I'm no expert, but if it were me here's what I'd do.

Sounds like maybe a biomechanical problem - possibly pinching a blood vessel somewhere in the left leg (do you get any cramping in the leg?).

I'd try to be conscious of my running form - maybe have someone watch me. Check for uneven wear on the soles.

Are you less flexible with your left leg?

I didn't even think about checking my shoes.

When this starts happening, all I can do is think about my form. I know it's breaking down, but my brain doesn't seem to be able to make my leg do what I want.

I am a little less flexible (and less strong probably, since I'm right-side-dominant) in my left leg.

I just don't have much confidence in doctors for find this. I've been to them with problems in the past, and they haven't done much. Things have always sorted themselves out, but maybe I need to see someone about this.

I just wanted to make sure this wasn't something common. It's really bizzare.

Thanks for your input.

I hear you about going to a doctor. They're really not trained in biomechanics or sports physiology. When I do bring myself to go to one, its usually just to get the ok to go to a physical therapist. That's changing as many PTs are going PhD and state legislature is coming into place so that you don't need a prescription from your doctor.

Not saying that a doctor won't be helpful. They may help determine very well if it is a vessel occlusion. But the person to see (in my opinion) is a PT. Unfortunately I've found that PTs range from worthless to fantastic. If you do go the route of PT, ask athletes in your area who they'd reccommend. Some PTs never see sports related stuff at all and deal only with things like rehab from accident and such - some specialize in athletes. Look for one that will do a zillion and one tests on you (arthropometric measures, flexibility tests, strength tests, watching you run, etc.) in order to find the CAUSE of the problem.

Best of luck

Twist - I'm no doctor but I have had a somewhat similar problem for the past 4 years (left leg pain/numbness radiating from ankle up to butt, usually after a run). I went thru 2 MRI's, ankle specialist, back specialist, PT, ... with no help, very frustrating. Finally a couple months ago I went to another PT who finally figured it out. There were several things going on: 1) My right leg was weaker which made my left leg work harder ( I had always assumed that it was the other way around). 2) I have a nerve which was getting pinched off as it ran thru the glut max. muscle 3) I had under developed muscles around the glut max. (i.e. glut med.) which caused the glut max. to have to work too hard, which in turn caused the pinching. These problems led to other areas trying to compensate (i.e hips) which caused their own problems. Solution came with paying increased attention to running form and balance, (goofy looking) exercises to work specific underdeveloped muscles (glut med.), and gradually increasing volume. Once I got it figured out, I went back to 2 miles on a treadmill and worked back up from there. It really didn't take that long once you break the inflammation cycle. Otherwise you will be where I have been: run, run run, off for three weeks, run, run, off again... Bottom line: Don't give up and try to get to the best PT in your area. JKW.

Thanks a ton!

My fiancee used to work for a PT. I'll see if she knows a really good one.