I'm a runner and after about 3 miles on fairly level surfaces, my big toe wants to rise up off the bed of my shoe. If I continue to run, my leg sort of "gels" up and then pretty soon I get the sensation that I'm running on the outside bottom of my foot. If I stop and stand still or do a short, simple stretch I can then run again for another quarter mile or more with no problem. The problem doesn't occur if I'm running up or down steeper hills on trails.
Anyone ever hear of this condition before or have any hints as to what might be causing it?