How good is your bodies shock absorber?
Do you often get hip or knee pain when you run or do high impact activities?
If yes, your bodies shock absorber, the subtalar joint of the foot, may not be functioning optimally and this is something you can address!
I have never been a big runner, but in 2013 I decided to start running when I was travelling in Mozambique. This started with 10 km runs along the beach which was amazing! It was a great way to see the town I was living in.
Upon returning from my travels, I decided to continue running, in the less scenic and polluted road side pavements in the suburbs of London (before heading back to Canada).
Typically, about 15 to 20 minutes into the run, I would start getting right hip pain. At the time, I didn’t understand why.
Figure 1: The subtalar joint, and its axis, from an oblique angle
It wasn’t until I started discovering the limits of my body more (through Muscle Activation Techniques), that I realized I had, and still have to a lesser extent, VERY tight feet.
The foot has two primary functions: it needs to absorb shock and adapt to uneven terrain and it needs to become rigid so that it can transfer force and efficiently propel the body forward.
There are many joints in the foot, but one of the most important is the subtalar joint (STJ), which is the articulation between the calcaneus and talus bone (see Figure 1).
When walking the calcaneus (heel bone) is the first to strike the ground. In order to dampen the impact from ground reaction forces, the heel needs to evert or pronate (turn in), on impact and this occurs at the subtalar joint.
As the heel pronates, this leads to an unlocking of the other bones in the foot, allowing for adaption to the uneven ground.
As the body moves over the foot, the heel will eventually lift off the ground, resulting in contraction of the calf muscles leading to supination of the heel (the heel turns out).
Supination of the subtalar joint results in a locking mechanism at the adjacent joint (the mid tarsal joint) which keeps the foot bones tightly packed together so that they can’t move. Thus, the foot can transfer force efficiently.
Proper functioning of the foot is all about timing. It needs to flatten, and it needs to arch. As you may be able to appreciate, it is a complex process.
What is often not appreciated is the individual variation in bone structure that can lead to different ranges of motion.
First of all, the orientation of the axis of the STJ (an axis is a line around which motion occurs) can vary amongst individuals. This can lead to varying degrees of motion in different planes.
For example, if the axis is at 45 degrees to the transverse plane, one degree of rearfoot motion will produce one degree of tibial motion (shin bone rotation). However, if the axis is at 70-degrees, two degrees in rearfoot motion will lead to 8 degrees in tibial motion.
In addition, the subtalar joint can have between 1 and 3 articular facets (basically the contact points between the bones). A one facet configuration has lots of mobility whereas a three-facet configuration is very rigid.
Ultimately, you should be aware of the motion you have in your subtalar joint.
If your subtalar joint does not move, the foot will not absorb shock and other joints above will take extra stress (the knee and hip).
Imagine riding a bike over a pot hole with no suspension and locked out stiff arms…you will feel the shock throughout your whole body and it won’t feel great!
If you have limited range, you should strongly consider refraining from activities with high impact until you understand the issue more.
Otherwise, you are putting yourself at high risk of developing hip and knee issues later in life.
Figure 2: The subtalar joint from the plan view showing its angle to the sagittal plane (the centre line).
In order to maximise the range of motion in the joint, you need to optimise muscle function responsible for subtalar joint motion.
Figure 2 lists the muscles that both pronate and supinate the STJ. The muscles that pronate, pull from the lateral side of the axis. The muscles that supinate pull from medial side.
One of the best ways to optimise muscle function is through Muscle Activation Techniques (MAT). MAT is an approach to the assessment and correction of muscular imbalances, joint instability and limitations in range of motion within the body.
I would strongly recommend you search for an experienced MAT foot specialist if you are concerned about your shock absorber!
In the meantime, one method of improving STJ motion is through specific foot exercises.
Here are a few example videos illustrating exercises to help pronate the STJ: https://youtu.be/mOj1ZX7LK1Q
And to supinate the STJ:
I hope that all makes sense!
As always if you have any questions or comments please leave a note below or message me at john@thebodyengineers.com.