It has been a while, so I don't remember the exact details. In both cases, the symptoms were pain and paraesthesia in my hands and lower arm, although the locations might have been somewhat different. In one, the issue was that I was holding my head and neck forward, sort of cantilevered out. This caused muscle inflammation in the back of my neck, irritating a nearby nerve. In the other, it had to do with holding my shoulders forward, causing a nerve impingement on my chest. In both cases, it was part of an overall hunched-forward posture, so... you know, "don't do that". :-) I don't remember the specific exercises, but I think they had something to do with strengthening opposing muscles.