I don't think this is arm pump. When I'm doing better than normal, for me, sometimes my right hand will get that tingling, loss of feeling thing going on. I try to do the things recommended here for arm pump, water, relax, exercises, etc. I'm pretty sure it's from hanging on too tight, 'cuz I'm scared. I was wondering if changing the grips might help - something tells me if they were fatter they would be better. Any thoughts?