Tag Archives: supination

Don’t run above your pay grade: the (not so) hidden dangers of maximalist shoes.

There is a segment of the running community that continues to insist that maximalist shoes are the way to go, and that minimalism is nothing but a “fad.” This insistence goes against every biomechanical and physical principle that I can think of. One of the ways in which maximalist shoes violate these mechanical principles is by having wide soles. This is incremental: the more maximalist, the greater the violation.

When running in maximalist shoes, the impact forces incurred during the landing phase are much greater. Take for example the following picture, which shows the back of a shod and an unshod foot. When the foot is fully pronated at the point of ground contact, the sole forms an acute angle with the ground. The vertex of the angle is the outside of the foot; the point of contact. When the runner is unshod, the sides of this angle aren’t very long. I represent this as the innermost arc (from the vertex). However, when the runner is shod, the sides of the angle are much longer; this is the outermost arc.

shoe vs. foot

Because the arc is much longer when the foot is shod, the inside of the foot will accelerate over a comparatively longer distance (the length of the bigger arc) in order to lay flat on the ground. This means that the overall forces that travel up through the foot and into the leg are that much greater when running in big-soled shoes.

There are two important points here: first, the modern running shoe was designed to artificially extend the stride. As the stride extends, the impact forces are greater and greater. This isn’t a problem when the runner’s muscles have developed to extend the stride; most likely they have also developed to absorb and dissipate those increased impact forces. But when the stride is lengthened artificially, the runner hasn’t “earned” the right to interact with those forces—and they’ll get injured.

Similarly, the shod foot in particular has no business having a wider sole. By definition, a habitually shod foot is weaker than a habitually unshod foot. And because the forces created upon landing/supination are much greater when shod than when unshod, the possibility of injury skyrockets: the weakened structure is generating with forces much greater than those which the stronger structure would ever generate.

That’s a bit of a problem.

But there is a second point to be made here: this analysis is based on simple physics and geometry. And yet, the multibillion-dollar running shoe industry pays very little heed to the physical, biological, and mechanical principles by which the body moves, and by which it grows and develops.

Out on the road, halfway into the marathon, the maximalist/minimalist debate doesn’t matter. Out there, you aren’t debating the minimalists. You’re debating physics. You’re debating biology. You’re debating geometry. If the worldview that you approach that debate with doesn’t heed the relevant laws and principles, you’re going to lose. In direct measure to how badly you lose this debate, will be the magnitude of your injuries.