haha, well, RedRoan was asking for studies, so that's what I wanted to provide, along with my own experience with swimming.

Unfortunately, mine is the kind of idiopathic neuropathy that is painful. I've found basically four kinds of exercise that help me without increasing pain: swimming, stationary bicycle (one that I can use my hands on part of the time), yoga, and stretching. I can gain some fitness without increasing my pain levels with those activities. A friend who instructs in therapeutic yoga says that "triangle pose" is most helpful, and it does seem to help.

I've looked at a dozen pages just now, and I don't see any good instructions on triangle pose. I don't do as much yoga as I might, because there can be a fair amount of standing. But if pain isn't a problem, I'd really, really recommend taking yoga classes. There are various styles (and any particular teacher may be more or less helpful to you), so I'd recommend trying multiple classes. If your neuropathy shows up as numbness, the advantage is that it's a controlled environment with less opportunity for stumbling over things.

I saw a physical therapist once who remarked that stretching doesn't just stretch tendons and muscles, it also stretches nerves and that can stimulate them. Maybe that's why I find triangle pose helps--it's basically stretching both legs and arms.

I used to be a runner and I wish I could tolerate even a 1 mile run or the much longer ones I used to do. The idea of using a step machine just boggles my mind--no way! My limit is about a mile of gentle walking before I'm in more pain than I want to handle.

A doctor I saw suggested that any kind of fitness would be helpful--even if it didn't help my neuropathy in particular, it would help me feel better overall. I haven't followed that idea consistently enough yet, but it sounds true enough. Idiopathic neuropathy is so individual, and so unstudied, we each have to find what may help and what doesn't harm. Good luck.