Here is my latest update.
The primary cause is in my foot. Abnormal foot strike=abnormal leg function. Sounds like a prime example of, "usually the simplest answer is the right one." I have developed a cascade of problems (ie: mild peroneal nerve disfunction, hip malalignment, leg muscle disfunctions) because of what is going on in my left foot. My "dead leg" is more of a "heavy leg" that because of the inability to properly bear weight through the foot, I have developed an abnormal adaptive foot strike which has further affected the kinetic chain of muscles up my leg and in the hip.
So it is narrowed down to the left foot, but now I am in the process of trying to figure out what specifically is going on in there. As far as symptoms:
1. Incredible left foot stiffness compared to the right foot, both walking and running. Sometimes on really bad days, my left foot feels rigid and bricklike. Comparably, I feel ZERO symptoms of anything in my right foot EVER.
2. When walking, my left foot turns in so that my big toe is not pointing straight ahead but is pointing to the right. Picturing a clock face, if the big toe were pointing straight ahead and that was 12 o'clock, my big toe is pointing at 2 o'clock. If I try to consciously correct this and force my big toe to hit the ground straight ahead at 12 o'clock, I feel pain right on top of the foot where the ankle bends, but a hair more medially than laterally. So, I imagine to avoid this, my body has developed the adaptive behavior of turning the foot to avoid putting weight through the ankle there where it causes pain.
3. If I am standing on two feet and relax so that I am weightbearing evenly on both feet, I feel tightness in my left midfoot. Specifically, closer to the ankle than the toes, and closer to medial than lateral. It feels like something is caught, or gets caught in there.
4. If I am standing on just my left foot and lift my heel off the ground so that I am fully weightbearing on the ball of the foot, I get a sharp pinching/shooting pain through my midfoot. Sometimes I feel the shoot of pain when I release the weight from my foot.
5. Because of #3 and #4, I can see how my body has adaptively learned to avoid bearing weight on the left side--- my left foot strike is very passive with longer ground contact time than the right. On my right leg stride, I have a quicker toe off than the left. On my left leg stride, I sort of "roll up" to a toe off so that my ground contact time is longer. That is IF I'm able to get up on my toes on a good day. Often times my left foot/ankle feels inable or somehow physically inhibited to do this and bear weight--- the result being I am completely flat footed on the left and weight is through back of foot nearer heels. If I consciously/awkwardly force myself to get up on my toes more, I get the sharp pinching/shooting pain (the same one I explained about that I can simulate by simply standing on one foot with the heel off the ground) and my foot buckles/gives in as though I've stepped in a divot.
6. My left leg is a whip leg (left heel doesn't stay directly behind left butt cheek but flares outside a bit). If my foot is pointed to 2 o'clock, I guess my heel would come around at 7 o'clock (butt cheek being 6 o'clock)? It takes longer for me to bring my left leg around through a stride cycle than the right. This is probably because that "slow" foot strike and longer ground contact time on the left slow the momentum of the leg... ???
7. Just standing on two legs shoulder width apart, I pronate. BUT, when running, my right foot is very neutral and my left foot actually supinates with inversion. Meaning, as in my description above of the big toe pointed at 2 o'clock when WALKING, when RUNNING, picture that same foot placement, but with the foot tipped laterally so that I'm almost running on my 4th toe and pinky toe some bad days. This is highly visible in the different wear pattern of my right and left shoes.
8. My symptoms have changed through the years. My left foot used to get a bit of a foot slap/floppy foot but now is pretty much beyond that. It's either evolved into a stiff foot, or, again, I've developed some sort of adaptive behavior to avoid/correct for this. As a testament to the changing foot symptoms, I posted about this same thing in 2004:
http://www.letsrun.com/forum/flat_read.php?thread=651955
Does anyone have any similar symptoms? Thanks to everyone. We've just got to keep working and we will figure it out!!!