Jan - I'm just guessing, but for me, it seems that the treadmill is problematic because it forces me to walk and jog in a straight line, rather than weave. I am trying to relearn to ambulate with my legs closer together, as suggested by the therapist. I have probably been walking the way I do for sometime, (legs apart, somewhat flat footed stomping) while my brain learned (incorrectly) to compensate for the damage caused by the AN nerve involvement. I wasn't even aware of all of this until I went to therapy - but I stand with my legs wide apart in order not to lose my balance, which also throws my back out of alignment and screws up my posture. This commonly happens to people who are older to me. I am attempting to correct these problems.
Anyway, as I said, I can't weave all over the place while on the treadmill, and this oddly results in a bit of dizziness as my little brain is overworked trying to relearn the correct way to walk or jog. This is the best I can do to explain this, as I understand it. I had noticed for the past couple years that my footprints in snow were weaving about quite a bit - now I understand why!