Shoe Experiments

I have been suspecting for over a month now that my running shoes may be the reason why I have knee pain. Consider this...

• A week before I ran the Death Valley Borax Marathon on December 5th, I could barely run ten miles in my Saucony's because of knee pain. I wore different shoes (which I call "Old Faithful") during the marathon a week later and had NO knee pain. I suspected I would be walking off the course injured halfway through, but ended up feeling great the whole 26 miles.
  
• I bought a pair of New Balance 859's two weeks ago. During my first two runs in these shoes I experienced severe knee pain. A couple days after each of these two runs I wore Old Faithful and experienced NO knee pain.
  

My hypothesis here is that my Old Faithful shoes are better for my knees, while my other two pairs are hurting me. To test this, I will be doing a few experiments. Below details my first, which I conducted this weekend:

Experiment #1: Run Saturday in Old Faithful and Sunday in my NB 859's. If I only experience knee pain on Sunday, then I will settle on two theories:

1. My NB 859's are the cause of knee pain. -OR-
2. My run on Saturday fatigued my legs enough that my Sunday run would have caused knee pain if wearing either shoe.
   

Unfortunately, wearing Old Faithful on Saturday gave me a case of sore knees, so I couldn't land on either of these theories. The soreness didn't occur so much during my run, but later in the day as my legs cooled down. After this, I felt that Sunday was bound to spell disaster, which it did. At this point it may be impossible to deduce exactly what started this injury about a month ago. The point is that I'm injured and I need to get better. I have noticed that all my recent runs without knee pain have been low mileage and on dirt, so I'm going to immediately implement this training regime until I'm better. This may also mean a switch to swimming on the weekend, when I normally go on long runs. Ah, there's nothing like outdoor swimming in the dead of winter...