Flat feet and running aren't automatically a bad combination — plenty of runners with low or collapsed arches log kilometres injury-free for years. The problem shows up when a flatter arch changes how load travels through the foot and up the leg faster than the body adapts to it, and mileage is exactly the kind of repetitive stress that exposes that mismatch. For some runners that's a non-issue. For others, it's the reason arch pain, shin splints, or knee soreness keep returning every time training volume climbs.

As Chiropodists at Donwood Foot and Orthotic Clinic in North York, we see this pattern often in runners training for Toronto's spring and fall race calendar: pain that wasn't there at low mileage, that appears consistently once weekly distance crosses a certain threshold. Here's how to tell whether flat feet are actually the driver, and what helps when they are.

Key Takeaways

• Flat feet only become a running problem when they change how load moves through the foot faster than the body can adapt — many flat-footed runners have no issues at all

• Arch pain, shin splints, one-sided knee soreness, and a foot that visibly rolls inward late in a run are the clearest signals worth checking

• A gait assessment is how a Chiropodist tells the difference between a flat-foot-related pattern and an unrelated running injury

• Custom orthotics are built to a runner's specific foot and gait pattern — a different starting point than an off-the-shelf insole

• Shoe choice and orthotic fit work together; neither replaces the other

Why Flat Feet Behave Differently Under Running Load

Standing and walking put far less repetitive stress through the foot than running does. A flatter arch tends to let the foot roll inward (pronate) more than a higher arch, and some inward roll is normal and even shock-absorbing. Running problems tend to appear when that roll is excessive or poorly controlled, because it changes the angle at which force travels up through the shin, knee, and hip with every one of the thousands of strides in a typical training week. The foot itself isn't necessarily "wrong" — it's that the pattern doesn't hold up as well once mileage increases.

Symptoms That Point to a Flat-Foot-Related Running Injury

• Arch or heel pain that builds during a run and eases with rest, rather than pain that's there from the first step

• Shin splints (aching along the inner shin) that appear as weekly mileage increases

• Knee pain on one side, often the inside of the knee, without a specific twisting injury to explain it

• Visible inward rolling of the ankle in the later stages of a run, when supporting muscles are fatigued

• Uneven shoe wear, especially heavy wear on the inner edge of the sole

None of these symptoms are unique to flat feet on their own — that's exactly why an assessment, not a guess based on arch height, is the useful next step.

How a Chiropodist Assesses a Runner's Feet

A proper assessment looks at more than whether the arch is low. It typically includes watching how you walk and, where relevant, run, checking joint flexibility and muscle strength through the foot and ankle, and reviewing your training history and current running shoes. This is the same process behind a gait analysis — it's what separates "flat feet are probably fine for you" from "this specific pattern needs support."

Custom Orthotics vs Off-the-Shelf Running Insoles

Custom orthotics are built from a mould or scan of your own feet and adjusted for your specific gait pattern, rather than shaped to an average foot. That's the main practical difference from a store-bought insole: a generic insole can add cushioning or a general arch bump, but it isn't built to control the specific way your foot moves through a stride. For runners whose symptoms track closely with a flat-foot pattern, that distinction is usually where the benefit comes from.

Choosing Running Shoes When You Have Flat Feet

Orthotics and shoes work as a pair, not as substitutes for each other. A shoe with a stable, structured heel counter generally pairs better with a corrective orthotic than a very soft, minimal shoe, since the orthotic needs a stable platform to do its job inside. If you already use custom orthotics, bring your current running shoes to any assessment — fit inside your actual training shoe matters as much as the device itself.

When It's Time to See a Chiropodist

Occasional post-run soreness that fades within a day or two is a normal training response. A symptom that repeats at the same point in every long run, that's getting worse rather than settling with rest, or that changes how you run to avoid it, is worth a proper assessment rather than pushing through on hope. Extended benefits are accepted, with direct billing available for most major insurance providers.

If arch pain, shin splints, or one-sided knee soreness keep showing up as your training builds, book a foot assessment online or call (416) 445-1414 — we're at 51 Underhill Dr. in North York.

Frequently Asked Questions

Do all runners with flat feet need orthotics?

No. Many runners with flat feet train injury-free without any device. Orthotics are useful when a flat-foot pattern is linked to a specific, recurring symptom — they aren't a routine requirement just because an arch is low.

Can I tell if my flat feet are causing my running injury without an assessment?

Not reliably. Arch pain, shin splints, and knee pain can come from training load, footwear, or an unrelated biomechanical issue as easily as from a flat-foot pattern. A gait assessment is how a Chiropodist distinguishes between these causes rather than guessing from arch height alone.

How long does it take custom orthotics to help with a running-related symptom?

Many runners notice a difference within a few weeks of consistent wear, though full adaptation to a new orthotic can take longer, especially if training volume is also being adjusted. Orthotics work alongside training changes, not instead of them, in most cases.