Notes
I went for a jog to Bradley Boulevard to test out my heel. After some deliberation and testing of my heel, I chose to wear the Glycerins. I've now established a spectrum between my two injuries. Heel striking, which is in part synonymous with slower running, puts a significant stress on my knees that contributes to runner's knee. The pair of shoes I trained with in the spring had a heel and forefoot design that encouraged landing on my heels and then leaving the ground with almost no push from my forefoot. What eventually got me out of that funk was wearing shoes with a lower heel and longer front, which allowed me to land less on my heel and complete my stride with a stronger push off the forefoot, which just so happens to be more conducive to brisker running. The catch is that the increased pushing off the forefoot puts more stress on the Achilles both at the end of the stride during the push and at landing when the lower heel height means a greater stretch at impact (if I land on my heel anyway).
This theory was tested quite well while running in my Glycerins. My knee trouble mostly disappeared in the last month and all tangible injury trouble leading up until now has been my heel. I figured running in the Glycerins would stress my Achilles the least. Consequently, it should stress my knee the most. This was absolutely the case, as my knee pain began almost immediately and got worse the entire duration of the run. When I finally stopped at 1.73 miles, it was 50% because of wanting to stop before the knee pain caused real inflammation and 50% because I suspected the heel should get more recovery before trying longer distances. Perhaps due to running very slow or else being distracted by monitoring my legs, my aerobic conditioning was not challenged at all and I felt I could have easily done as many miles as any healthy day.
So now I have a few options:
-Run in the Brooks Glycerin to put the least stress on my heels, but the most stress on my knees.
-Run in the Nike Free to put the least stress on my knees, but the most stress on my Achilles.
-Alternate the two to mitigate one another. (Athletes like this, but doctors hate it. Optimistically, you could argue you're strengthening your legs for both extremes. Pessimistically, you're continually exposing your legs to two competing and dangerous stresses.)
-Run in the New Balance 758 for medium heel and forefoot, which will expose and limit both injuries simultaneously.
The safe approach is probably to go any of these routes and just be extremely conservative with mileage. I have a difficult time being conservative with mileage, though.