Do Insoles Fix Flat Feet?

The belief goes like this: flat feet are a fault. Your arches have collapsed, that collapse is the hidden cause of your knee, hip or back pain, and the fix is a pair of arch-support insoles that hold the foot in the shape it should have been. Many people have been told exactly this, sometimes in a shop, sometimes in a clinic, and have spent a good deal of money on it.

The evidence tells a more interesting and considerably more reassuring story. Insoles are genuinely useful for some people. But they do not fix flat feet, flat feet mostly do not need fixing, and if your feet do not hurt, this whole conversation may not apply to you at all.

First, flat feet are not a defect

A low or absent arch is an extremely common foot type. Walk down any street in Liverpool and a substantial share of the people passing you have flat feet, are entirely pain-free and have never given their arches a second thought.

Foot shape varies the way height and hand size vary. Research looking for a strong link between arch height and injury risk has repeatedly found the relationship to be weak and inconsistent. Flat feet are not a reliable predictor of who ends up in my clinic. Plenty of people with beautifully high arches develop plantar heel pain, and plenty of very flat-footed runners never do.

There is an important distinction, though, between a flexible flat foot, where an arch appears when you go up on tiptoes or when you sit with the foot unloaded, and a rigid flat foot that stays flat regardless. Flexible flat feet are usually just a normal variant. A rigid, stiff or painful flat foot, especially one that has developed relatively recently in adulthood or that only affects one side, is a different matter and deserves proper assessment.

What insoles actually do

Here is where the story has changed most over the past couple of decades. Orthoses were traditionally sold on the idea that they realign bones and correct abnormal mechanics. The current understanding is much more modest and much more useful: they alter how load is distributed across the foot and up the chain, they change the timing and magnitude of certain forces slightly, and they often make things more comfortable.

Comfort turns out to matter enormously. Evidence suggests that the insole a person finds most comfortable is frequently the one that performs best for them, which is not what you would predict if the mechanism were pure geometric correction.

So insoles are a load-management tool, not a structural repair. That reframing matters, because it changes when they are worth using.

When insoles genuinely help

There is reasonable support for foot orthoses as part of treatment for a handful of specific problems:

• Plantar heel pain, where they can reduce symptoms in the short and medium term, particularly alongside calf and foot strengthening.
• Patellofemoral pain, where they sometimes help as one component of a wider programme rather than as the treatment. My knee pain page covers that condition in more detail.
• Managing load during a flare-up, where offloading a painful area for a few weeks buys the tissue room to settle while you rebuild capacity.
• Specific foot conditions such as a painful adult acquired flatfoot, where support has a clearer role.

Notice what these have in common. In every case, the insole is treating a painful condition, not a foot shape. Nobody needs treatment for the shape of their foot alone.

Custom or off-the-shelf?

This is where the money goes, so it is worth being blunt. For most of the conditions listed above, studies comparing expensive custom-made devices with good quality prefabricated ones have generally not shown the custom versions to be clearly superior. That is not an argument that custom orthoses never have a place; for complex feet, significant deformity, diabetic foot risk or after surgery, bespoke devices prescribed by a podiatrist make real sense. But for a runner with sore heels, starting with a well-chosen off-the-shelf insole is a reasonable and much cheaper first step.

The thing that usually works better

If your feet, shins or knees hurt and you have flat feet, the more valuable intervention is nearly always strength and load management rather than support.

Your foot has a substantial amount of its own musculature, plus the calf complex and tibialis posterior running down into the arch. These structures are what actively control the foot under load. They respond to training, and unlike an insole, the effect stays with you when you take your shoes off.

Practically, that means progressive calf raises done both with the knee straight and bent, single-leg balance work, foot intrinsic exercises, and above all a sensible progression of the running or walking volume that made things sore in the first place. Sudden increases in load cause far more foot pain across Merseyside than arch height ever has.

Insoles and strengthening are not rivals. I frequently use both: the insole to make this month tolerable, the strength work to make next year unnecessary.

When to get it properly assessed

See a physiotherapist, podiatrist or your GP if you have:

• a flat foot that has developed or worsened noticeably in adulthood, particularly on one side only, or an inability to perform a single-leg heel raise
• a rigid, stiff or painful flat foot in a child or teenager
• foot pain with numbness, tingling, or any foot changes if you have diabetes, which needs prompt review
• foot pain with swelling, redness, warmth or fever
• pinpoint bone pain that worsens with impact, which may indicate a stress injury

The practical takeaway

If your flat feet do not hurt, do nothing. You do not have a problem that needs solving, and no insole is going to protect you from a future you were not heading towards anyway.

If something does hurt, get the actual diagnosis first. Then treat that condition, using insoles where the evidence supports them, and building strength and managing load in every case. Do not buy support for a foot shape; buy help for a symptom.

I assess a lot of feet across Liverpool and Merseyside, and the conversation almost always ends up being about load rather than arches. If your feet, shins or knees have been complaining, an hour spent working out why is a better investment than a shelf of insoles. You can read more about musculoskeletal physiotherapy or about physiotherapy in Liverpool.

Home visits across Liverpool and Merseyside are £90 a session, online video consultations UK-wide are £60, evenings Monday to Friday, plus Saturday and Sunday daytimes, no GP referral needed. Book at /portal/book or call me on +44 7553 370300.