--it's always a possibility that multiple things are happening--some people report increased symptoms, especially parastheses, with exercise, but whether this is from disturbing damaged nerves or from nerves actually waking up from increased circulation and their receiving more oxygen/nutrients may be difficult to determine.

We've got a thread going that talks about healing nerves causing increased symptoms (in the context of laser light therapy or LED therapy), at least for a time:

http://neurotalk.psychcentral.com/thread168681-3.html

My bias tends to be that one should exercise to tolerance--exercise certainly has benefits beyond possible increased circulation to nerves. But I realize this tolerance varies widely.