much 😉)
When I learned a little more it became even less clear, as I discovered that not all overpronated feet are flat, and that different areas of the foot can have different patterns.
For example, it’s not uncommon for people who have high arches (a supinated rearfoot and midfoot) to also have an overpronated forefoot- essentially a torsion through the whole foot.
And when it came to what to actually do about any of it…
The truth was, I didn’t have many answers.
I’m a decent peripheral adjuster, and I know some cool muscle techniques…
But I often found these corrections didn’t hold, or didn’t clear out the compensation patterns higher up the biomechanical chain.
The good news is, these days I have much clearer answers…
And you don’t have to be a functional anatomy expert to apply them (although putting some focus on this area does help in practice… I’m always telling my associates that half of what we do is simply applied anatomy.)
The secret is understanding pronation and supination as functional patterns rather than just biomechanics.
The function of pronation is essentially to “unlock” the foot.
This is what allows us to smoothly absorb ground reaction impact forces and load them into our tissues, where we multiply them and ultimately use them for locomotion.
Without this essential mechanism, we would experience each step as a jolting shock reverberating up through our joints…
(Like bouncing around on a pogo stick with the spring removed.)
Supination has the opposite function – to lock the foot into a rigid lever so we can return those ground reaction forces back to the earth to propel us forward.
A visual analogy can be helpful here.
Imagine holding your hands outstretched with a towel loosely held between them.
This is your foot in a pronated state.
Now imagine twisting each end as far as possible to take all the slack out of the towel.
Notice how it becomes much more rigid.
This is your foot in a fully supinated state.
As we move through the phases of gait, we must smoothly alternate between these two functional states, pronating on heel strike to absorb the force and load it into our tissues, then flowing into supination during midstance and toe off to release that pent-up force to move us forward.
Whilst this locking and unlocking mechanism during gait is largely due to the bony architecture of the foot, the loading and unloading of force requires another key set of tissues- our myofascia.
This includes the muscles, tendons, ligaments and fascia.
Although the whole body is ultimately involved in this intricate dance, it is primarily the plantar fascia (with its connections to the intrinsic foot muscles), as well as the achilles tendon and the calf muscles that absorb, multiply and return the force to the ground.
The multiplication part is interesting.
At heel strike we typically impact the ground with 1.5 times our bodyweight (we covered the physics last week), but then by the time we release that force back into the ground at toe-off we generate up to 2.5 times our bodyweight in propulsive force (known as the Catapult Effect.)
This impressive engineering feat is made possible by the elastic properties of our fascia.
Think of it like an elastic band. When our foot is pronated, the elastic band is held loosely, ready to absorb force.
When our foot locks into supination, the elastic band is stretched, ready to snap back to its original length.
This literally gives us a spring in our step.
I used to see this so clearly watching my kids at little athletics. Some kids would glide round the track, barely breaking a sweat, way ahead of the pack…
While others would be a study in effort and exertion, arms and legs pumping furiously, a look of determination on their face…
Yet hardly seeming to make any progress, falling further and further behind the other kids.
This applies to your patients too (even those who are largely sedentary.)
Those who’s feet are too pronated are unable to properly absorb the force every time their foot strikes the ground.
They still receive the force…
They just don’t manage it well, so it comes out sideways, affecting tissues never designed for it, which creates injury.
In this situation the tibia is rotated internally, which directs the uncontrolled force towards the medial knee. Anyone who has pain in this area, poor patella tracking, or osteoarthritis of the knee would benefit enormously from Better Balance Orthotics.
Other common manifestations of this situation are degeneration or bursitis of the hips, as well as lumbar spine injuries.
Often these patients will tell you…
“I just bent down to pick up a piece of paper…”
This is not an excessive force injury, like someone going for a new PR on their deadlift.
It is simply a force mismanagement issue, and if you trace it back the origin is usually in the feet.
Another manifestation of this issue is fatigue…
These people are simply not moving efficiently. They are loading the ground reaction forces during pronation but unable to effectively return it to the ground by supinating their foot into a rigid lever.
They are wasting energy fighting gravity and wasting energy with every step they take. They are overloading their muscles and underutilising the natural elastic properties of their fascia.
When it comes to people with excessively supinated feet, they are too rigid- they are unable to absorb force properly.
This results in excessive wear and tear on all joints.
Think spinal degeneration, SI joint and pubic symphysis problems, lateral knee problems and once again, jolting, inefficient gait.
Not only that, the picture is often confused further by the fact that their forefoot is overpronated (as I mentioned earlier), meaning that they can display a combination of both overpronation and over-supination patterns.
In both these situations there are specific adjustments and soft tissue procedures that can help (contact me if you have specific questions or want more detail.)
However, if you want to hit the Big Red Easy Button…
(You guessed it…)
Better Balance Orthotics make a huge difference to both over pronation and over supination issues.
Just yesterday I was explaining the concept of adrenal adaptogens to one of my patients-
That if your adrenals are under-functioning, they stimulate increased function…
But if they are over working, they calm them down.
Better Balance Orthotics are like adaptogens for your patients’ feet.
This may seem counter intuitive.
When it comes to traditional orthotics, if you support the arches the wrong way (either higher or lower) you create problems.
But the key with Better Balance Orthotics is that they don’t work by supporting anything.
Instead, by stimulating the neurology and the intrinsic muscles of the feet…
They promote better function (regardless of whether your arches are high or low.)
One thing I never leaned in any anatomy class or textbook…
But saw in great detail this year watching live dissections of feet…
Is that the plantar fascia is intimately and extensively connected to the intrinsic muscles of the feet.
The bottom line…
When the intrinsic foot muscles work better, the plantar fascia works better.
Which means both pronation and supination work better.
Which means pretty much everything else in the body works better!
Keep an eye on your inbox next week for our fourth and final deep dive into the key functions of the foot that are affecting your patients and results in clinic every day.
Cheers,
