One variable that is often left unmentioned when discussing what type of shoe is best for someone is how flexible or rigid the foot’s arch structure is. Because the whole reason for footwear is to better “interface” our feet with the hard flat world we’ve created, the type of materials used to execute the interface is very important, and greatly depends on the foot’s ability to work in harmony with them.
As you can see, there is significantly less surface area to bear the weight of someone’s entire body, so the amount of pressure per square inch is greater than the “normal” foot pictured above. Since it is pretty amazing that a normal foot can withstand the weight of our entire body, a pes-cavus foot type is bound to have problems commonly associated with this disproportionate weight bearing. Heel spurs, corns, and severe callusing are all very common for these type of feet.
So how do we best redistribute the weight? If we can bring the hard walking surface “up to the foot” to help bear weight on areas that are not naturally making contact with the ground, we will effectively be redistributing the weight more evenly. This is what orthotics and footwear with great footbeds accomplish. By using arch and metatarsal support to “fill in” the spaces on your foot that aren’t normally bearing weight, they help spread out the body weight your feet deal with.
Now that we understand one reason why good footbeds are important, we need to talk about the kind of materials they use, and why some are better for more rigid feet. If you can imagine taking two pieces of concrete and rubbing them together, you can start to visualize what needs to happen to interface a rigid foot with a hard walking surface. You need something soft in between! If we bring the floor up to a rigid pes cavus foot using hard materials, you will have much less chance for comfort than if those materials are soft and forgiving. Since a rigid foot can’t “wrap around” a hard walking surface to increase the area for weight bearing, you need something soft in between to “wrap around” the foot. A nice high arch made with soft compreshionable materials works perfectly to keep that rigid foot happy. The kind of footbed offered by brands like FitFlop and Vioninc with Orthaheel usually work perfectly!
|On the other side, how do we handle a flexible pronated foot where the footprint looks like this?|
As you can see by the footprint, it’s not as much a problem of increasing surface area for weight bearing as it is stabilizing the midfoot. The most common problems that people with this type of foot suffer from are ankle, knee and back pain caused by over-pronation or their feet “turning in”. So how are we going to keep these flexible feet more stable? You guessed it….more rigid materials. If we try to support a noodle with another noodle, we don’t accomplish much. The same goes for flexible feet. A nice firm footbed with great arch support like the ones found in Naot and Birkenstock (coming soon!) can be ideal!
As always, now one rule works for every foot, but for the majority of people soft insoles work best for rigid feet and vice versa.