The Physics of Plantar Fasciitis

Thursday, April 25, 2024

AMT BLOG/Performance/The Physics of Plantar Fasciitis

The Physics of Plantar Fasciitis

Plantar fasciitis, while common, can be a source of significant discomfort and limitation for your clients.

It occurs when the plantar fascia, a thick band of tissue that connects the heel to the toes, becomes inflamed due to overuse or strain.

However, what often goes unnoticed is the role that biomechanics and basic physics play in the development of this condition.

Let's consider the concept of energy distribution within the body during movement.

The body operates as an interconnected and interdependent system, with each joint and muscle playing a vital role in maintaining balance and function.

When there is a lack of mobility at key joints, such as the ankle and hip, forces generated during movement are not distributed evenly. Instead, they are redirected to areas of least resistance, often leading to overuse and strain on the plantar fascia.

If You Aren't Assessing, Then You're Just Guessing
Often times it's assumed that the cause of plantar fascia pain is due to a tight plantar fascia. From my experience, this is rarely the case.

I often see clients and athletes with very supple plantar fascia that moves quite wel,l and you can check this quickly with the Toe Lift Test demonstrated in this video.

If your client can lift their big toe actively approximately 45 degrees into extension and then passively take it to 70 degrees, then it's unlikely they have a tight plantar fascia.

So now you have to ask yourself, well, if this isn't a “tight” plantar fascia and the foot is moving well, WHY is it painful?

This is where you put on your clinical reasoning hat and look through the lens of basic physics. It teaches us that “energy moves to the area of least resistance”, and being three dimensional beings that adhere to the laws of physics, this very much applies to the body and movement.

​Step Back from the Tree to See the Forest
We are living in a body that works as a system through regional interdependence.

When pain is experienced in one area, it is often due to another part of the system not performing as it should.

So, in the case of plantar fasciitis/foot pain, looking up the kinetic chain can provide insight as to WHY the foot pain is occurring.

In this example, we are working from the Bottom-Up, starting with the Knee to Wall Test.

This is done in a half kneeling position facing a wall. Take your fist and measure from the wall to your foot, that is the minimum standard you are looking for to clear the ankle for movement restrictions.

What you are looking for from your client is:

1. Can they get their knee to the wall?

2. What do they feel when doing the test?

If they are unable to pass the test and their movement is Non-Optimal Restricted (NOR) due to a “pinchy” sensation at the front of the ankle joint, it is most likely a JOINT RESTRICTION.

If they are unsuccessful and feel a “pulling” sensation on the back of the ankle, it is most likely a SOFT TISSUE restriction.

If their ROM is OPTIMAL, but experience pinching or pulling, it is most likely a MOTOR CONTROL/ STRENGTH issue.

In any case, we go over some solutions to the above problems in this video.

Moving on up to the hip, we will use the Active Straight Leg Test (ASLR) to actively assess both hip flexion and extension mobility.

This is not just looking at hamstring length, but reciprocal hip extension as well.

Remember the flexed leg can only go so far as the ability of the opposite leg can extend.

In the context of this video we are only addressing hip extension, and limited hip flexion can also contribute to plantar fascia pain (fascial lines). But, that is covered in other videos, so go check those out as well.

Anyhoo, for this video we are going to mobilize the hip for increased extension and greater access to the gluteals for, hopefully, more efficient propulsion from the hip during gait.

The hip being the primary driver of propulsion, if the hip is unable to extend effectively, it is very difficult to drive movement from the hip, and often leading to and increased need from the ankle to dorsiflex or, greater need from the plantar flexors to push off during the gait cycle.

Full description of how to set this up is in the video. Oh and also, a progression into the lunge position for more tension and increased use of the front leg.

Continuing to work our way back down, we look at the ankle and its ability to dorsiflex.

Here, we are performing a posterior glide of the talus within the ankle mortise to create some space in the front of the joint to allow for better dorsiflexion to occur.

This typically follows the natural mechanics of the ankle when used in the closed kinetic chain (CKC) position,

However, not everyone likes to follow the rules created in textbooks, so performing some Joint Bias Testing to see what feels and works better for your client is recommended.

Which of course is covered in the AMT Level 1.

If there are soft tissue restrictions in the form of say, fascia or nerves having difficulty sliding or gliding, you can set up into a pike position, with a bit of a kickstand and perform some calf raises.

The kickstand pike position can help focus controlled tension in the posterior chain that may be causing excessive tension and pulling into the plantar aspect of the foot.

So move and load this slowly, especially if there is a neural component to the mobility issue.

Lasly, whenever you mobilize or stretch something, it's important to create control in that new range or it may not stick.

For this we use the standing fire hydrant exercise to re-connect the foot and deep hip rotators to better stack the lower extremity during single leg balance.​

And once connection is reestablished, throwing in some Airplanes or Tiny dancers to work on lower extremity control while rotating around the hip on a stable base can be both a challenging and fun exercise to perform.

I don't know if the Juilliard School of Dance will be banging down your door anytime soon, but one can dream.

In the context of this article we are only covering a VERY small number of possible contributors and potential solutions to help your clients with their plantar fascia pain.

The best thing to do is just take this at face value, and use your big brains to troubleshoot the problem and critical think about how the body is connected and works as a system.

One last note,

Protocols and quick fixes from the internet are not helpful unless you have a FUNDAMENTAL understanding of PRINCIPLES and a FRAMEWORK to work from.

If you don't have either, check out the AMT certification to provide the PRINCIPLES, FRAMEWORK and SYSTEM to build your clinical knowledge from.

Now get out there and be all you can be!



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Hi, I'm Tom Swales

Founder of the Advanced Movement Therapist Certification & AMT System

I'm a seasoned Physiotherapist and Strength Coach and on a mission to elevate orthopedic healthcare globally. I love to simplify complex practices and through the AMT system I'm empowering clinicians to deliver precise treatments and speed up patient recovery.
Let's set new standards & get patients better, faster!

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