Some of us like to hold onto our old sneakers for sentimental reasons. Perhaps they were the shoes we wore for our first marathon, or a coveted model you just can’t get anymore. Other people like to donate their old running and walking shoes to charities that provide lightly-used sneakers to those who can’t afford them.
Whichever way you celebrate the end of the life of your beloved pair of kicks, before you toss them away, donate them, or store them in some inaccessible closet, you should take a few minutes to examine the soles: The ways you’ve worn them down can actually give you some valuable insight into your gait.
“Wear patterns alert us to certain patterns of gait and tell us what position certain joints are in when you are coming into contact with the ground, as well as when you are pushing off,” explains Jacqueline Prevete, DPM, a board-certified surgical podiatrist and runner herself (with an impressive marathon personal record of 2:58).
As you walk or run, the friction and pressure between the sole of the shoe and the ground compresses and wears away some of the outsole material, shaving it down. So the wear pattern basically tells you what areas of your shoes are sustaining the most ground reaction forces when your foot comes into contact with the ground, whether you’re running, walking, or hiking.
In other words, they are almost like windows into how balanced your gait is, and can be helpful for identifying potential issues within your stride. “[You] can see whether there is any asymmetry by comparing one side to the other,” says Dr. Prevete. Which could alert you to certain patterns that could eventually lead to injury.
What can your old shoes tell you about your gait?
Wear on the inside edge of the sole
Dr. Prevete says that excessive wear on the inside, or medial, edge of a shoe means that your foot is contacting the ground in a more pronated position. Pronation is when your feet roll inward at the ankle and your arch collapses into a flattened position.
“While pronation helps the foot with shock absorption and aids in uneven surfaces, an over-pronated foot can cause problems throughout the body by passing the impact to the legs, knees, hips, and spine,” Yolanda Ragland, DPM, founder and CEO of Fix Your Feet, Inc, previously told Well+Good.
Wear on the outer edge of the sole
According to Dr. Prevete, outer edge heel wear demonstrates supination of the subtalar joint, which is the joint in the foot just below the ankle.
“Usually, outer edge wear is what’s considered expected, as normally you should be in a more supinated position during heel strike–[it’s] the ideal position for the subtalar joint to be in,” she explains. “As your foot remains in contact with the ground, you start to pronate a bit to help absorb the ground reactive force. Your foot then should switch back to a more supinated position when you are ready to propulse forward.”
Dr. Prevete says this entire cycle all happens in a matter of milliseconds, which is why detailed gait analyses are critiqued in slow motion.
Wear on the heel
Wear on the outer edge of the heel of an old sneaker is to be expected unless it’s extreme, which can indicate excessive heel striking if you’re running. Landing more on your midfoot is generally considered ideal.
Dr. Prevete says that if the wear is more centralized on the heel, it can indicate that your foot is collapsing into overpronation when you land.
Wear on one shoe more than the other
It’s also beneficial to compare the right and left shoes because our bodies aren’t necessarily symmetrical. The way you land and push off on the left foot may differ from the way you land and push off on the right foot.
Dr. Prevete says differences in the wear between your two sneakers usually indicates a biomechanical difference in the way one leg functions when compared to the other. “It can also demonstrate some muscular imbalances,” she says. These can be determined by your doctor or physical therapist–and they can help you target some weakness or deficits during your gait cycle.
So what can you do with this info?
According to Dr. Prevete, the best thing to do if you notice a prominent wear pattern on your old sneakers is to have your running or walking form analyzed. “This can be done on a treadmill, taking a video from all angles, which can be slowed down to see what position the foot is in during ground contact, midstance, and push off,” says Dr. Prevete. “Additionally, hip and knee position is also evaluated during these gait analyses to see muscular weakness above the level of the foot and ankle that can contribute to pain or symptoms while running.”
This sort of in-depth gait analysis requires a professional trained in evaluating how you run or walk, and what’s actually happening when you are putting one foot in front of the other. You can head to a physical therapist, or some specialty running stores set up with a treadmill and camera or iPad. Bring your old sneakers with you so they can take a look at your wear patterns, too.
It’s important to note, however, that running gait differs significantly from the walking gait, so if you walk and run in the same sneakers, you won’t be able to get a clear picture of biomechanical issues or gait abnormalities with either. This is just one of the many reasons most exercise professionals recommend wearing separate sneakers for running and walking.
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