Re: Pain in aikido?
A lot of the differences here are based on perception. Perception of physical stimuli as pain has a lot to do with whether or not we feel in control. I've been through an impressive amount of pain.
I have removed fish hooks deeply imbedded in my fingers and not screamed - I was in control.
One of my physical therapists said "Pain comes from resistance." Read this in context please - she did not have Nikyo in mind when she said it, but my resistance to changes she was trying to effect in the postural structure of my body.
In a healthy Uke - Nage interaction the poster above wisely distinguishes between discomfort and pain. Sensitivity and communication help us avoid pain from injury and train in a healthy, compassionate way. Oh, sometimes nose bleeds happen! It's ok.