Flat Feet & Plantar Fasciitis: Why Arch Strength Matters More Than Arch Shape

Dr. Angela Walk
Jun 25
5 min read

If you’ve been told that flat feet or high arches are the reason you have plantar fasciitis, you’re not alone. It’s one of the most common misconceptions I hear in practice.

But here's the truth: It’s not the height of your arch, but rather the strength and function of your arch that determines your risk for plantar fasciitis.

In this post, I’ll explain:

Why weak arches—not flat or high ones—cause problems
How conventional shoes contribute to arch dysfunction
And the most effective ways to rebuild your foot’s strength naturally

What Really Causes Flat Feet?

Flat feet occur when the arch muscles of the feet are weak and unable to maintain their natural shape under load. It’s not a bone problem—it’s a strength and usage issue.

Yes, genetics play a role. Some people are born with naturally lower arches. But the cause of functionally flat feet in most people isn’t genetics—it’s footwear.

Why?

Conventional shoes:

Pinch the toes together—especially the big toe
Elevate the heel, shifting weight forward and disengaging the arch
Restrict movement, preventing muscles from activating properly

Over time, this creates dysfunction. The big toe (hallux) becomes weak and pulled inward. The foot loses its natural ability to spread, splay, and stabilize, and the arch collapses—not because of your structure, but because of inactivity.

The Flat Feet = Plantar Fasciitis Myth

Having flat feet or high arches does not automatically cause plantar fasciitis.

What does? A weak, dysfunctional arch that can’t tolerate the repetitive loading of walking, standing, or running.

Many people with high arches have plantar fasciitis. Many with flat feet do not.

The determining factor is how well your feet function under load—not what they look like on a footprint test.

Focus on Function, Not Appearance

The appearance of your feet doesn’t predict pain. What matters is:

Arch strength

Foot mobility

Toe alignment and engagement

Instead of trying to “fix” your flat feet by forcing an arch into place or relying on arch supports, train the foot to support itself.

That’s how you build resilient, functional feet that don’t break down under load.

Why Flat Feet Affect More Than Just the Feet

Weak feet lead to collapsed arches, which affect how the rest of your body moves.

This can cause:

Overpronation and ankle collapse
Knee valgus (knock-knees)
Compensations in the hips and pelvis
Increased strain on the lower back, upper spine, and even neck

Your feet are the foundation of your posture. If they aren’t working right, everything above them has to compensate.

How to Strengthen Your Arches Naturally

1. Ditch Narrow, Raised-Heel Footwear

Most shoes work against your foot’s natural mechanics. Instead, wear shoes that are:

Zero drop (no heel elevation)
Widest at the ends of the toes, not just the ball
Flexible enough to let your foot move

This helps your feet start functioning the way they were designed to.

Take a look at my Approved Shoe List that includes the footwear I approve and recommend for plantar fasciitis and other foot conditions.

2. Go Barefoot More Often

When you walk barefoot—especially on natural, uneven surfaces—you begin:

Re-engaging your arch
Re-strengthening your intrinsic foot muscles
Stimulating better proprioception and movement awareness

Even just 10–20 minutes per day of barefoot walking can make a big difference over time.

3. Use Toe Spacers

Your toes need room to spread and splay. Toe spacers encourage natural alignment of the forefoot and:

Restore proper big toe function
Increase foot stability
Reduce abnormal load on the plantar fascia

Wear them barefoot, or inside wide, natural footwear for best results.

4. Avoid Using Orthotic Support

One of the most common "solutions" offered for flat feet or plantar fasciitis is arch support or orthotics. But here’s the problem:

They don’t fix the issue. They compensate for it.

When you wear footwear with built-in arch support—or orthotics—you’re essentially outsourcing the job of your intrinsic foot muscles.

The arch doesn’t have to hold itself up, so it stops trying.

Over time, this leads to:

Weakened intrinsic foot muscles
Reduced proprioception (your foot’s ability to feel and respond to the ground)
Increased dependence on external support

Your feet become lazy.

Orthotics may provide short-term relief in acute pain situations, but long-term use only delays healing and further deconditions the structures you need to strengthen.

5. Do Targeted Arch Strengthening Exercises

You can’t expect your foot to support your body without training the muscles that support it.

Start with:

Short Foot Exercise

Engages the small muscles of the arch by “shortening” or doming the foot without scrunching or curling the toes.

Toe Splaying & Spreading

Spread your toes as far as you can and hold for 5 seconds. This builds control and coordination of toe movement.

Calf Raises (Progressive Load)

Loading the posterior tibialis, soleus, and arch musculature builds capacity and resilience.

These are all part of my plantar fasciitis rehab program—and they work by improving how your foot handles load, not by “fixing” the arch shape.

What About High Arches?

Just like flat feet, high arches can function perfectly well—or very poorly—depending on their strength and mobility.

High arches that are stiff and rigid often can’t absorb shock well, and this lack of flexibility can also contribute to foot pain, including plantar fasciitis.

Again, the solution isn’t to “flatten” the arch—but to mobilize, strengthen, and improve load tolerance.

Could A Weak Posterior Tibialis Be Causing Your Low Arches?

One of the most commonly overlooked causes of low arches—and often misdiagnosed as plantar fasciitis—is posterior tibialis dysfunction.

The posterior tibialis muscle plays a major role in:

Supporting the medial longitudinal arch (the main arch of the foot)
Controlling foot pronation during walking
Assisting with foot stabilization and push-off

When this muscle becomes weak, inflamed, or dysfunctional, it can’t support the arch properly. This often leads to a collapsed or flattened arch, especially when standing or walking—what some call acquired flat foot.

Read more about how to determine if your are dealing with plantar fasciitis or posterior tibialis tendon disorder here.

Final Thoughts from Dr. Angela

Flat feet and high arches aren’t problems in and of themselves. The real issue is a weak or dysfunctional foot that can’t do its job.

Rather than obsessing over arch shape, focus on:

Wearing shoes that allow natural function
Using toe spacers to restore alignment
Walking barefoot to re-engage muscles
Doing strength-building exercises consistently

When you build strong, mobile, adaptable feet, you protect yourself not only from plantar fasciitis—but from a host of posture and alignment issues.

If you're looking for the step-by-step approach to restoring arch strength and ending plantar fasciitis naturally, check out my free guide to resolve plantar fasciitis at home.

Dr. Angela Walk

The Plantar Fasciitis Doc