This was the second time I've had it so it wasn't as bad, because I knew what to suspect and that it wasn't going to kill me. But yecch.
Fortunately, it seems that the nerve conductivity in both of my arms is fine. And to be fair, the only time anyone HAS an EMG is when there's something sufficiently nasty going on that you're willing to have 45 minutes of discomfort.
The interesting part was listening to my muscle electricity as noise, rather like the static on a short wave radio. When I strained against pressure as instructed, I made VERY LOUD static.