I took first aid/cpr classes from the Red cross every 2-3 years for my job. I switched jobs and took a class from an emergency responder. He said if you’re doing it right, you’re probably going to hear bones crack. I told him that in 20 years of classes, he was the first person to ever mention that. I would have honestly probably have stopped if I heard bones cracking before I took his course. That’s an important point to leave out.