Heel Lifts and Shoe Lifts — What the Research Says, What the Experts Debate, and What One User Knows for Certain

More people than you'd expect have needed a heel lift at some point in their lives. Runners dealing with gait imbalances, people managing Achilles tendonitis, athletes correcting a short leg, patients recovering from surgery — the list is long.

And yet the heel lift, despite being one of the simplest, least expensive orthopaedic tools available, somehow sits at the center of a genuine debate in the medical community.

This page is an attempt to lay that debate out honestly — the supporting evidence, the skeptical evidence, and the personal experience of someone who has lived with leg length discrepancy for decades.

First — What a Heel Lift Actually Is

A heel lift is a firm wedge-shaped insert placed in the heel of one or both shoes. It's designed to raise the heel by a specific measured amount — usually somewhere between 3mm and 12mm — in order to correct a biomechanical imbalance.

A heel lift is not the same thing as a heel cushion or a padded insole. Cushions are designed to absorb impact and add comfort. Heel lifts are designed to change the mechanical position of the foot and leg relative to the ground. They serve completely different purposes, and the distinction matters because using the wrong one for the wrong reason produces poor results.

Where the Disagreement Lives

The core debate in the medical literature centers on leg length discrepancy — and specifically, whether a small difference in leg length actually causes the back pain, hip problems, and postural issues that many people attribute to it.

This might seem like a strange thing to argue about, but the research genuinely pulls in different directions. Some well-designed studies show a clear connection between even small leg length differences and chronic pain. Others — also well-designed — find no statistically significant link. The honest answer is that the science is not fully settled, and any clinician or website that tells you otherwise is oversimplifying.

What is clear is that for many people — not all, but many — correcting a leg length discrepancy with a heel lift produces measurable improvement in pain and function. The debate is about the population-level statistics. The individual experience often tells a different story.

What the Author Knows From 40 Years of Personal Experience

The person who invented the Clearly Adjustable heel lift — Richard Zehr — has a 3/8 inch leg length difference that he has managed for over four decades. He is an active person: a long-distance cyclist and committed walker who has had two back surgeries and a sensitive back that doesn't forgive mistakes.

His experience is direct and reproducible: without adequate heel lift compensation for his shorter leg, his gait becomes asymmetrical, his back and leg muscles accumulate stress unevenly over time, and the pain eventually becomes serious enough to require months of physical therapy to undo.

That personal experience — watching the same problem appear and resolve repeatedly in response to a single variable — is what motivated him to design a better adjustable heel lift than anything available at the time. He wears his own product in every pair of shoes he owns.

This doesn't prove that heel lifts work for everyone with leg length discrepancy. It does demonstrate that for some people, the effect is real, consistent, and significant.

What the Research Actually Says

Rather than pretending there's consensus where none exists, here's an honest look at the range of findings:

Studies That Support Heel Lift Use

Spinal motion and leg length discrepancy — A study published in the journal Spine (Kakushima, Miyamoto, Shimizu, 2003) examined how an induced leg length difference affected spinal movement during walking. The conclusion: leg length discrepancy causes the spine to compensate with asymmetrical lateral bending, and patients with this condition are at greater risk of developing degenerative spinal changes over time. The authors recommended that treatment for leg length discrepancy may help prevent those changes from progressing.

Shoe inserts and chronic back pain — A randomized controlled study published in the Archives of Physical Medicine and Rehabilitation (Defrin, Ben Benyamin, Aldubi, Pick, 2005) looked at 33 patients with chronic low back pain and leg length discrepancies of 10mm or less.

The patients who received individually fitted shoe inserts showed significant reductions in both pain intensity and functional disability.

The researchers concluded that shoe inserts are a simple, non-invasive, and inexpensive option worth adding to chronic low back pain treatment when leg length discrepancy is present.

Even small differences matter — Some research suggests that as little as 5–6mm of leg length difference can produce measurable lower body stress symptoms when the body is required to compensate for it constantly — standing, walking, and running.

The Skeptical View

Not all research arrives at the same conclusion. Some studies have found no statistically significant correlation between leg length differences below 2cm and back pain — suggesting that most people adapt to minor discrepancies without developing problems. The argument is that the human body is remarkably good at compensating, and that treating a leg length difference when it isn't causing symptoms may be unnecessary.

An older entry in Wheeless' Textbook of Orthopaedics — a standard surgical reference — suggested that discrepancies under half an inch require no treatment. The author of this page would add a pointed observation: that recommendation comes from a surgeon's perspective, where the tools available are primarily procedural. Not every measurement of a problem calls for the most aggressive solution on the shelf.

On Achilles tendon loading specifically — research from the University of Exeter (Dixon and Kerwin) found that the relationship between heel lift height and Achilles tendon force is more complex than a simple "lift reduces load" equation. Individual responses varied considerably.

The data suggest that heel lifts are not a guaranteed one-size-fits-all solution for Achilles issues, and that individual analysis matters.

This is one of several reasons why adjustable heel lifts — which allow height to be fine-tuned — are more clinically useful than fixed-height options.

The Pragmatic Middle Ground

Physical therapy and chiropractic communities have largely taken a practical view: use heel lifts when they help, monitor for side effects, and adjust accordingly. The Canadian Veterans Administration, in a technical review of leg length imbalance, concluded that it can cause osteoarthritis of the knee, hip, or back, and can cause or aggravate degenerative disc disease — supporting the case for treatment when discrepancy is present.

The American Academy of Orthopaedic Surgeons takes a measured position: minor leg length differences can often be managed effectively with a simple shoe lift, while more significant differences may require additional intervention.

The Bottom Line on the Debate

Here's a fair summary of where things stand:

• Leg length discrepancy is common — more than half of people have some measurable difference

• Whether it causes problems depends on the individual, the size of the difference, their activity level, and how their body compensates

• For people who do experience symptoms — back pain, hip misalignment, knee stress, Achilles tendon problems — heel lift correction is one of the most conservative, lowest-risk, and most reversible interventions available

• The research supporting use is solid; the skeptical research doesn't disprove the benefit, it questions the universal application

• Starting conservative and adjusting is almost always the right approach

If you are experiencing symptoms that your healthcare provider has connected to leg length discrepancy, the evidence supports giving heel lifts a careful, monitored trial. If you're asymptomatic and just curious, there's less urgency — but there's also no harm in having a measurement done.