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Look online for information on running shoes and you’ll soon see articles about wear patterns on the bottom of your shoes. Usually, these articles promise “secret knowledge” of what each wear pattern means and what horrible injury you’re therefore due. Individual companies often claim that certain wear patterns mean you need specific shoes or orthotics, which, lucky for you, they happen to be selling.
Most of this information is flat-out wrong. There’s simply no compelling evidence linking wear patterns on your running shoes with an increased risk for a given injury. Nor is there a relationship between your wear patterns and what kind of shoe you “should” be running in. Let’s look at what claims are most often made, why they’re almost always wrong, and what—if anything—there is to learn from the wear patterns on your shoes.
What Are Wear Patterns?
Pick up a pair of shoes you’ve run a decent amount in, and look at the outsole, which is the bottom-most part of the shoe that comes into contact with the ground. Where you see the most wear is known as the wear pattern. Most shoes have a specific outsole, usually durable rubber of some variety. Other shoes simply have a continuation of the midsole, which often wears down faster. The durability of the material used on the outsole (or lack thereof) will contribute to how much of a wear pattern you can see.
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Is There a “Normal” Wear Pattern?
There’s no universally desired wear pattern. Clinical observations have found that 75 to 90 percent of both recreational and elite runners are primarily heel strikers. These runners tend to land on the posterior lateral (rear outside) portion or posterior (rear) portion of the shoe. These runners will wear out these sections of the outsole as they continue to use their shoe.
Of the far fewer number of runners who land a little farther up—the midfoot or forefoot—many will land on the outside or center portion of those parts of the shoe. Many people land on the lateral portion of their shoes and roll inward to absorb the shock of landing. Thus, these individuals will wear out those portions of the outsole. Not everyone lands exactly like this, and variations in footstrike and form from runner to runner are normal.
As you transition through your stride and get ready to push off the ground, you can create some extra wear at the forefoot, or front of the shoe. This can be in the center, outer, or inner side, depending on how much pressure you exert through your toe-off, what available flexibility and mobility you have, and what muscles and movements you’re using to transition over your toes. There’s a great deal of variety that occurs here.
Asymmetrical Outsole Wear
There’s even variety in wear patterns between the feet of a single person. Humans are asymmetrical. The heart is off to one side, as is the liver. Just as asymmetry is present in the rest of the body, a little asymmetry in wear patterns is normal. A majority of people have a dominant side of their body, have different length feet and lower limbs, and even different spinal curves.
Evidence for Injury Risk
Here’s the main thing I want you to take away from this article: There’s no evidence that wear patterns mean anything. No studies have come out that associate certain wear patterns with certain running injuries. Looking at outsole patterns isn’t a valid or reliable method for diagnosing or assessing problems. Doing so is like trying to look through a window from a half-mile-long yard to see what’s going on inside a house. You might be able to see the window, but you really have no idea what’s happening in the house.
The only valid and reliable ways to assess someone’s injury risk or whether they have a certain pathology is to assess how they move (often by performing a camera-assisted gait analysis), test the area they’re complaining about, test their strength, test their range of motion, test their mobility, take a thorough history, ask about their training, and actually look at the person! Only then will you have an idea of what’s truly going on.
Does Running Form Play a Role?
The other problem with divining from wear patterns is that there’s so much variation among runners. Two individuals may have the exact same wear pattern but have completely different movement patterns. Another two individuals may have different wear patterns but have similar-looking running forms. So many factors contribute to your individual mechanics, such as:
- How hard you hit the ground
- What muscles you use to absorb shock and propel yourself forward
- Whether you bounce off the ground or grind into it
- How much mobility you have at your feet, knees, hips, and spine.
Only after assessing all of these elements (and more) can a qualified person make conclusions.
Other Factors That Affect Outsole Wear
More problems with basing conclusions on wear patterns include that they can be different between running shoes, they’ll change over time, and they may differ depending on what surface you run on. Different shoes have different levels of softness or firmness, different heel-toe offsets, different levels of durability, and different areas of durability. These also change as running companies continually modify their shoes.
Changing your usual running route may affect outsole wear as different surfaces, road angles, and more can influence wear. This creates even more confounding factors that make wear patterns unreliable. Seeing different wear patterns with different shoes or over time is normal.
What Your Outsole Can’t Tell You
No wear pattern has ever been linked to a pathology. Those who argue that certain wear patterns mean you pronate or supinate haven’t figured out that these terms define normal motion and, based on clinical research, have been shown to protect against many types of bone stress injuries.
Having a certain or unique wear pattern doesn’t mean you are going to have problems. Your time would be much better spent assessing your training routine, figuring out what weaknesses you might need to address, or going to someone who can help you determine the answers to one or both of those matters. Strength training and smart training plans are two of the few validated things known to reduce injury risks in runners.
What Your Outsole Can Tell You
The one thing wear patterns can tell you is when you might need to get a new pair of shoes. While certain patterns are unique to each person and don’t tell us much about the runner, wear does give us an idea about how broken down the shoe is. Each person will wear their own unique movement pattern into the shoe. The more the shoe gets worn down, the more those movement patterns will be exaggerated. Any movement faults may become more extreme as the shoe starts to break down.
Signs to Replace Your Shoes
Different shoes will break down differently. However, visual and subjective clues that you may need a new pair include:
- Creasing or wrinkling of the midsoles suggests the foam is starting to compress and will lose its shock-absorbing capabilities.
- Excessive wear on the outsole means less protection and grip. Similar to the foam compression, your unique pattern will be worn into the shoe, potentially biasing your mechanics toward one direction. This risks exaggerating any unique problems you may have and placing added stress in certain areas.
- Odd aches and pains with no other cause (overtraining, fatigue, or stress) may suggest the shock-absorbing capabilities of the shoe have decreased beyond your body’s level of tolerance.
In shoes with extremely durable outsoles, you may not be able to see this even though the foam is being broken down inside the midsole. Often, people will not understand the shoe is broken down and will get an orthotic, which really acts like a band-aid. If your shoes are worn out, get a new pair. While orthotics haven’t been shown to reduce injury risk (except in special populations), having multiple shoes in your rotation has.
The Bottom Line
Wear patterns tell you about the shoe, not the person. No wear pattern has been linked to any pathology. People move differently, and they even move differently on each side of the body. If your outsoles look extremely worn out, it’s probably time to get a new pair of shoes. It doesn’t mean you need an orthotic or need to see a medical professional. It means your shoes are worn out and you should recycle them. (There are many programs out there that recycle shoes, so please don’t just throw them in the trash.)
The remainder of your time and focus should be spent on learning how to train smarter, spending time on strength work, and investing in another pair or two of shoes. Only then will you reduce your injury risk and maybe have some peace of mind.
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Matthew Klein is a doctor of physical therapy in practice in Monrovia, California, and the founder of the Doctors of Running sport science and shoe review site.
