Went to try out a BJJ class the other day by a well known Brazilian teacher who has won many competitions. While I was there one of his senior students injured his knee while rolling and he was laying on the ground moaning in pain. Another of his students told me that over half the class had undergone knee surgery.

I'm wondering if serious injury is par for the course of training BJJ (not only knees but elbows, shoulders, necks, backs)- if there is something inseparable from training the art that eventually/inevitably leads to serious injury for the majority of practitioners? While I like the art and think its effective, I'm not keen on getting injured.