It's been 24 hours and my calves are still kind of tight.
Under the influence of the book Born to Run, I decided to put my feet to the test: Starting from the lower trailhead in Carr Canyon, I ran Perimeter trail to Miller Creek to Clark Spring and back down Carr Road to the Jeep. Covered the 8.7 miles, 1600 feet of climbing in 2:07, about 15 minutes slower than a respectable mountain-bike time.
My Vibram Five Fingers foot gloves caught the attention of a lady on Perimeter. "You're not barefoot, are you?!" I stopped and showed off my minimalist footwear. She reached down and grabbed a couple of my toes and gave them a squeeze. "Your feet must be really tough." I laughed and said that if they were really tough, the Vibrams wouldn't be necessary. As we parted, I could see the wheels turning; she was trying to figure out who to tell about this strange trail sighting.
I put in my best licks on Perimeter, and arrived in Miller Canyon in 51 minutes. Speed-walked along the creek to the Clark Spring trailhead, where I resumed running. Parts of this passage were a little tougher--steep and somewhat loose. The Vibrams have smooth soles, with just narrow razor siping for grip. They work great on rock, but offer no mechanical assistance (e.g., lugs or tread) for coping with loose soil. Just gotta dig those toes in.
I skipped the John Cooper trail bypass and went all the way across on the Clark trail, reducing my overall mileage slightly from the mountain-bike version of the trip. By the time I got to Carr Road, I was ready to wrap it up. Those overworked calves were mooing a bit, and I was landing my strides a little slower and flatter than when I started. Amazing what a difference that makes; small chunks of gravel bit into my instep at times and I felt that I was jogging rather than running. Just before I ran out of patience, I arrived back at the Jeep.
It's the next day, and the damage assessment is in: No harm done. If I throw a trail run into the mix from time to time I'm sure I'll whip those whining calves into running bulls.