Ask a Foot Doctor: Running, Foot Pain, and Whether You Actually Need Orthotics

We recently hosted an AMA with Dr. Zac Cartun, physician and co-founder of Stride Soles, where we took questions about running injuries, foot mechanics, and custom orthotics.

A lot of the questions circled around the same core issue: people feel pain in their feet, knees, or hips, but they’re not sure whether the problem actually starts at the foot.

Below are some of the most common questions and answers from the session.

“How do I know if my foot pain is something serious or just overuse?”

The first thing to understand is that your foot is a mechanical structure, not just a cushion. It’s a complex system of bones, ligaments, and tendons that has to support your entire body thousands of times per day.

When people develop pain, it usually falls into one of three categories:

• Load problems – you increased activity too quickly (running, walking, standing)

• Mechanical problems – your foot is rolling or loading in a way that creates excess stress

• Footwear problems – the shoe doesn’t match the shape or motion of your foot

Pain that comes on gradually with activity—especially under the heel, ball of the foot, or along the arch—is usually a load and mechanics issue, not an acute injury.

If pain:

• worsens with activity

• improves with rest

• or appears in the same location repeatedly

that’s a strong signal that your biomechanics are contributing to the problem.

“Do orthotics actually fix the problem, or do they just mask it?”

Orthotics are often misunderstood.

They’re not meant to “immobilize” the foot or make it rigid. The goal is actually to guide how forces move through the foot while you walk or run.

Think of it less like a brace and more like re-routing pressure.

For example:

• If your arch collapses excessively, certain tendons get overloaded.

• If you supinate (roll outward), pressure shifts to the outside of the foot.

• If the forefoot takes too much load, the metatarsals absorb repeated impact.

A properly designed orthotic changes where and when those forces occur, which allows irritated tissues to recover.

In other words, it’s not just masking pain—it’s changing the mechanics that caused it.

“What’s the difference between custom orthotics and store-bought insoles?”

Over-the-counter insoles are designed for the average foot, but there’s really no such thing as an average foot.

Every person has a different combination of:

• arch height

• forefoot alignment

• heel tilt

• pressure distribution

• walking pattern

A custom orthotic starts with the geometry of your actual foot, usually captured with a scan.

From there, adjustments can be made to:

• offload painful areas

• support the arch without overcorrecting

• stabilize the heel

• redistribute pressure across the forefoot

That’s why custom orthotics often feel more subtle but more effective. They’re designed to match your foot rather than forcing your foot to match the insert.

“Can bad foot mechanics cause knee or back pain?”

Yes—and this is one of the most common things we see.

Your foot is the first contact point with the ground, so every step sends force upward through the kinetic chain:

foot → ankle → knee → hip → spine.

If the foot rolls inward excessively (pronation), the knee often rotates inward as well. Over time, that can lead to issues like:

• patellofemoral pain

• IT band irritation

• medial knee stress

Similarly, excessive outward loading (supination) can increase impact forces that travel up the leg.

Sometimes the knee or hip is where the pain shows up, but the mechanical driver is happening lower down at the foot.

“What’s the most common mistake runners make with foot health?”

The biggest mistake is assuming that pain means weakness or lack of conditioning.

In reality, a lot of injuries are mechanical mismatch problems.

Examples include:

• increasing mileage too quickly with poor shock absorption

• wearing shoes that don’t match foot shape

• ignoring asymmetric wear patterns in shoes

If you look at the bottom of your shoes and one side is worn down dramatically more than the other, that’s often a clue that your gait mechanics are uneven.

Addressing that early—through footwear, orthotics, or gait adjustments—can prevent much bigger issues later.

“If my feet don’t hurt, do I still need orthotics?”

Not necessarily.

Orthotics are most useful when someone has:

• recurring foot pain

• biomechanical asymmetry

• heavy activity loads (running, standing jobs)

• prior injuries

For some people, their natural mechanics work perfectly well.

For others, a small mechanical correction can make a huge difference in comfort, injury prevention, and long-term joint health.

The Bigger Picture: Foot Mechanics Matter More Than People Realize

The main takeaway from the AMA was simple:

Your feet set the foundation for the rest of your body’s movement.

When that foundation distributes force properly, everything above it works more efficiently.

When it doesn’t, stress accumulates in predictable places—often leading to pain in the feet, knees, or hips.

Understanding your foot mechanics isn’t just about solving foot pain. It’s about optimizing how your entire body moves.

If you’re curious about your own mechanics, Stride Soles uses 3D foot scanning and physician-guided design to create orthotics tailored to your specific movement patterns.

Because no two feet—and no two gaits—are exactly the same.