I have had advice from several people - several athletes - that I should run naturally. They say that in response to my musings about mechanics and the experimentations I have done on the treadmill. And, I'm going to have a little rant on that subject.
First, after 44 years of living in the fad-loving, infomercial that is modern culture, the odds that I would have instinctively retained a clue as to what is natural seems farfetched. Thus, the advice amounts to "run in your habitual manner". In the last 25 years, I've only run a few times to catch a door before it closes. So, I don't even have much of a habit to lean on. What I do remember is two runs - one in middle school, where I did 1.5 miles in 12 minutes with a combination of rear-foot and fore-foot; and one in high school where I did 3.0 miles on a whim (with zero preparation) and my shins just below the knees were x-ray-to-make-sure bad.
Second, evidentally experimentation is natural for me. And just as I'm experimenting physically on the treadmill, I'm exercising my brain by reading and evaluating research on running. A recent paper in the journal Nature claims that a barefoot fore-foot striker on concrete experiences less force on the musculoskeletal bits than a shod runner on concrete heel-striking in the modern, thick-soled running shoe.
There is a very loud minority out there that refer to shoes as foot coffins, insisting that shoes turn the feet - each with its 26 bones, 33 joints, 20 muscles, and hundreds of sensory receptors, tendons and ligaments - into insensate, injury-prone, flippers. This sounds at least plausible to me, so I will keep investigating. Mechanically, the arch, achilles, and calf muscles function as a spring. And a spring that has been tailored across millions of years of primate evolution. I'm inclined to trust that heritage more than a piece of rubber provided by Nike under heel. Though I must admit, my Nikes look super cool.