At this time, I am attributing this minor breakthrough to a change in tactics. Due mostly to increasingly cold weather, I went out to the local Road Runner Sports store and bought a pair of more normal running shoes. After trying a few different "minimal" pairs, I opted to go with the Brooks Green Silence. Brooks has been my go-to brand for some time. They tend to fit my feet better than most other brands, being relatively long and narrow.
The Green Silence model is a very minimal shoe. It actually does not feel much heavier than my Vibrams. In addition, as the name implies, they are about as eco-friendly as you can get in a running shoe these days. They are made with recycled materials and non-toxic dyes. Even better, they have bright green soles, which I like. I always love to be just a little bit flashy when I run.
The primary reason, I believe, that running in shoes is going better than running in the Vibram Fivefingers ever has is the cushioning effect of the soles. With the surfaces I am usually forced to run on around Westminster, the 5F's leave my feet and the rest of me very exposed to pounding, which forces my calves and other supporting muscles to work much harder in order to protect the rest of my body. The cushioning in the shoes removes much of that requirement: I still run primarily on my forefoot to midfoot, but my calves, and the rest of me, does not have to work as hard.
Does this mean that my experiment with the almost-barefoot running was not a success? Not entirely. I still like the feel of running in the 5F's, but I do not think that I can build up the type of mileage I would like in them. It seems that they have definitely increased my foot, calf, and stabilizing strength, which will always be advantageous. To continue this strengthening process, I still plan to run in the 5F's two or three times a week. I plan to run my "serious" workouts in shoes from now on, and leave the 5F's for the shorter, easier runs.
As a bit of a follow-up to my own experiences with barefoot, or near barefoot, running, I will shortly be participating in a barefoot running study at CU. The goal is to study the metabolic effects of the cushioning and weight factors introduced by wearing shoes. I am very curious about what their results might be.