As I detailed in this post, I had a bout with Runner's Knee (patellofemoral syndrome, to address it formally) a couple of years ago. I attributed it in part to the shoes I was wearing at the time. What I've since come to realize is that those overly-cushioned shoes merely exaggerated poor form.
Well, RK is back. This time, however, I've been doing most of my miles in minimalist shoes like the Vibram FiveFingers Speeds, or barefoot. I've had many successful miles in the Speeds, in the VivoBarefoot Ultra, and barefoot this summer. I've increased my mileage, as I did the last time RK appeared, and this time I think it's safe to say that while the shoes, even minimalist shoes, accentuate the conditions that lead to RK, they're not the cause. RK re-appeared on a 10k run in the Speeds, by the way.
When RK first appeared switching to Vibrams from the NB MT100s was enough to make it go away. That's clearly not going to work this time. So what could it be?
It's got to be form. Today I went for a 10 mile Maffetone run, 5 on road, and 5 on trail. I wore the Speeds, as it was in the low 30s F at the beginning of the run. RK appeared almost immediately on the road stretch, but went away when I got on the rougher trail sections, only to reappear on the flat parts of the trail.
As I've posted before, I've been working on form issues on my weaker right leg. While that leg is not 100%, it's much improved, and running on the trails I ran today is where those issues first appeared. The right leg was good to go today. One of the key suggestions Lee Saxby gave me was to press down on the big toe while running. This resolved the metatarsal-cuboid joint pain I was having almost immediately.
So once I got back to the road section (after stubbing my second toe on my right foot nicely on the trail: blood from the nail, but no break: thank Heavens for shoes sometimes...), I took off my shoes for the 2.7 mile run home. RK continued to bother me, even barefoot. So finally what I decided to do, as an experiment, was to exaggerate the toe-press. Basically, I was running on my big toes. This forced my left foot inward. My right big toe and foot have straightened much more than my left, and I have much more trouble flexing the left big toe down, so this seemed like a pretty good approach to take. My hypothesis is that the feet should be doing pretty much the same thing, so if one leg hurts and is working differently from the other, try to make it the same.
Running on the big toes was kind of an odd feeling, and a bit of a strain on the calves, including a nasty pull in my left calf I suffered a few weeks ago while mountain biking. I probably ran about 1.2 miles on my big toes, until I got home.
RK is completely gone in the left knee. It feels great.
Your mileage may vary. :)
P.S. I forgot to mention one of the key hints: I've been getting pain in the tendon under the second toe on the left foot during runs. Lee had said that people often put too much pressure down on the second toe, which is why pressing down on the big toe makes a difference. You're shifting the pressure to where it ought to be.