...and the lack there of.
Here's a link to a video that at :34 shows two clips of a foot landing (it seems like running.) They are both shown from the lateral aspect of the foot.
Watch how the first one lands, absorbs beautifully, smoothly, with a fully flat foot.
Watch how the second, lands, shudders, always with an arched foot that never absorbs.
This is a great visual of what's often said, but hard to see. When the foot is too weak, immobile, unstable or (some studies are saying) too cushioned, to provide the shock absorbtion, vertical impact loading is greater.
I'm sensitive to the lateral aspect of the foot as Eli Thompson, a structural integrationist (and more) pointed out that mine were high. It made me think, but why? I haven't hardly worn shoes lately and my feet are otherwise only getting bigger and better.
And then I realized. I haven't been wearing shoes EXCEPT my cycling shoes. One look at them and it was clear they were the current culprits. At the time I was commuting to and from work over two steeply graded climbs. EVERYDAY. And I otherwise like to ride my bike, a lot. I was aware of their tapered toe box but I had never thought further than that.
Here they are. Note the TOE SPRING too...
Alas...the oddities of the shapes of shoes continues...