The wear pattern on the bottom of your shoes can give you a glimpse into how you run. “Why do I wear on the outside border of my shoe” is likely the most common questions we get when discussing shoes with patients and clients.
The foot is designed to be mobile and adaptive. We have a rear, mid, and forefoot that work like differential on a truck, allowing each third to twist in opposite directions. That’s pretty important, right? If you’re running trails or even walking across the yard and you step onto an uneven surface you would benefit from your foot adapting to that change in surface.
Let’s say we’re not running on uneven surfaces, but more of a concrete jungle scenario. From the point of initial contact to push off, our foot goes through specific changes based on the needs of the motion. Now there are issues that arise where too much or too little mobility/strength can effect these circumstances, but let’s go with the norm.
When our foot enters the ground, it should, I repeat, should, turn in. Turning in of the foot and ankle is known as ‘supination’. Think of this as locking the foot into place for impact. You’re about to land with 3-5x your body weight, you would ideally like the 26 bones of your foot and ankle to be stable, preventing excessive movement. This impact and turning in of the foot and ankle is why the outside portion of our shoe wears.
From initial contact to mid stance, our foot ‘unlocks’ and pronates to the ground. The foot transitions from supination to pronation to distribute the forces of impact. This generally does not shoe wear on the bottom of your shoe unless you have poor control. The transition from initial contact to mid stance is controlled by key muscle groups. If these muscle groups are weak, it allows for excessive pronation and overstretching of specific tendons and notably, your plantar fascia.
Those same muscles that lowered your foot down now fire in reverse, or concentrically. The muscles pull up on the arch, knee, and hip to get your foot back to a rigid, supinated, position. Again, this is ideal. During push off off we use our foot as lever to produce force. You may see some wear patterns from push off. Ideally, push off occurs through the 2nd and 3rd toes.
It’s worth noting that you shouldn’t have to force these motions. Don’t think to yourself, “Ok, land on out outside of my foot, allow it to pronate, and the pull back to the first and second toe.” Your body knows how to operate and what’s best. Instead, work on balance and strength. Most feet start in the right position, but lack the strength and balance to appropriately progress through the other stages. Week feet allow for the foot to overpronate, over stretching tissue and preventing a solid pushoff through the second and third toes.