In reply to Pay Attention:
On the brake hand?
Possibly belaying palm up, with rope held above the belay plate, then on fall hand dropped and twisted into lock off position, causing the rope to be over the forearm.
On live hand?
Possibly as fall occurs, live hand above the live rope and dropped over the top of it to grab the dead side to help the brake hand.
I can think of several other scenarios where a rope burn could be obtained on the forearm near the elbow, but these are the two most common positions that I see/ where it could have/has happened!
It suggests to me that some attention be paid to belaying technique.
P.s I also learned to climb on hemp with body belay and friends managed some nasty burn from my enthusiastic leading. I always wore thick sleeves!
Post edited at 09:55